0000950170-24-017879 | 10-K | XBRL Viewer | Ultragenyx Pharmaceutical INC

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License and Research Agreements - Solid Biosciences, Inc. - Additional Information (Details) $ in Thousands	1 Months Ended		12 Months Ended
	Oct. 31, 2022 shares	Oct. 31, 2020 USD ($) shares	Dec. 31, 2020 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Common stock investment value				$ 82	$ 70
Solid Biosciences, Inc.
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Remaining consideration paid			$ 13,200
Business acquisition, consideration transferred			$ 40,000
Common stock investment value		$ 26,800
Description of the stock split	In October 2022, Solid announced a 1 for 15 reverse stock split. After the split, the Company held 521,719 shares of Solid's common stock.
stock split conversion ratio	1
Number of common shares held after split \| shares	521,719
Collaboration Agreement \| Solid Biosciences, Inc.
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of common stock purchased \| shares		7,825,797
Aggregate purchase price		$ 40,000
Maximum \| Collaboration and License Agreement \| Solid Biosciences, Inc.
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Development milestone payments		25,000
Regulatory milestone payments		65,000
Commercial milestone payments		$ 165,000

Income Taxes - Schedule of Tax Effect of Temporary Differences to Significant Portions of Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Loss carryforwards	$ 266,253	$ 231,835
Tax credits	305,198	260,546
Stock options	44,795	39,784
Accruals and reserves	27,694	27,029
Fixed assets and intangibles	33,853	39,233
Liabilities for sales of future royalties	205,400	214,900
Basis difference in equity investments	8,423	8,971
Capitalized research and development costs	149,898	75,335
Other	281	3,028
Gross deferred tax assets	1,041,795	900,661
Valuation allowance	(1,035,836)	(894,518)
Total deferred tax assets	5,959	6,143
Deferred tax liabilities:
Gross deferred tax liabilities	(36,017)	(37,810)
Net deferred tax liabilities	(30,058)	(31,667)
Right-of-use Lease Assets
Deferred tax liabilities:
Gross deferred tax liabilities	(5,329)	(6,143)
In-process Research and Development [Member]
Deferred tax liabilities:
Gross deferred tax liabilities	$ (30,688)	$ (31,667)

Intangible Assets, Net - Additional Information (Details) 1 - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
IPR&D Assets
Indefinite-Lived Intangible Assets [Line Items]
Business combination recognized intangible assets	$ 129.0	$ 129.0

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Basis of Consolidation

The Consolidated Financial Statements include the accounts of Ultragenyx Pharmaceutical Inc. and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated.

Use of Estimates

The accompanying Consolidated Financial Statements have been prepared in accordance with U.S. generally accepted accounting principles, or GAAP. The preparation of the Consolidated Financial Statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent liabilities and the reported amounts of expenses in the Consolidated Financial Statements and the accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to clinical trial accruals, fair value of assets and liabilities, income taxes, stock-based compensation, revenue recognition, and the liabilities for sales of future royalties. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Actual results could differ from those estimates.

Cash, Cash Equivalents, and Restricted Cash

The Company considers all highly liquid investments with original maturities of three months or less from the date of purchase to be cash equivalents. Cash equivalents consist primarily of amounts invested in money market accounts.

Restricted cash primarily consists of money market accounts used as collateral for the Company’s obligations under its facility leases and the gene therapy building construction project.

The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the Consolidated Balance Sheets that sum to the total of the same such amounts shown in the Consolidated Statements of Cash Flows (in thousands):


	December 31,
	2023		2022		2021
Cash and cash equivalents	$	213,584	$	132,944	$	307,584
Restricted cash included in other current assets		2,008		862		—
Restricted cash included in other non-current assets		3,807		3,795		2,001
Total cash, cash equivalents, and restricted cash shown in the statements of cash flows	$	219,399	$	137,601	$	309,585

Marketable Debt Securities

All marketable debt securities have been classified as “available-for-sale” and are carried at estimated fair value as determined based upon quoted market prices or pricing models for similar securities. Management determines the appropriate classification of its investments at the time of purchase and reevaluates such designation as of each balance sheet date. Investments with a maturity of one year or less from the balance sheet date are reported as current marketable debt securities and investments with a maturity of greater than one year from the balance sheet date are reported as non-current marketable debt securities. Unrealized gains and losses are excluded from earnings and are reported as a component of comprehensive loss. Realized gains and losses and declines in fair value judged to be other than temporary, if any, on available-for-sale securities are included in other income (expense). The cost of securities sold is based on the specific-identification method. Interest on investments is included in interest income.

Equity Investments

The Company records investments in equity securities, other than equity method investments, at fair market value, if the fair value is readily determinable. Equity securities with no readily determinable fair values are recorded using the measurement alternative of cost adjusted for observable price changes in orderly transactions for identical or similar investments of the same issuer less impairment, if any. Investments in equity securities are recorded in Equity investments on the Company's Consolidated Balance Sheets. Unrealized gains and losses are reported in Change in fair value of equity investments on the Company’s Consolidated Statements of Operations. The Company regularly reviews its non-marketable equity securities for indicators of impairment.

Concentration of Credit Risk, Credit Losses, and Other Risks and Uncertainties

Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash, cash equivalents, and investments. The Company’s cash, cash equivalents, and investments are held by financial institutions that management believes are of high credit quality. The Company’s investment policy limits investments to fixed income securities denominated and payable in U.S. dollars such as U.S. government obligations, money market instruments and funds, corporate bonds, commercial paper, and asset-backed securities and places restrictions on maturities and concentrations by type and issuer. Such deposits may, at times, exceed federally insured limits. The Company has not experienced any losses on its deposits of cash and cash equivalents and its accounts are monitored by management to mitigate risk. The Company is exposed to credit risk in the event of default by the financial institutions holding its cash and cash equivalents, corporate issuers, and other financial instruments, to the extent recorded in the Consolidated Balance Sheets.

The Company is exposed to credit losses primarily through receivables from customers and collaborators and through its available-for-sale debt securities. For trade receivables and other instruments, the Company uses a forward-looking expected loss model that generally results in the earlier recognition of allowances for losses. For available-for-sale debt securities with unrealized losses, the losses are recognized as allowances rather than as reductions in the amortized cost of the securities.

The Company’s expected loss allowance methodology for the receivables is developed using historical collection experience, current and future economic market conditions, a review of the current aging status and financial condition of the entities. Specific allowance amounts are established to record the appropriate allowance for customers that have a higher probability of default. Balances are written off when determined to be uncollectible. The Company’s expected loss allowance methodology for the debt securities is developed by reviewing the extent of the unrealized loss, the size, term, geographical location, and industry of the issuer, the issuers’ credit ratings and any changes in those ratings, as well as reviewing current and future economic market conditions and the issuers’ current status and financial condition. There was no allowance for losses on available-for-sale debt securities which were attributable to credit risk for the years ended December 31, 2023 and 2022.

The Company is dependent on third-party manufacturers to supply products for research and development activities in its programs. In particular, the Company relies and expects to continue to rely on a small number of manufacturers to supply it with its requirements for the active pharmaceutical ingredients and formulated drugs related to these programs. These programs could be adversely affected by a significant interruption in the supply of active pharmaceutical ingredients and formulated drugs.

Inventory

The Company values inventory at the lower of cost and net realizable value and determines the cost of inventory using the average-cost method. The Company expenses costs associated with the manufacture of product candidates prior to regulatory approval. Inventories consist of currently approved products. The Company periodically reviews its inventories for excess amounts or obsolescence and writes down obsolete or otherwise unmarketable inventory to its estimated net realizable value. Management determines excess inventory based on expected future demand. Estimates related to future demand are sensitive to significant inputs and assumptions such as acceptance by patients and physicians and the availability of formulary coverage and adequate reimbursement from private third-party payers for the product.

Property, Plant, and Equipment

Property, plant, and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation and amortization is computed using the straight-line method over the estimated useful lives of the respective assets. Depreciation and amortization begins when the asset is placed in service. Interest costs incurred during the construction of major capital projects are capitalized until the underlying asset is ready to be placed in service. Maintenance and repairs are charged to operations as incurred. Upon sale or retirement of assets, the cost and related accumulated depreciation or amortization are removed from the balance sheet and the resulting gain or loss, if any, is reflected in operations. See “Note 4. Balance Sheet Components” for further disclosure on the useful lives of property, plant, and equipment.

Intangible Assets

Finite-lived intangibles consist of contractual payments made for certain milestones achieved with collaboration partners. The contractual payments are recorded as intangible assets and are amortized over their estimated useful lives. The Company reviews its definite-lived intangible assets when events or circumstances may indicate that the carrying value of these assets is not recoverable and exceeds their fair value. The Company measures fair value based on the estimated future undiscounted cash flows associated with these assets in addition to other assumptions and projections that the Company deems to be reasonable and supportable.

Indefinite-lived intangibles consist of acquired in-process research and development, or IPR&D. IPR&D assets represent capitalized incomplete research projects that the Company acquired through business combinations. Such assets are initially measured at their acquisition date fair values and are tested for impairment annually and whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. When development of the project is complete, which generally occurs when regulatory approval to market a product is obtained, the associated assets will be deemed finite-lived and will be amortized over a period that best reflects the economic benefits provided by these assets.

If it is determined that an intangible asset becomes impaired, the carrying value is written down to its fair value with the related impairment charge recognized in Consolidated Statements of Operations in the period in which the impairment occurs. The Company has not recorded any impairments of intangible assets to date.

Goodwill

Goodwill represents the excess of purchase price over fair value of net assets acquired in a business combination and is not amortized. Goodwill is subject to impairment testing at least annually during the fourth quarter or when a triggering event occurs that could indicate a potential impairment. If it is determined that the goodwill becomes impaired, the carrying value is written down to its fair value with the related impairment charge recognized in Consolidated Statements of Operations in the period in which the impairment occurs. The Company has not recorded any impairments of goodwill.

Impairment of Long-Lived Assets

The Company evaluates its long-lived assets, including property and equipment, for impairment whenever events or changes in circumstances indicate that the carrying value of these assets may not be recoverable. Recoverability of these assets is measured by comparison of the carrying amount of each asset to the future undiscounted cash flows expected to result from the use of the asset and its eventual disposition. If the asset is considered to be impaired, the amount of any impairment is measured as the difference between the carrying value and the fair value of the impaired asset. The Company has not recorded material impairment of any long-lived assets.

Accruals of Research and Development Costs

The Company records accruals for estimated costs of research, preclinical and clinical studies and manufacturing development. These costs are a significant component of the Company’s research and development expenses. A substantial portion of the Company’s ongoing research and development activities are conducted by third-party service providers, including contract research organizations. The Company accrues the costs incurred under its agreements with these third parties based on actual work completed in accordance with agreements established with these third parties. The Company determines the actual costs through obtaining information from external service providers as to the progress or stage of completion of the services and the agreed-upon fee to be paid for such services.

Revenue Recognition

Product Sales

The Company sells its approved products through a limited number of distributors. Under ASC 606, revenue from product sales is recognized at the point in time when control is transferred to these distributors. The Company also recognizes revenue from sales of certain products on a “named patient” basis, which are allowed in certain countries prior to the commercial approval of the product. Prior to recognizing revenue, the Company makes estimates of the transaction price, including any variable consideration that is subject to a constraint. Amounts of variable consideration are included in the transaction price to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur and when the uncertainty associated with the variable consideration is subsequently resolved. Product sales are recorded net of estimated government-mandated rebates and chargebacks, estimated product returns, and other deductions.

Provisions for returns and other adjustments are provided for in the period the related revenue is recorded, as estimated by management. These reserves are based on estimates of the amounts earned or to be claimed on the related sales and are reviewed periodically and adjusted as necessary. The Company’s estimates of government mandated rebates, chargebacks, estimated product returns, and other deductions depends on the identification of key customer contract terms and conditions, as well as estimates of sales volumes to different classes of payors. If actual results vary, the Company may need to adjust these estimates, which could have a material effect on earnings in the period of the adjustment.

Collaboration, License, and Royalty Revenue

The Company has certain license and collaboration agreements that are within the scope of Accounting Standards Codification, or ASC, 808, Collaborative Agreements, which provides guidance on the presentation and disclosure of collaborative arrangements. Generally, the classification of the transactions under the collaborative arrangements is determined based on the nature of contractual terms of the arrangement, along with the nature of the operations of the participants. The Company records its share of collaboration revenue, net of transfer pricing related to net sales in the period in which such sales occur, if the Company is considered as an agent in the arrangement. The Company is considered an agent when the collaboration partner controls the product before transfer to the customers and has the ability to direct the use of and obtain substantially all of the remaining benefits from the product. Funding received related to research and development services and commercialization costs is generally classified as a reduction of research and development expenses and selling, general and administrative expenses, respectively, in the Consolidated Statements of Operations, because the provision of such services for collaborative partners are not considered to be part of the Company’s ongoing major or central operations.

The Company utilizes certain information from its collaboration partners to record collaboration revenue, including revenue from the sale of the product, associated reserves on revenue, and costs incurred for development and sales activities. For the periods covered in the financial statements presented, there have been no material changes to prior period estimates of revenues and expenses. The Company also records royalty revenues under certain of the Company’s license or collaboration agreements in exchange for license of intellectual property.

The Company sold the right to receive certain royalty payments from net sales of Crysvita in certain territories to RPI Finance Trust, or RPI, an affiliate of Royalty Pharma, and to OCM LS23 Holdings LP, an investment vehicle for Ontario Municipal Employees Retirement System, or OMERS, as further described in “Note 10. Liabilities for Sales of Future Royalties.” The Company records the royalty revenue from the net sales of Crysvita in the applicable territories on a prospective basis as non-cash royalty revenue in the Consolidated Statements of Operations over the term of the applicable arrangement.

The terms of the Company’s collaboration and license agreements may contain multiple performance obligations, which may include licenses and research and development activities. The Company evaluates these agreements under ASC 606, Revenue from Contracts with Customers, or ASC 606, to determine the distinct performance obligations. The Company analogizes to ASC 606 for the accounting for distinct performance obligations for which there is a customer relationship. Prior to recognizing revenue, the Company makes estimates of the transaction price, including variable consideration that is subject to a constraint. Amounts of variable consideration are included in the transaction price to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur and when the uncertainty associated with the variable consideration is subsequently resolved. Total consideration may include nonrefundable upfront license fees, payments for research and development activities, reimbursement of certain third-party costs, payments based upon the achievement of specified milestones, and royalty payments based on product sales derived from the collaboration.

If there are multiple distinct performance obligations, the Company allocates the transaction price to each distinct performance obligation based on its relative standalone selling price. The standalone selling price is generally determined based on the prices charged to customers or using expected cost-plus margin. The Company estimates the efforts needed to complete the performance obligations and recognizes revenue by measuring the progress towards complete satisfaction of the performance obligations using input measures.

Deferred Compensation Plan

The Company maintains a nonqualified deferred compensation plan whereby certain employees and members of the board of directors are able to defer certain equity awards and other compensation. Amounts deferred are invested into shares of the Company's common stock, mutual funds, and other investment options. The plan complies with the provisions of Section 409A of the Internal Revenue Code. All of the various mutual funds held in the plan are classified as trading securities and recorded at fair value in other non-current assets in the Consolidated Balance Sheets with changes in fair value recognized as earnings in the period they occur. The short-term portion of the corresponding liability for the plan is included in accrued expenses. The long-term portion of the liability is included in other non-current liabilities in the Consolidated Balance Sheets. Certain equity awards deferred under the plan are required to be settled through the issuance of Company stock. These awards are recorded as treasury stock and deferred compensation obligation within stockholders’ equity.

Leases

Lease agreements are evaluated to determine whether an arrangement is or contains a lease in accordance with ASC 842, Leases. The Company determines if an arrangement includes a lease at inception. Right-of-use lease assets and lease liabilities are

recognized based on the present value of the future minimum lease payments over the lease term at the commencement date. The right-of-use lease asset includes any lease payments made and excludes lease incentives. Incremental borrowing rate is used in determining the present value of future payments. The Company applies a portfolio approach to the property leases to apply an incremental borrowing rate to leases with similar lease terms. The lease terms may include options to extend or terminate the lease. The Company recognizes the options to extend the lease as part of the right-of-use lease assets and lease liabilities only if it is reasonably certain that the option would be exercised. Lease expense for minimum lease payments is recognized on a straight-line basis over the non-cancelable lease term. The Company has elected to not separate lease and non-lease components. See “Note 9. Leases” for further disclosure.

Comprehensive Loss

Comprehensive loss is the change in stockholders’ equity from transactions and other events and circumstances other than those resulting from investments by stockholders and distributions to stockholders. The Company’s other comprehensive loss is comprised of unrealized gains and losses on investments in available-for-sale securities and foreign currency translation adjustments.

Research and Development

Research and development costs are expensed as incurred and consist of salaries and benefits, stock-based compensation expense, lab supplies and facility costs, as well as fees paid to other nonemployees and entities that conduct certain research and development activities on the Company’s behalf. Amounts incurred in connection with license agreements are also included in research and development expense. Nonrefundable advance payments for goods or services to be received in the future for use in research and development activities are deferred. The deferred amounts are expensed as the related goods are delivered or the services are performed.

Stock-Based Compensation

Stock-based awards issued to employees, including stock options, performance stock options, or PSOs, restricted stock units, or RSUs, and performance stock units, or PSUs are recorded at fair value as of the grant date and recognized as expense on a straight-line basis over the employee’s requisite service period (generally the vesting period). PSOs and PSUs vest only if certain specified criteria are achieved and the employees’ continued service requirements are met; therefore, the expense recognition occurs when the likelihood of the PSOs and PSUs being earned is deemed probable. Stock compensation expense on awards expected to vest is recognized net of estimated forfeitures.

Income Taxes

The Company uses the liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial reporting and the tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The Company must then assess the likelihood that the resulting deferred tax assets will be realized. A valuation allowance is provided when it is more likely than not that some portion or all of a deferred tax asset will not be realized. Due to the Company’s lack of earnings history, the net deferred tax assets have been fully offset by a valuation allowance.

In conjunction with the acquisition of Dimension Therapeutics, Inc., or Dimension, a deferred tax liability was recorded reflecting the tax impact of the difference between the book basis and tax basis of acquired IPR&D. Such deferred income tax liability is not used to offset deferred tax assets when analyzing the Company’s valuation allowance as the acquired IPR&D is considered to have an indefinite life until the Company completes or abandons development of the acquired IPR&D.

The Company recognizes benefits of uncertain tax positions if it is more likely than not that such positions will be sustained upon examination based solely on their technical merits, as the largest amount of benefit that is more likely than not to be realized upon the ultimate settlement. The Company’s policy is to recognize interest and penalties related to the underpayment of income taxes as a component of income tax expense or benefit. To date, there have been no interest or penalties charged in relation to the unrecognized tax benefits.

Foreign Currency

Assets and liabilities of non-U.S. subsidiaries that operate in a local currency environment, where the local currency is the functional currency, are translated to U.S. dollars at exchange rates in effect at the balance sheet date, with the resulting translation adjustments directly recorded to a separate component of accumulated other comprehensive loss. Income and expense accounts are translated at average exchange rates for the period. Transactions which are not in the functional currency of the entity are remeasured into the functional currency and gains or losses resulting from the remeasurement recorded in other income (expense).

Net Loss per Share

Basic net loss per share is calculated by dividing the net loss by the weighted-average number of shares of common stock outstanding during the period, without consideration for common stock equivalents. Shares of common stock into which pre-funded warrants may be exercised are considered outstanding for the purposes of computing basic net loss per share because the shares may be issued for little or no consideration, are fully vested and are exercisable after the original issuance date. Diluted net loss per share is the same as basic net loss per share, since the effects of potentially dilutive securities are antidilutive. In periods when we have incurred a net loss, options and warrants to purchase common stock are considered common stock equivalents, but have been excluded from the calculation of diluted net loss per share, as their effect is antidilutive.

Balance Sheet Components - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Schedule Of Available For Sale Securities [Line Items]
Depreciation expense	$ 22.2	$ 15.0	$ 12.9
Maximum
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale securities remaining contractual maturities	3 years

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
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-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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-Section 50
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-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 2
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
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-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
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-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

+ Details

Commitments and Contingencies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2023
Manufacturing and Services
Commitments And Contingencies Disclosure Line Items
Contractual Obligation Maturity Period	12 months

Stock-Based Awards - Summary of Stock-Based Compensation Recognized (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 135,213	$ 130,368	$ 104,979
Cost of sales
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	1,166	902	871
Research and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	74,531	74,464	59,097
Selling, general and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 59,516	$ 55,002	$ 45,011

Balance Sheet Components - Summary of Property, Plant and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 373,967	$ 323,107
Less accumulated depreciation	(83,401)	(63,381)
Property, plant and equipment, net	290,566	259,726
Building
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 181,356	$ 2,798
Building \| Minimum
Property Plant And Equipment [Line Items]
Property, plant and equipment, estimated useful lives (years)	20 years	20 years
Building \| Maximum
Property Plant And Equipment [Line Items]
Property, plant and equipment, estimated useful lives (years)	30 years	30 years
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 58,683	$ 43,941
Property, plant and equipment, estimated useful lives	us-gaap:UsefulLifeShorterOfTermOfLeaseOrAssetUtilityMember	us-gaap:UsefulLifeShorterOfTermOfLeaseOrAssetUtilityMember
Research and Development Equipment
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 56,347	$ 50,291
Property, plant and equipment, estimated useful lives (years)	5 years	5 years
Furniture and Office Equipment
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 6,419	$ 5,540
Property, plant and equipment, estimated useful lives (years)	5 years	5 years
Computer Equipment and Software
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 16,196	$ 13,876
Computer Equipment and Software \| Minimum
Property Plant And Equipment [Line Items]
Property, plant and equipment, estimated useful lives (years)	3 years	3 years
Computer Equipment and Software \| Maximum
Property Plant And Equipment [Line Items]
Property, plant and equipment, estimated useful lives (years)	5 years	5 years
Manufacturing Equipment
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 37,297	$ 570
Manufacturing Equipment \| Minimum
Property Plant And Equipment [Line Items]
Property, plant and equipment, estimated useful lives (years)	5 years	5 years
Manufacturing Equipment \| Maximum
Property Plant And Equipment [Line Items]
Property, plant and equipment, estimated useful lives (years)	15 years	15 years
Land
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 16,619	$ 16,619
Construction-in-progress
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	867	189,448
Other
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 183	$ 24

Stock-Based Awards - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Jun. 30, 2023	Feb. 01, 2021	Feb. 05, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total intrinsic value of options exercised	$ 4.9	$ 2.6	$ 38.8
Cash received from exercise of options	$ 2.7	$ 6.2	$ 36.6
weighted-average estimated fair value	$ 25.53	$ 34.77	$ 70.84
Total estimated fair value of options vested	$ 59.7	$ 58.7	$ 48.1
Total unrecognized compensation cost	219.8
Weighted-average period to recognize cost		2 years 2 months 12 days
Stock-based compensation capitalized to inventory	1.9	$ 2.2	1.7
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total fair value of shares vested	54.6	47.1	35.5
Aggregate intrinsic value	33.0	37.8	69.9
Performance Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total fair value of shares vested	3.9	1.6	9.2
Aggregate intrinsic value	1.3	$ 2.0	$ 18.9
Performance Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
weighted-average estimated fair value		$ 28.76
Total estimated fair value of options vested	$ 3.4
Maximum \| Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock based awards vesting period	4 years
Minimum \| Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock based awards vesting period	1 year
2014 Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share of common stock authorized for future issuance						2,250,000
Automatic increases in shares available for grant effective date	Jan. 01, 2015
Shares available for grant, ending date	Jun. 07, 2023
2023 Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share of common stock authorized for future issuance				4,500,000
2023 Plan and Inducement Plan \| Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Option vesting rights, percentage			25.00%
Stock based awards vesting period			4 years
2023 Plan and Inducement Plan \| Maximum \| Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award expiration period			10 years
2023 Plan and Inducement Plan \| First Anniversary \| Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Option vesting rights, percentage			25.00%
2023 Plan and Inducement Plan \| Shares Vesting Monthly After First Anniversary \| Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Option vesting rights, percentage			2.08%
2014 Equity Incentive, 2023 Incentive and Employment Inducement Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share of common stock authorized for future issuance	19,610,125
2014 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share of common stock authorized for future issuance	6,609,795
Percentage of statutory stock awards	85.00%
Common stock shares issued	195,462
Employment Inducement Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share of common stock available for grant					850,000

Income Taxes - Components of Company's Income Tax Provision (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Current provision for income taxes:
State	$ (3,187)	$ 6,062	$ (14)
International	3,127	1,274	1,058
Total current tax provision	(60)	7,336	1,044
Deferred tax provision:
State	(1,608)	(1,640)
International	(157)
Total deferred tax provision	(1,765)	(1,640)
Total (benefit from) provision for income taxes	$ (1,825)	$ 5,696	$ 1,044

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References + Details

License and Research Agreements - Mereo - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development		$ 648,449	$ 705,789	$ 497,153
License and Collaboration Agreement \| Mereo
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development		$ 9,000	$ 0	$ 50,000
Payments made under agreement	$ 50,000
License and Collaboration Agreement \| Maximum \| Mereo
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Future contingent milestone payments	$ 254,000

Commitments and Contingencies

12 Months Ended

Dec. 31, 2023

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

15.

Commitments and Contingencies

The Company has various manufacturing, construction, clinical, research, and other contracts with vendors in the conduct of the normal course of its business. Other than as noted below, contracts are terminable, with varying provisions regarding termination. If a contract with a specific vendor were to be terminated, the Company would only be obligated for the products or services that the Company had received at the time the termination became effective.

Manufacturing and service contract obligations primarily relate to the manufacture of inventory for our approved products, the majority of which are due in the next 12 months.

As of December 31, 2023, the aggregate payments under contractually-binding manufacturing and service agreements are as follows (in thousands):


	Year Ended December 31,
	2024		2025		Total
Manufacturing and Services	$	27,899	$	5,718	$	33,617

The terms of certain of the Company’s licenses, royalties, development and collaboration agreements, as well as other research and development activities, require the Company to pay potential future milestone payments based on product development success. The amount and timing of such obligations are unknown or uncertain. These potential obligations are further described in “Note 8. License and Research Agreements.”

See “Note 9. Leases” for lease commitments.

Contingencies

While there are no material legal proceedings the Company is aware of, the Company may become party to various claims and complaints arising in the ordinary course of business. Management does not believe that any ultimate liability resulting from any of these potential claims will have a material adverse effect on its results of operations, financial position, or liquidity. However, management cannot give any assurance regarding the ultimate outcome of these claims, and their resolution could be material to operating results for any particular period, depending upon the level of income for the period.

Guarantees and Indemnifications

The Company indemnifies each of its directors and officers for certain events or occurrences, subject to certain limits, while the director or officer is or was serving at the Company’s request in such capacity, as permitted under Delaware law and in accordance with its certificate of incorporation and bylaws. The term of the indemnification period lasts as long as a director or officer may be subject to any proceeding arising out of acts or omissions of such director and officer in such capacity. The maximum amount of potential future indemnification is unlimited; however, the Company currently holds director liability insurance. This insurance allows the transfer of risk associated with the Company’s exposure and may enable it to recover a portion of any future amounts paid. The Company believes that the fair value of these indemnification obligations is minimal. Accordingly, it has not recognized any liabilities relating to these obligations for any period presented.

Revenue - Additional Information (Details)	Dec. 31, 2023	Dec. 31, 2022
Customer One
Disaggregation of Revenue [Line Items]
Percentage of gross accounts receivable balance	53.00%	68.00%

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

License and Research Agreements - Daiichi Sankyo - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		3 Months Ended	12 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Mar. 31, 2020	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaborative Arrangement, Revenue Not from Contract with Customer, Statement of Income or Comprehensive Income [Extensible Enumeration]				Revenue
Daiichi Sankyo
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Deferred Revenue balance				$ 0.0	$ 1.5
Deferred Revenue Recognized				1.5	$ 7.7	$ 85.0
License and Technology Access Agreement \| Daiichi Sankyo
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Deferred Revenue balance				25.0
Upfront payment received				125.0
License and Technology Access Agreement \| Daiichi Sankyo \| Licenses Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue recognized				$ 183.3
Stock Purchase Agreement \| Daiichi Sankyo
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Issuance of common stock in connection with license agreement, net of issuance costs, shares		1,243,913
Proceeds from issuance of common stock in connection with license agreement			$ 75.0
Issuance of common stock in connection with license agreement, net of issuance costs			$ 55.3
Stock price		$ 44.43	$ 44.43
Premium from stock purchase agreement			$ 19.7
Sublicense Agreement \| Daiichi Sankyo
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront payment received	$ 8.0

Income Taxes - Components of Company's Loss Before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Domestic	$ 608,166	$ 703,411	$ 455,314
Foreign	298	(1,686)	(2,333)
Total loss before income taxes	$ 608,464	$ 701,725	$ 452,981

- Definition

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(11))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483586/944-220-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 30
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-30

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 31
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-31

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 235
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-05(b)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479557/942-235-S99-1

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 25
-Paragraph 1
-SubTopic 20
-Topic 940
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481913/940-20-25-1

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(10))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(15))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483589/942-220-S99-1

+ Details

Intangible Assets, Net - Summary of Company's Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Schedule of Finite and Indefinite Lived Intangible Assets [Line Items]
Intangible assets - Gross carrying amount	$ 173,775	$ 163,775
Intangible assets - Accumulated Amortization	(7,504)	(3,670)
Intangible assets - Net Carrying Amount	166,271	160,105
Indefinite-lived Intangible Assets
Schedule of Finite and Indefinite Lived Intangible Assets [Line Items]
Intangible assets - Gross carrying amount	129,000	129,000
Intangible assets - Net Carrying Amount	129,000	129,000
Finite lived intangible assets
Schedule of Finite and Indefinite Lived Intangible Assets [Line Items]
Intangible assets - Gross carrying amount	$ 44,775	$ 34,775
Intangible assets - Weighted Average Life	9 years 7 months 6 days	9 years 10 months 24 days
Intangible assets - Accumulated Amortization	$ (7,504)	$ (3,670)
Intangible assets - Net Carrying Amount	$ 37,271	$ 31,105

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 213,584	$ 132,944
Marketable debt securities	363,625	614,818
Accounts receivable, net	73,390	40,445
Inventory	33,969	26,766
Other assets	47,616	68,926
Total current assets	732,184	883,899
Property, plant, and equipment, net	290,566	259,726
Marketable debt securities	199,901	148,970
Intangible assets, net	166,271	160,105
Goodwill	44,406	44,406
Other assets	57,685	48,338
Total assets	1,491,013	1,545,444
Current liabilities:
Accounts payable	42,114	43,274
Accrued liabilities	196,486	204,678
Contract liabilities	0	1,479
Lease liabilities	12,595	11,779
Liabilities for sales of future royalties	29,242	0
Total current liabilities	280,437	261,210
Lease liabilities	30,574	19,814
Deferred tax liabilities	30,058	31,667
Liabilities for sales of future royalties	862,325	875,439
Other liabilities	12,205	4,820
Total liabilities	1,215,599	1,192,950
Commitments and contingencies (Notes 9 and 15)
Stockholders’ equity:
Preferred stock, par value of $0.001 per share - 25,000,000 shares authorized; nil outstanding in 2023 and in 2022	0	0
Common stock, par value of $0.001 per share - 250,000,000 shares authorized;outstanding - 82,315,590 in 2023 and 70,197,297 in 2022	82	70
Treasury stock, at cost, 9,559 in 2023 and nil in 2022	(432)	0
Deferred compensation obligation	432	0
Additional paid-in capital	3,662,346	3,140,019
Accumulated other comprehensive income (loss)	647	(6,573)
Accumulated deficit	(3,387,661)	(2,781,022)
Total stockholders’ equity	275,414	352,494
Total liabilities and stockholders’ equity	$ 1,491,013	$ 1,545,444

License and Research Agreements - Kyowa Kirin Co., Ltd. - Additional Information (Details) - Kyowa Kirin Collaboration - License Agreement - USD ($) $ in Millions		12 Months Ended	113 Months Ended
	Jul. 01, 2022	Dec. 31, 2023	Dec. 31, 2022
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Profit loss sharing percentage on net sales		30.00%	35.00%
Minimum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Tiered double-digit revenue share percentage entitled to receive		20.00%
Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Tiered double-digit revenue share percentage entitled to receive		30.00%
Other Current Assets
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
License agreement other receivables		$ 1.1	$ 6.4
Profit Share Revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
License agreement accounts receivable		39.2	27.5
Commercial And Development Activity Reimbursements [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
License agreement accrued liabilities		$ 5.3	$ 3.1
Profit Share Territory
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Remaining profit or loss share percentage on commercializing products		50.00%
Percentage of right to receive royalty payments on net sales	30.00%
Royalty Revenue in European Territory
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Percentage of royalty on net sales receives		10.00%

Net Loss per Share (Tables)

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

Computation of Basic and Diluted Net Loss per Share

The following table sets forth the computation of the basic and diluted net loss per share during the years ended December 31, 2023, 2022, and 2021 (in thousands, except share and per share data):


	Year Ended December 31,
	2023			2022			2021
Numerator:
Net loss	$	(606,639	)	$	(707,421	)	$	(454,025	)
Denominator:
Weighted-average shares used to compute net loss per share, basic and diluted		73,543,862			69,914,225			67,795,540
Net loss per share, basic and diluted	$	(8.25	)	$	(10.12	)	$	(6.70	)

Outstanding Shares of Common Stock Equivalents Excluded from Computation of Diluted Net Loss per Share

The following weighted-average outstanding common stock equivalents were excluded from the computation of diluted net loss per share for the periods presented because including them would have been antidilutive:


	Year Ended December 31,
	2023		2022		2021
Options to purchase common stock, restricted stock units, and performance stock units		14,152,286		11,290,935		8,214,063
Employee stock purchase plan		8,450		7,581		3,511
		14,160,736		11,298,516		8,217,574

Liabilities for Sales of Future Royalties - Schedule of Activity Within Liability Related to Sale of Future Royalties (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Liability For Sale Of Future Royalties [Line Items]
Liability for sale of future royalties at beginning of year	$ 875,439	$ 351,786
Net proceeds from sale of future royalties	0	490,950	$ 0
Royalty revenue	(59,307)	(21,692)
Non-cash interest expense	75,435	54,395
Liability for sale of future royalties at end of year	891,567	875,439	351,786
RPI Finance Trust (RPI)
Liability For Sale Of Future Royalties [Line Items]
Liability for sale of future royalties at beginning of year	365,189	351,786
Net proceeds from sale of future royalties		0
Royalty revenue	(20,783)	(21,692)
Non-cash interest expense	32,235	35,095
Liability for sale of future royalties at end of year	376,641	365,189	351,786
OMERS
Liability For Sale Of Future Royalties [Line Items]
Liability for sale of future royalties at beginning of year	510,250	0
Net proceeds from sale of future royalties		490,950
Royalty revenue	(38,524)	0
Non-cash interest expense	43,200	19,300
Liability for sale of future royalties at end of year	$ 514,926	$ 510,250	$ 0

Revenue - Summary of Disaggregation of Total Revenues from Customers (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation Of Revenue [Line Items]
Total revenues	$ 434,249	$ 363,329	$ 351,406
Collaboration and license
Disaggregation Of Revenue [Line Items]
Total revenues	71,184	222,710	256,438
Collaboration and license \| Crysvita
Disaggregation Of Revenue [Line Items]
Total revenues	69,705	215,024	171,198
Collaboration and license \| Crysvita \| Royalty Revenue in European Territory
Disaggregation Of Revenue [Line Items]
Total revenues	0	0	244
Collaboration and license \| Daiichi Sankyo
Disaggregation Of Revenue [Line Items]
Total revenues	1,479	7,686	84,996
Product Revenue
Disaggregation Of Revenue [Line Items]
Total revenues	180,413	118,927	77,017
Product Revenue \| Crysvita
Disaggregation Of Revenue [Line Items]
Total revenues	75,697	42,678	21,422
Product Revenue \| Mepsevii
Disaggregation Of Revenue [Line Items]
Total revenues	30,441	20,637	16,035
Product Revenue \| Dojolvi
Disaggregation Of Revenue [Line Items]
Total revenues	70,633	55,612	39,560
Product Revenue \| Evkeeza
Disaggregation Of Revenue [Line Items]
Total revenues	3,642	0	0
Royalty revenue
Disaggregation Of Revenue [Line Items]
Total revenues	182,652	21,692	17,951
Royalty revenue \| Crysvita
Disaggregation Of Revenue [Line Items]
Total revenues	$ 182,652	$ 21,692	$ 17,951

Liabilities for Sales of Future Royalties (Tables)

12 Months Ended

Dec. 31, 2023

Deferred Revenue Disclosure [Abstract]

Schedule of Activity Within Liability for Sale of Future Royalties

The following table shows the activity within the liability account (in thousands):



	Liabilities for Sales of Future Royalties
	RPI			OMERS			Total
December 31, 2021	$	351,786		$	—		$	351,786
Net proceeds from sale of future royalties		—			490,950			490,950
Royalty revenue		(21,692	)		—			(21,692	)
Non-cash interest expense		35,095			19,300			54,395
December 31, 2022		365,189			510,250			875,439
Royalty revenue		(20,783	)		(38,524	)		(59,307	)
Non-cash interest expense		32,235			43,200			75,435
December 31, 2023	$	376,641		$	514,926		$	891,567

Balance Sheet Components - Summary of Inventory (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Inventory, Net [Abstract]
Work-in-process	$ 18,859	$ 17,486
Finished goods	15,110	9,280
Total inventory	$ 33,969	$ 26,766

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating activities:
Net loss	$ (606,639)	$ (707,421)	$ (454,025)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	135,227	130,377	104,952
Acquired in-process research and development	0	75,033	0
Amortization of premium (discount) on marketable debt securities, net	(12,842)	2,699	6,606
Depreciation and amortization	26,006	18,220	13,239
Change in fair value of equity investments	(397)	19,299	42,063
Non-cash collaboration royalty revenue	(69,364)	(21,692)	(17,951)
Non-cash interest expense on liabilities for sales of future royalties	66,004	43,015	29,422
Other	2,300	(230)	235
Changes in operating assets and liabilities:
Accounts receivable	(22,778)	(12,068)	(5,432)
Inventory	(6,930)	(9,701)	(3,117)
Other assets	15,325	3,798	(29,508)
Accounts payable, accrued, and other liabilities	2,380	87,442	32,313
Contract liabilities, net	(1,479)	(7,597)	(57,492)
Deferred tax liabilities	(1,619)	(1,639)	0
Net cash used in operating activities	(474,806)	(380,465)	(338,695)
Investing activities:
Purchase of property, plant, and equipment	(44,267)	(116,123)	(73,093)
Acquisition, net of cash acquired	0	(75,025)	0
Purchase of marketable debt securities	(526,382)	(614,735)	(1,012,187)
Proceeds from sale of marketable debt securities	50,672	84,275	92,896
Proceeds from sale of equity investments	0	10,094	79,843
Proceeds from maturities of marketable debt securities	695,525	450,706	718,111
Payment for intangible asset	(2,500)	(30,000)	0
Other	(5,048)	(844)	(942)
Net cash provided by (used in) investing activities	168,000	(291,652)	(195,372)
Financing activities:
Proceeds from the sale of future royalties, net	0	490,950	0
Proceeds from the issuance of common stock and pre-funded warrants in connection with underwritten public offerings, net of issuance costs	326,456	0	0
Proceeds from the issuance of common stock in connection with at-the-market offering, net of issuances costs	53,299	0	78,943
Proceeds from the issuance of common stock from exercise of warrants and equity plan awards, net	8,415	10,813	40,101
Other	(28)	(555)	(492)
Net cash provided by financing activities	388,142	501,208	118,552
Effect of exchange rate changes on cash	462	(1,075)	(1,194)
Net increase (decrease) in cash, cash equivalents, and restricted cash	81,798	(171,984)	(416,709)
Cash, cash equivalents, and restricted cash at beginning of year	137,601	309,585	726,294
Cash, cash equivalents, and restricted cash at end of year	219,399	137,601	309,585
Supplemental disclosures of non-cash investing and financing information:
Acquired lease liabilities arising from obtaining right-of-use assets and property, plant, and equipment	22,162	1,168	3,142
Costs of property and equipment included in accounts payable, accrued, and other liabilities	1,577	17,963	18,993
Non-cash interest expense on liabilities for sales of future royalties capitalized during the year into ending property, plant and equipment	$ 9,431	$ 11,380	$ 4,650

Fair Value Measurements - Additional Information (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Short-Term Debt [Member]
Schedule Of Available For Sale Securities [Line Items]
Deferred compensation liabilities	$ 0.2	$ 0.0
Long-Term Debt [Member]
Schedule Of Available For Sale Securities [Line Items]
Deferred compensation liabilities	$ 10.1	$ 4.7

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Net Loss per Share

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

Net Loss per Share

17.

Net Loss per Share

The following table sets forth the computation of the basic and diluted net loss per share during the years ended December 31, 2023, 2022, and 2021 (in thousands, except share and per share data):


	Year Ended December 31,
	2023			2022			2021
Numerator:
Net loss	$	(606,639	)	$	(707,421	)	$	(454,025	)
Denominator:
Weighted-average shares used to compute net loss per share, basic and diluted		73,543,862			69,914,225			67,795,540
Net loss per share, basic and diluted	$	(8.25	)	$	(10.12	)	$	(6.70	)


	Year Ended December 31,
	2023		2022		2021
Options to purchase common stock, restricted stock units, and performance stock units		14,152,286		11,290,935		8,214,063
Employee stock purchase plan		8,450		7,581		3,511
		14,160,736		11,298,516		8,217,574

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pay vs Performance Disclosure
Net Income (Loss)	$ (606,639)	$ (707,421)	$ (454,025)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 28: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenues:
Total revenues	$ 434,249	$ 363,329	$ 351,406
Operating expenses:
Cost of sales	45,209	28,320	16,008
Research and development	648,449	705,789	497,153
Selling, general and administrative	309,799	278,139	219,982
Total operating expenses	1,003,457	1,012,248	733,143
Loss from operations	(569,208)	(648,919)	(381,737)
Interest income	26,688	11,074	1,928
Change in fair value of equity investments	397	(19,299)	(42,063)
Non-cash interest expense on liabilities for sales of future royalties	(66,004)	(43,015)	(29,422)
Other expense	(337)	(1,566)	(1,687)
Loss before income taxes	(608,464)	(701,725)	(452,981)
Benefit from (provision for) income taxes	1,825	(5,696)	(1,044)
Net loss	$ (606,639)	$ (707,421)	$ (454,025)
Net loss per share, basic	$ (8.25)	$ (10.12)	$ (6.7)
Net loss per share, diluted	$ (8.25)	$ (10.12)	$ (6.7)
Shares used in computing net loss per share, Basic	73,543,862	69,914,225	67,795,540
Shares used in computing net loss per share, Diluted	73,543,862	69,914,225	67,795,540
Product sales
Revenues:
Total revenues	$ 180,413	$ 118,927	$ 77,017
Royalty revenue
Revenues:
Total revenues	182,652	21,692	17,951
Collaboration and license
Revenues:
Total revenues	$ 71,184	$ 222,710	$ 256,438

Liabilities for Sales of Future Royalties - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended		12 Months Ended			49 Months Ended
	Jul. 31, 2022	Dec. 31, 2019	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2023
Liability For Sale Of Future Royalties [Line Items]
Proceeds from the sale of future royalties, net			$ 0	$ 490,950	$ 0
Non-cash collaboration royalty revenue			$ 69,364	21,692	$ 17,951
RPI Finance Trust (RPI)
Liability For Sale Of Future Royalties [Line Items]
Proceeds from the sale of future royalties, net				0
OMERS
Liability For Sale Of Future Royalties [Line Items]
Proceeds from the sale of future royalties, net				$ 490,950
Royalty Purchase Agreement
Liability For Sale Of Future Royalties [Line Items]
Profit loss sharing percentage on net sales	30.00%
Royalty Purchase Agreement \| RPI Finance Trust (RPI)
Liability For Sale Of Future Royalties [Line Items]
Proceeds from sale of future royalties		$ 320,000
Royalty payment termination description			The agreement with RPI will automatically terminate, and the payment of royalties to RPI will cease, in the event aggregate royalty payments received by RPI are equal to or greater than $608.0 million prior to December 31, 2030, or in the event aggregate royalty payments received by RPI are less than $608.0 million prior to December 31, 2030, or when aggregate royalty payments received by RPI are equal to $800.0 million.
Royalties transaction costs net		5,800
Proceeds from the sale of future royalties, net		314,200
Effective annual interest rate			6.20%			6.20%
Non-cash collaboration royalty revenue						$ 73,400
Royalty Purchase Agreement \| OMERS
Liability For Sale Of Future Royalties [Line Items]
Proceeds from sale of future royalties	$ 500,000
Royalty payment termination description	In July 2022, the Company entered into a Royalty Purchase Agreement with OMERS. Pursuant to the agreement, OMERS paid $500.0 million to the Company in consideration for the right to receive 30% of the future royalty payments due to the Company from KKC based on net sales of Crysvita in the U.S. and Canada under the terms of the KKC Collaboration Agreement. The calculation of royalty payments to OMERS is based on net sales of Crysvita beginning in April 2023 and will expire upon the earlier of the date on which aggregate payments received by OMERS equals $725.0 million or the date the final royalty payment is made to the Company under the KKC Collaboration Agreement.
Royalty agreement termination threshold amount	$ 725,000
Payment from sale of future royalties	500,000
Royalties transaction costs net	$ 9,100
Proceeds from the sale of future royalties, net		$ 491,000
Effective annual interest rate			7.80%			7.80%
Non-cash collaboration royalty revenue						$ 8,600
Royalty Purchase Agreement \| Minimum \| RPI Finance Trust (RPI)
Liability For Sale Of Future Royalties [Line Items]
Royalty agreement termination threshold amount			$ 608,000			608,000
Royalty Purchase Agreement \| Maximum \| RPI Finance Trust (RPI)
Liability For Sale Of Future Royalties [Line Items]
Royalty agreement termination threshold amount			$ 800,000			$ 800,000

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Basis of Consolidation

The Consolidated Financial Statements include the accounts of Ultragenyx Pharmaceutical Inc. and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated.

Use of Estimates

Cash, Cash Equivalents, and Restricted Cash

Restricted cash primarily consists of money market accounts used as collateral for the Company’s obligations under its facility leases and the gene therapy building construction project.


	December 31,
	2023		2022		2021
Cash and cash equivalents	$	213,584	$	132,944	$	307,584
Restricted cash included in other current assets		2,008		862		—
Restricted cash included in other non-current assets		3,807		3,795		2,001
Total cash, cash equivalents, and restricted cash shown in the statements of cash flows	$	219,399	$	137,601	$	309,585

Marketable Debt Securities

Equity Investments

Concentration of Credit Risk, Credit Losses, and Other Risks and Uncertainties

Inventory

Property, Plant, and Equipment

Intangible Assets

Goodwill

Impairment of Long-Lived Assets

Accruals of Research and Development Costs

Revenue Recognition

Product Sales

Collaboration, License, and Royalty Revenue

Deferred Compensation Plan

Leases

Comprehensive Loss

Research and Development

Stock-Based Compensation

Income Taxes

Foreign Currency

Net Loss per Share

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Dec. 31, 2023 shares
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	On November 10, 2023, Corsee Sanders, Ph.D., a member of the Company’s Board of Directors, adopted a trading arrangement intended to satisfy the affirmative defense of Rule 10b5-1(c), to sell up to 2,322 shares of the Company’s common stock through July 12, 2024, subject to certain conditions. On December 7, 2023, Matthew Fust, a member of the Company’s Board of Directors, adopted a trading arrangement intended to satisfy the affirmative defense of Rule 10b5-1(c), to sell up to 12,195 shares of the Company’s common stock through December 6, 2024, subject to certain conditions.
Corsee Sanders [Member]
Trading Arrangements, by Individual
Name	Corsee Sanders
Title	member of the Company’s Board of Directors
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	November 10, 2023
Aggregate Available	2,322
Matthew Fust [Member]
Trading Arrangements, by Individual
Name	Matthew Fust
Title	member of the Company’s Board of Directors
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	December 7, 2023
Aggregate Available	12,195

License and Research Agreements - Saint Louis University - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
Saint Louis University
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone payments paid	$ 0.1

Revenue

12 Months Ended

Dec. 31, 2023

Revenue from Contract with Customer [Abstract]

Revenue

The following table disaggregates total revenues from external customers by product sales, royalty revenue, and collaboration and license revenue (in thousands):


	Year Ended December 31,
	2023		2022		2021

Product sales:
Crysvita	$	75,697	$	42,678	$	21,422
Mepsevii		30,441		20,637		16,035
Dojolvi		70,633		55,612		39,560
Evkeeza		3,642		—		—
Total product sales		180,413		118,927		77,017
Crysvita royalty revenue		182,652		21,692		17,951
Collaboration and license revenue:
Crysvita collaboration revenue in Profit-Share Territory		69,705		215,024		171,198
Crysvita royalty revenue in European Territory		—		—		244
Daiichi Sankyo		1,479		7,686		84,996
Total collaboration and license revenue		71,184		222,710		256,438
Total revenues	$	434,249	$	363,329	$	351,406

The following table disaggregates total revenues based on geographic location (in thousands):


	Year Ended December 31,
	2023		2022		2021
North America	$	307,149	$	281,088	$	301,110
Latin America		77,342		44,711		23,636
Europe		47,534		36,369		26,660
Japan		2,224		1,161		—
Total revenues	$	434,249	$	363,329	$	351,406

The following table presents the activity and ending balances for sales-related accruals and allowances (in thousands):


	Year Ended December 31,
	2023			2022			2021
Balance of product sales reserve at beginning of year	$	11,487		$	7,181		$	3,913
Provisions		18,761			13,525			9,586
Payments		(12,746	)		(9,613	)		(6,120	)
Adjustments		(473	)		394			(198	)
Balance of product sales reserve at end of year	$	17,029		$	11,487		$	7,181

The following table presents changes in the contract liabilities for the years ended December 31, 2023 and 2022 (in thousands):


	Year Ended December 31,
	2023			2022
Balance of contract liabilities at beginning of period	$	1,479		$	9,076
Additions		—			89
Deductions		(1,479	)		(7,686	)
Balance of contract liabilities at end of period, net	$	—		$	1,479

See Note 8 for additional details on contract liabilities activities.

The Company’s largest accounts receivable balance was from a collaboration partner and was 53% and 68% of the total accounts receivable balance as of December 31, 2023 and 2022, respectively.

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-13

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Topic 606
-Publisher FASB
-URI https://asc.fasb.org//606/tableOfContent

+ Details

Income Taxes - Effective Tax Rate of Provision for Income Taxes from Federal Statutory Rate (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Federal statutory income tax rate	21.00%	21.00%	21.00%
State income taxes, net of federal benefit	0.80%	(0.40%)
Federal tax credits	7.30%	5.90%	7.20%
Other	(0.70%)	(0.10%)	0.50%
Nondeductible permanent items	(0.30%)	(0.60%)	(0.80%)
Stock-based compensation	(1.80%)	(1.20%)	1.30%
Uncertain tax positions	(1.40%)	(1.20%)	(1.40%)
Change in valuation allowance	(24.10%)	(24.00%)	(27.90%)
Foreign rate differential	(0.50%)	(0.20%)	(0.10%)
Provision for income taxes	0.30%	(0.80%)	(0.20%)

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Summary of Reconciliation of Cash, Cash Equivalents and Restricted Cash


	December 31,
	2023		2022		2021
Cash and cash equivalents	$	213,584	$	132,944	$	307,584
Restricted cash included in other current assets		2,008		862		—
Restricted cash included in other non-current assets		3,807		3,795		2,001
Total cash, cash equivalents, and restricted cash shown in the statements of cash flows	$	219,399	$	137,601	$	309,585

License and Research Agreements - Schedule of Changes in Fair Value of Equity Investment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Common stock, Beginning balance	$ 884,017
Common stock, Ending balance	749,239	$ 884,017
Arcturus \| Common Stock
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Common stock, Beginning balance	$ 0	18,505
Common stock, Change in fair value		(8,411)
Common stock, Sale of shares		(10,094)
Common stock, Ending balance		$ 0

Leases (Tables)

12 Months Ended

Dec. 31, 2023

Lessee Disclosure [Abstract]

Summary of Components of Lease Expense

The components of lease expense were as follows (in thousands):


	Year Ended December 31,
	2023		2022		2021
Operating lease expense	$	12,883	$	11,775	$	11,209
Variable lease expense		5,272		4,785		4,142
Financing:
Amortization		203		343		310
Interest expense		—		37		58
Total	$	18,358	$	16,940	$	15,719

Schedule of Maturities of Lease Liabilities and the Reconciliation of Lease Liabilities

The following table summarizes maturities of lease liabilities and the reconciliation of lease liabilities as of December 31, 2023:


Year Ending December 31,	Operating
2024	$	16,234
2025		11,932
2026		8,430
2027		5,867
2028		5,887
Thereafter		6,009
Total future lease payments		54,359
Less: Amount representing interest		(11,190	)
Present value of future lease payments		43,169
Less: Lease liabilities, current		(12,595	)
Lease liabilities, non-current	$	30,574

Leases - Summary of Components of Lease Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Lease, Cost [Abstract]
Operating lease expense	$ 12,883	$ 11,775	$ 11,209
Variable lease expense	5,272	4,785	4,142
Financing:
Amortization	203	343	310
Interest expense	0	37	58
Total	$ 18,358	$ 16,940	$ 15,719

Accumulated Other Comprehensive Income (Loss) - Schedule of Total Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Cumulative foreign currency translation adjustment	$ (606)	$ (845)
Unrealized gain (loss) on securities available-for-sale	1,253	(5,728)
Total accumulated other comprehensive income (loss)	$ 647	$ (6,573)

- Definition

Amount, after tax, of accumulated increase (decrease) in equity from transaction and other event and circumstance from nonowner source.

+ References + Details

Leases

12 Months Ended

Dec. 31, 2023

Lessee Disclosure [Abstract]

Leases

The Company leases office space and research, testing and manufacturing laboratory space in various facilities in Novato and Brisbane, California, in Somerville, and Woburn, Massachusetts, and in certain foreign countries, under operating agreements expiring at various dates through 2029. Certain lease agreements include options for the Company to extend the lease for multiple renewal periods and provide for annual minimum increases in rent, usually based on a consumer price index or annual minimum increases. None of these optional periods have been considered in the determination of the right-of-use lease asset or the lease liability for the leases as the Company did not consider it reasonably certain that it would exercise any such options. The Company recognizes lease expense on a straight-line basis over the non-cancelable term of its operating leases. The variable lease expense primarily consists of common area maintenance and other operating costs.

The components of lease expense were as follows (in thousands):


	Year Ended December 31,
	2023		2022		2021
Operating lease expense	$	12,883	$	11,775	$	11,209
Variable lease expense		5,272		4,785		4,142
Financing:
Amortization		203		343		310
Interest expense		—		37		58
Total	$	18,358	$	16,940	$	15,719

Cash paid for amounts included in the measurement of operating lease liabilities for the years ended December 31, 2023, 2022, and 2021 was $13.4 million, $13.1 million, and $11.8 million, respectively, and was included in net cash used in operating activities in the Consolidated Statements of Cash Flows.

Right-of-use lease assets were $23.9 million and $26.0 million as of December 31, 2023 and 2022, respectively, and were included in other non-current assets on the Consolidated Balance Sheets.

The following table summarizes maturities of lease liabilities and the reconciliation of lease liabilities as of December 31, 2023:


Year Ending December 31,	Operating
2024	$	16,234
2025		11,932
2026		8,430
2027		5,867
2028		5,887
Thereafter		6,009
Total future lease payments		54,359
Less: Amount representing interest		(11,190	)
Present value of future lease payments		43,169
Less: Lease liabilities, current		(12,595	)
Lease liabilities, non-current	$	30,574

Lease liabilities are based on the net present value of the remaining lease payments over the remaining lease term. For the years ended December 31, 2023 and 2022, the weighted-average remaining operating lease terms were 4.5 years and 3.0 years, the weighted-average remaining financing lease terms were nil and 2.8 years, the weighted-average discount rates used to determine the lease liability for operating leases were 9.6% and 6.7%, and the weighted-average discount rates used to determine the lease liability for finance leases were nil and 5.1% respectively.

Accumulated Other Comprehensive Income (Loss)

12 Months Ended

Dec. 31, 2023

Other Comprehensive Income (Loss), Net of Tax [Abstract]

Accumulated Other Comprehensive Income (Loss)

18.

Accumulated Other Comprehensive Income (Loss)

Total accumulated other comprehensive income (loss) consisted of the following (in thousands):


	Year Ended December 31,
	2023			2022
Cumulative foreign currency translation adjustment	$	(606	)	$	(845	)
Unrealized gain (loss) on securities available-for-sale		1,253			(5,728	)
Total accumulated other comprehensive income (loss)	$	647		$	(6,573	)

Stock-Based Awards - Summary of Activity Under Stock Option Plans Including 2011 Plan and 2014 Plan and 2023 Plan (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-Based Payment Arrangement [Abstract]
Number of Options, Outstanding, Beginning Balance	7,773,367
Number of Options, Options granted	2,123,256
Number of Options, Options exercised	(209,793)
Number of Options, Options cancelled	(899,118)
Number of Options, Outstanding, Ending Balance	8,787,712	7,773,367
Vested and exercisable December 31, 2023	5,415,110
Vested and expected to vest December 31, 2023	8,461,973
Weighted Average Exercise Price, Outstanding, Beginning Balance	$ 72.56
Weighted Average Exercise Price, Options granted	45.05
Weighted Average Exercise Price, Options exercised	13.07
Weighted Average Exercise Price, Options cancelled	71.56
Weighted Average Exercise Price, Outstanding, Ending Balance	67.43	$ 72.56
Weighted- Average Exercise Price,Weighted Average Exercise Price	73.28
Weighted Average Exercise Price, Vested and expected to vest December 31, 2023	$ 67.96
Weighted Average Remaining Contractual Term (Years), Outstanding	6 years 4 months 20 days	6 years 7 months 6 days
Weighted Average Remaining Contractual Term (Years), Vested and exercisable - December 31, 2023	4 years 11 months 15 days
Weighted-Average Remaining Contractual Term,Vested and expected to vest December 31, 2023	6 years 3 months 14 days
Aggregate Intrinsic Value, Outstanding	$ 7,558	$ 8,476
Aggregate Intrinsic Value, Vested and exercisable - December 31, 2023	1,214
Aggregate Intrinsic Value, Vested and expected to vest - December 31, 2023	$ 6,794

License and Research Agreements - University of Pennsylvania - Additional Information (Details) - University of Pennsylvania School of Medicine (Penn) $ in Millions	Dec. 31, 2023 USD ($)
Research Collaboration and License Agreement Development Milestones
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Future contingent milestone payments	$ 5.0
Research Collaboration and License Agreement Commercial Milestones
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Future contingent milestone payments	$ 25.0

Income Taxes

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Income Taxes

14.

Income Taxes

The components of the Company’s loss before income taxes were as follows (in thousands):


	Year Ended December 31,
	2023		2022			2021
Domestic	$	608,166	$	703,411		$	455,314
Foreign		298		(1,686	)		(2,333	)
Total loss before income taxes	$	608,464	$	701,725		$	452,981

The components of the Company’s income tax provision were as follows (in thousands):


	Year Ended December 31,
	2023			2022			2021
Current provision for income taxes:
Federal	$	—		$	—		$	—
State		(3,187	)		6,062			(14	)
International		3,127			1,274			1,058
Total current tax provision		(60	)		7,336			1,044
Deferred tax provision:
Federal		—			—			—
State		(1,608	)		(1,640	)		—
International		(157	)		—			—
Total deferred tax provision		(1,765	)		(1,640	)		—
Total (benefit from) provision for income taxes	$	(1,825	)	$	5,696		$	1,044

The Company has incurred net operating losses since inception. The Company has not reflected any benefit of such net operating loss carryforwards in the accompanying financial statements. The Company has established a full valuation allowance against its deferred tax assets due to the uncertainty surrounding the realization of such assets.

Beginning in 2022, the Tax Cuts and Jobs Act of 2017 eliminated the right to deduct research and development expenditures for tax purposes in the period the expenses were incurred and instead requires all U.S. and foreign research and development expenditures to be amortized over five and fifteen tax years, respectively. Due to this required capitalization of research and development expenditures and the significant taxable income generated as a result of our sale of royalties in July 2022, the Company has recorded current state income tax expense of $6.1 million for the year ended December 31, 2022. For the year ended December 31, 2023, the Company recognized an income tax benefit of $4.8 million attributable to modifications in its state apportionment methodology. The Company realized no benefit for current year losses due to a full valuation allowance against the U.S. net deferred tax assets. The benefit was offset by an income tax expense of $3.0 million from foreign jurisdictions.

The effective tax rate of our provision for income taxes differs from the federal statutory rate as follows:


	Year Ended December 31,
	2023				2022				2021
Federal statutory income tax rate		21.0		%		21.0		%		21.0		%
State income taxes, net of federal benefit		0.8				(0.4	)			—
Federal tax credits		7.3				5.9				7.2
Other		(0.7	)			(0.1	)			0.5
Nondeductible permanent items		(0.3	)			(0.6	)			(0.8	)
Stock-based compensation		(1.8	)			(1.2	)			1.3
Uncertain tax positions		(1.4	)			(1.2	)			(1.4	)
Change in valuation allowance		(24.1	)			(24.0	)			(27.9	)
Foreign rate differential		(0.5	)			(0.2	)			(0.1	)
Provision for income taxes		0.3		%		(0.8	)	%		(0.2	)	%

The tax effect of temporary differences that give rise to significant portions of the deferred tax assets is presented below (in thousands):


	Year Ended December 31,
	2023			2022
Deferred tax assets:
Loss carryforwards	$	266,253		$	231,835
Tax credits		305,198			260,546
Stock options		44,795			39,784
Accruals and reserves		27,694			27,029
Fixed assets and intangibles		33,853			39,233
Liabilities for sales of future royalties		205,400			214,900
Basis difference in equity investments		8,423			8,971
Capitalized research and development costs		149,898			75,335
Other		281			3,028
Gross deferred tax assets		1,041,795			900,661
Valuation allowance		(1,035,836	)		(894,518	)
Total deferred tax assets		5,959			6,143
Deferred tax liabilities:
In-process research and development		(30,688	)		(31,667	)
Right-of-use lease assets		(5,329	)		(6,143	)
Gross deferred tax liabilities		(36,017	)		(37,810	)
Net deferred tax liabilities	$	(30,058	)	$	(31,667	)

As of December 31, 2023 and 2022, the Company had approximately $1,004.8 million and $756.6 million, respectively, of federal net operating loss carryforwards available to reduce future taxable income that will begin to expire in 2031. As of December 31, 2023 and 2022, the Company had approximately $659.9 million and $710.0 million, respectively, of state net operating loss carryforwards available to reduce future taxable income that will begin to expire in 2031.

As of December 31, 2023 and 2022, the Company had federal research tax credit carryforwards of approximately $46.9 million and $32.6 million, respectively, available to reduce future tax liabilities that will begin to expire in 2030. As of December 31, 2023 and 2022, the Company had state research credit carryforwards of $74.4 million and $59.9 million, respectively, available to reduce future tax liabilities that will be carried forward indefinitely.

As of December 31, 2023 and 2022, the Company had federal Orphan Drug Credits of $269.6 million and $239.3 million, respectively, available to reduce future tax liabilities that will begin to expire in 2031.

The Company’s ability to use net operating loss and tax credit carryforwards to reduce future taxable income and liabilities may be subject to annual limitations pursuant to Internal Revenue Code Sections 382 and 383 as a result of ownership changes in the past and future. As a result of ownership changes in 2012 and 2011, $3.6 million of federal net operating loss carryforwards, $3.6 million of state net operating loss carryforwards, and $0.2 million of federal tax credits are permanently limited. Deferred tax assets for net operating losses and tax credits have been reduced and a corresponding adjustment to the valuation allowance has been recorded.

The valuation allowance increased by $141.3 million and $193.8 million during the years ended December 31, 2023 and 2022, respectively.

Due to a change in the state tax rates, the Company recorded a net decrease to the deferred tax liability of $1.6 million with a corresponding deferred income tax benefit of $1.6 million for the year ended December 31, 2023.

The Company recorded unrecognized tax benefits for uncertainties in income taxes. A reconciliation of the Company’s unrecognized tax benefits follows (in thousands):


	December 31,
	2023		2022			2021
Balance at beginning of year	$	66,794	$	55,360		$	46,662
Additions based on tax positions related to current year		12,562		11,316			8,542
Additions for tax positions of prior years		642		377			356
Reductions for tax positions of prior years		—		(259	)		(200	)
Balance at end of year	$	79,998	$	66,794		$	55,360

Approximately $1.3 million in unrecognized tax benefits would impact the Company’s effective tax rate if recognized. The Company has elected to include interest and penalties as a component of tax expense. For the year ended December 31, 2023, the Company recognized accrued interest and penalties of $0.2 million as a component of income tax expense. No accrued interest and penalties were recognized as a component of income tax expense during the years ended December 31, 2022 and 2021. The Company does not anticipate that the amount of existing unrecognized tax benefits will significantly increase or decrease during the next year.

It is the Company’s intention to reinvest the earnings of its non-U.S. subsidiaries in their operations. As of December 31, 2023, the Company had not made a provision for any incremental foreign withholding taxes on approximately $10.8 million of the excess of the amount of net income for financial reporting over the tax basis of investments in foreign subsidiaries that are essentially permanent in duration. If these earnings were repatriated to the U.S., the deferred tax liability associated with these temporary differences would result in a nominal amount of withholding taxes.

The Company files income tax returns in the U.S. federal, 40 state tax jurisdictions, and ten foreign countries. The federal and state income tax returns from inception to December 31, 2023 remain subject to examination.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//740/tableOfContent

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-14

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-21

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 270
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482526/740-270-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 17
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-17

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.5.Q1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479360/740-10-S99-2

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482603/740-30-50-2

+ Details

License and Research Agreements - Schedule of Collaboration Cost Sharing and Payments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cost Sharing Payments [Line Items]
Cost of sales	$ 45,209	$ 28,320	$ 16,008
Kyowa Kirin Collaboration
Cost Sharing Payments [Line Items]
Research and development	(6,510)	(15,974)	(21,657)
Selling, general and administrative	(17,199)	(37,217)	(32,629)
Cost of sales	$ 18,476	$ 13,250	$ 6,701

GeneTx Acquisition

12 Months Ended

Dec. 31, 2023

Business Combinations [Abstract]

Acquisition

GeneTx Acquisition

In August 2019, the Company entered into a Program Agreement and a Unitholder Option Agreement with GeneTx Biotherapeutics LLC, or GeneTx, to collaborate on the development of GeneTx’s GTX-102, an ASO for the treatment of Angelman syndrome. In July 2022, pursuant to the terms of the Unitholder Option Agreement, as amended, the Company exercised the option to acquire GeneTx and entered into a Unit Purchase Agreement, or the Purchase Agreement, pursuant to which the Company purchased all the outstanding units of GeneTx. In accordance with the terms of the Purchase Agreement, the Company paid the option exercise price of $75.0 million and an additional $15.6 million to acquire the outstanding cash of GeneTx, and adjustments for working capital and transaction expenses of $0.6 million, for a total purchase consideration of $91.2 million. The Company may be required to make payments of up to $190.0 million upon the achievement of certain milestones, including up to $30.0 million in milestone payments upon achievement of the earlier of initiation of a Phase 3 clinical study or product approvals in Canada and the U.K., up to $85.0 million in additional regulatory approval milestones for the achievement of U.S. and EU product approvals, and up to $75.0 million in commercial milestone payments based on annual worldwide net product sales. The Company will also pay tiered mid- to high single-digit percentage royalties based on licensed product annual net sales. If the Company receives and resells an FDA priority review voucher, or PRV, in connection with a new drug application approval, GeneTx is entitled to receive a portion of proceeds from the sale or a cash payment from the Company if the Company choses to retain the PRV. As part of the Company's acquisition of GeneTx, the Company assumed a License Agreement with Texas A&M University, or TAMU. Under this agreement, TAMU is eligible to receive from the Company up to $23.5 million upon the achievement of various future milestones, a nominal annual license fee that may increase up to a maximum of $2.0 million, as well as royalties in the mid-single-digits of net sales.

The transaction was accounted as an asset acquisition, as substantially all of the fair value of the gross assets acquired was concentrated in a single identifiable in-process research and development intangible asset. Prior to the achievement of certain development and regulatory milestones, the acquired in-process research and development intangible asset has not yet reached technological feasibility and has no alternative future use. Accordingly, the Company recorded the acquisition price of $75.0 million, net of cash and working capital acquired, as in-process research and development expense during the year ended December 31, 2022.

Stock-Based Awards - Fair Value of Stock Option Awards Granted Estimated Using Black-Scholes Option-Pricing Model (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term in years	6 years 25 days	6 years 25 days	6 years 21 days
Expected volatility	55.00%	56.00%	60.00%
Risk-free interest rate	4.20%	2.00%	1.00%
Expected dividend rate	0.00%	0.00%	0.00%
Granted [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term in years		3 years 7 months 6 days
Expected volatility		57.00%
Risk-free interest rate		1.50%
Expected dividend rate		0.00%

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 1D
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480483/718-10-35-1D

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480483/718-10-35-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Accumulated Other Comprehensive Income (Loss) (Tables)

12 Months Ended

Dec. 31, 2023

Other Comprehensive Income (Loss), Net of Tax [Abstract]

Schedule of Total Accumulated Other Comprehensive Income (Loss)

Total accumulated other comprehensive income (loss) consisted of the following (in thousands):


	Year Ended December 31,
	2023			2022
Cumulative foreign currency translation adjustment	$	(606	)	$	(845	)
Unrealized gain (loss) on securities available-for-sale		1,253			(5,728	)
Total accumulated other comprehensive income (loss)	$	647		$	(6,573	)

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Treasury Stock	Deferred Compensation Obligation
Beginning balance at Dec. 31, 2020	$ 1,154,375	$ 67	$ 2,773,195	$ 689	$ (1,619,576)
Beginning balance, shares at Dec. 31, 2020		66,818,520
Issuance of common stock in connection with at-the-market offering, net of issuance costs	78,943	$ 1	78,942
Issuance of common stock in connection with at-the-market offering, net of issuance costs, shares		1,050,372
Stock-based compensation	105,260		105,260
Issuance of common stock under equity plan awards, net of tax	40,101	$ 1	40,100
Issuance of common stock under equity plan awards, net of tax, shares		1,476,106
Other comprehensive income (loss)	(2,093)			(2,093)
Net loss	(454,025)				(454,025)
Ending balance at Dec. 31, 2021	922,561	$ 69	2,997,497	(1,404)	(2,073,601)
Ending balance, shares at Dec. 31, 2021		69,344,998
Stock-based compensation	131,710		131,710
Issuance of common stock under equity plan awards, net of tax	10,813	$ 1	10,812
Issuance of common stock under equity plan awards, net of tax, shares		852,299
Other comprehensive income (loss)	(5,169)			(5,169)
Net loss	(707,421)				(707,421)
Ending balance at Dec. 31, 2022	$ 352,494	$ 70	3,140,019	(6,573)	(2,781,022)
Ending balance, shares at Dec. 31, 2022	70,197,297	70,197,297
Issuance of common stock and pre-funded warrants in connection with underwritten public offering, net of issuance costs	$ 326,456	$ 10	326,446
Issuance of common stock in connection with at-the-market offering, net of issuance costs	$ 53,299	$ 1	53,298
Issuance of common stock and pre-funded warrants in connection with underwritten public offering, net of issuance costs,shares		9,833,334
Issuance of common stock in connection with at-the-market offering, net of issuance costs, shares	1,175,584	1,175,584
Stock-based compensation	$ 134,169		134,169
Issuance of common stock upon exercise of warrants and under equity plan awards, net of tax	8,415	$ 1	8,414
Issuance of common stock upon exercise of warrants and under equity plan awards, net of tax, shares		1,109,375
Deferred compensation						$ (432)	$ 432
Other comprehensive income (loss)	7,220			7,220
Net loss	(606,639)				(606,639)
Ending balance at Dec. 31, 2023	$ 275,414	$ 82	$ 3,662,346	$ 647	$ (3,387,661)	$ (432)	$ 432
Ending balance, shares at Dec. 31, 2023	82,315,590	82,315,590

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
Net loss	$ (606,639)	$ (707,421)	$ (454,025)
Other comprehensive income (loss):
Foreign currency translation adjustments	239	(724)	(550)
Unrealized gain (loss) on available-for-sale securities	6,981	(4,445)	(1,543)
Other comprehensive income (loss):	7,220	(5,169)	(2,093)
Total comprehensive loss	$ (599,419)	$ (712,590)	$ (456,118)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

+ Details

- Definition

Amount after tax and reclassification adjustments of other comprehensive income (loss).

+ References

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+ Details

Intangible Assets, Net - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Finite Lived Intangible Assets Line Items
upfront payment	$ 30.0
Acquired Finite Lived Intangible Assets Weighted Average Useful Life		10 years
Regulatory milestone payments achieved		$ 10.0
Cost of sales
Finite Lived Intangible Assets Line Items
Costs of sales related to amortization of intangible asset		$ 3.8	$ 3.2	$ 0.3
Dimension
Finite Lived Intangible Assets Line Items
Intangible assets, remaining amortization period		5 years 8 months 12 days
Regulatory milestone payments achieved		$ 4.8

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	25,000,000	25,000,000
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares outstanding	82,315,590	70,197,297
Treasury stock , shares	9,559	0

Balance Sheet Components

12 Months Ended

Dec. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Balance Sheet Components

Cash Equivalents and Marketable Debt Securities

The fair values of cash equivalents and marketable debt securities classified as available-for-sale securities consisted of the following (in thousands):


	December 31, 2023
			Gross Unrealized
	Amortized Cost		Gains		Losses			Estimated Fair Value
Money market funds	$	162,289	$	—	$	—		$	162,289
Certificates of deposit and time deposits		17,986		—		—			17,986
Corporate bonds		214,792		711		(337	)		215,166
Commercial paper		20,620		—		—			20,620
Asset-backed securities		2,715		—		(3	)		2,712
U.S. Government Treasury and agency securities		316,160		982		(100	)		317,042
Total	$	734,562	$	1,693	$	(440	)	$	735,815


	December 31, 2022
			Gross Unrealized
	Amortized Cost		Gains		Losses			Estimated Fair Value
Money market funds	$	102,847	$	—	$	—		$	102,847
Certificates of deposit and time deposits		25,972		—		—			25,972
Corporate bonds		432,211		87		(4,700	)		427,598
Commercial paper		135,393		—		—			135,393
Asset-backed securities		12,002		—		(22	)		11,980
U.S. Government Treasury and agency securities		157,933		320		(1,263	)		156,990
Debt securities in government-sponsored entities		16,005		—		(150	)		15,855
Total	$	882,363	$	407	$	(6,135	)	$	876,635

At December 31, 2023, the remaining contractual maturities of available-for-sale securities were less than three years. There have been no significant realized gains or losses on available-for-sale securities for the periods presented.

Inventory

Inventory consists of the following (in thousands):


	December 31,
	2023		2022
Work-in-process	$	18,859	$	17,486
Finished goods		15,110		9,280
Total inventory	$	33,969	$	26,766

Property, Plant, and Equipment, net

Property, plant, and equipment, net consists of the following (in thousands):


		December 31,
	Useful life (years)	2023			2022
Building	20-30	$	181,356		$	2,798
Leasehold improvements	Shorter of lease term or estimated useful life		58,683			43,941
Research and development equipment	5		56,347			50,291
Furniture and office equipment	5		6,419			5,540
Computer equipment and software	3-5		16,196			13,876
Manufacturing equipment	5-15		37,297			570
Land	Not applicable		16,619			16,619
Construction-in-progress	Not applicable		867			189,448
Other	Varies by asset		183			24
Property, plant, and equipment, gross			373,967			323,107
Less: accumulated depreciation			(83,401	)		(63,381	)
Property, plant, and equipment, net		$	290,566		$	259,726

Depreciation expense for the years ended December 31, 2023, 2022, and 2021 was $22.2 million, $15.0 million and $12.9 million, respectively. Amortization of leasehold improvements and software is included in depreciation expense.

Construction in progress reflects amounts incurred for construction or improvements of property or costs for equipment that has not been placed in service. The construction-in-progress balance as of December 31, 2022 is primarily the construction costs for the gene therapy manufacturing facility in Bedford, Massachusetts.

Accrued Liabilities

Accrued liabilities consists of the following (in thousands):


	December 31,
	2023		2022
Research, clinical study, and manufacturing expenses	$	65,326	$	73,558
Payroll and related expenses		82,936		78,938
Other		48,224		52,182
Total accrued liabilities	$	196,486	$	204,678

Stock-Based Awards

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Stock-Based Awards

12.

Stock-Based Awards

Equity Plan Awards

In 2014, the Company adopted the 2014 Incentive Plan, or the 2014 Plan, for the granting of stock-based awards to employees, directors, and consultants under terms and provisions established by the board of directors. The 2014 Plan had 2,250,000 shares of common stock available for future issuance at the time of its inception. The 2014 Plan provided for automatic annual increases in shares available for grant, beginning on January 1, 2015 through June 7, 2023. In June 2023, the Company adopted the 2023 Incentive Plan which had 4,500,000 shares of common stock available for future issuance at the time of its inception, plus the number of shares subject to the 2014 Plan cancelled after June 7, 2023. No further shares were granted under the 2014 Plan after June 7, 2023.In February 2021, the Company adopted the Employment Inducement Plan, or the Inducement Plan, which was subsequently amended in June 2023 to provide for a maximum of 850,000 shares available for grant under the plan. In 2014, the Company adopted the 2014 Incentive Plan, or the 2014 Plan, for the granting of stock-based awards to employees, directors, and consultants under terms and provisions established by the board of directors. Under the terms of the 2023 Plan and Inducement Plan, awards may be granted at an exercise price not less than fair market value. The exercise price of an option may not be less than the fair market value. The term of an award granted under the 2023 Plan and Inducement Plan may not exceed ten years. Typically, the vesting schedule for option grants to the employees provides that ¼ of the grant vests upon the first anniversary of the date of grant, with the remainder of the shares vesting monthly thereafter at a rate of 1/48 of the total shares subject to the option. Typically, the vesting schedule for RSU grants provides that ¼ of the grant vests upon the annual anniversary of the date of grant over the period of four years.

As of December 31, 2023, an aggregate of 19,610,125 shares of common stock have been authorized for issuance under the 2014 Plan, the 2023 Plan, and the Inducement Plan.

Stock Option Activity

The following table summarizes activity under the Company’s stock option plans and related information:


	Options Outstanding
	Number of Options			Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value
							(In thousands)
Outstanding — December 31, 2022		7,773,367		$	72.56	6.60	$	8,476
Options granted		2,123,256			45.05
Options exercised		(209,793	)		13.07
Options cancelled		(899,118	)		71.56
Outstanding — December 31, 2023		8,787,712			67.43	6.39		7,558
Vested and exercisable — December 31, 2023		5,415,110			73.28	4.96		1,214
Vested and expected to vest — December 31, 2023		8,461,973			67.96	6.29		6,794

The aggregate intrinsic values of options outstanding, vested and exercisable, and vested and expected to vest were calculated as the difference between the exercise price of the options and the fair value of the Company’s common stock. The total intrinsic value of options exercised during the years ended December 31, 2023, 2022, and 2021 was $4.9 million, $2.6 million, and $38.8 million, respectively. Cash received from the exercise of options was $2.7 million, $6.2 million, and $36.6 million for the years ended December 31, 2023, 2022, and 2021, respectively.

The weighted-average estimated fair value of stock options granted was $25.53, $34.77, and $70.84 per share of the Company’s common stock during the years ended December 31, 2023, 2022, and 2021, respectively. The total estimated grant date fair value of options vested during the years ended December 31, 2023, 2022, and 2021 was $59.7 million, $58.7 million, and $48.1 million, respectively.

Performance Stock Options

The following table summarizes activity under the Company’s Performance Stock Option, or PSO, plans and related information:


	PSOs Outstanding
	Number of Options			Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value
Outstanding — December 31, 2022		1,624,599		$	67.37		4.14	$	—
PSOs cancelled		(243,601	)		67.37
Outstanding — December 31, 2023		1,380,998			67.37		3.15		—
Vested and exercisable — December 31, 2023		117,865			67.37		3.09		—
Vested and expected to vest — December 31, 2023		983,173			67.37		3.14		—

During the year ended December 31, 2022, PSOs were granted to certain nonexecutive employees. PSOs are subject to vest only if specified operational milestones are achieved and the employees’ continued service with the Company. The Company uses the Black-Scholes method to calculate the fair value at the grant date and is recognizing stock-based compensation expense for the PSOs that are expected to vest. Stock-based compensation for PSOs is recognized over the service period, beginning in the period the Company determines it is probable that a milestone will be achieved. Forfeitures of PSOs are recognized as they occur. The Company reassesses the probability of the performance condition at each reporting period and adjusts the compensation cost based on the probability assessment. As of December 31, 2023, certain operational milestones were deemed probable of achievement. The aggregate intrinsic values of PSOs outstanding, vested and exercisable, and vested and expected to vest were calculated as the difference between the exercise price of the PSOs and the fair value of the Company’s common stock. The total estimated grant date fair value of PSOs vested during the year ended December 31, 2023, was $3.4 million. No PSOs were granted or were exercised during the year ended December 31, 2023. The weighted-average estimated fair value of PSOs granted was $28.76 during the year ended December 31, 2022.

Restricted Stock Units

The following table summarizes activity under the Company’s Restricted Stock Units, or RSU, plans and related information:


	RSUs Outstanding
	Number of Shares			Weighted- Average Grant Date Fair Value
Unvested — December 31, 2022		2,129,153		$	75.11
RSUs granted		2,447,170			44.52
RSUs vested		(738,130	)		73.99
RSUs cancelled		(394,081	)		61.22
Unvested — December 31, 2023		3,444,112			55.21

The fair value of the RSUs is determined on the grant date based on the fair value of the Company’s common stock. The fair value of the RSUs is recognized as expense ratably over the vesting period of one to four years. The total grant date fair value of the RSUs vested during the years ended December 31, 2023, 2022, and 2021 was $54.6 million, $47.1 million, and $35.5 million, respectively. The aggregate intrinsic value of the shares of the RSUs vested during the years ended December 31, 2023, 2022, and 2021 was $33.0 million, $37.8 million, and $69.9 million, respectively.

Performance Stock Units

The following table summarizes activity under the Company’s Performance Stock Units, or PSUs and related information:


	PSUs Outstanding
	Number of Shares			Weighted- Average Grant Date Fair Value
Unvested — December 31, 2022		209,230		$	98.09
PSUs granted		362,470			50.29
PSUs vested		(27,581	)		141.86
PSUs cancelled		(38,013	)		106.80
Unvested — December 31, 2023		506,106			60.82

The fair value of the PSUs is determined on the grant date based on the fair value of the Company’s common stock, except for certain PSUs with a market vesting condition, for which fair value is estimated using a Monte Carlo simulation model. PSUs are subject to vest only if certain specified criteria are achieved and the employees’ continued service with the Company. For certain PSUs, the number of PSUs that may vest are also subject to the achievement of certain specified criteria, including both performance conditions and market conditions. As of December 31, 2023, certain specified criteria were deemed probable of achievement or already achieved. Stock-based compensation for PSUs is recognized over the service period beginning in the period the Company determines it is probable that the performance criteria will be achieved. The total grant date fair value of the PSUs vested during the years ended December 31, 2023, 2022, and 2021 was $3.9 million, $1.6 million, and $9.2 million, respectively, with an aggregate intrinsic value of the shares of $1.3 million, $2.0 million and $18.9 million, respectively.

Employee Stock Purchase Plan

In January 2014, the Company adopted the 2014 Employee Stock Purchase Plan, or ESPP, which was amended and restated in June 2023. Under the ESPP, eligible employees may purchase common stock at 85% of the lesser of the fair market value of common stock on the offering date or the purchase date with a six-month look-back feature. ESPP purchases are settled with common stock from the ESPP’s previously authorized and available pool of shares. During the year ended December 31, 2023, the Company issued 195,462 shares of common stock under the ESPP. As of December 31, 2023, an aggregate of 6,609,795 shares of common stock have been authorized for future issuance on the ESPP.

Stock-Based Compensation Expense

Total stock-based compensation recognized was as follows (in thousands):


	Year Ended December 31,
	2023		2022		2021
Cost of sales	$	1,166	$	902	$	871
Research and development		74,531		74,464		59,097
Selling, general and administrative		59,516		55,002		45,011
Total stock-based compensation expense	$	135,213	$	130,368	$	104,979

Stock-based compensation of $1.9 million, $2.2 million, and $1.7 million was capitalized into inventory for the years ended December 31, 2023, 2022, and 2021, respectively. Capitalized stock-based compensation is recognized as cost of sales when the related product is sold. As of December 31, 2023, the total unrecognized compensation expense related to unvested equity awards, net of estimated forfeitures, was $219.8 million, which the Company expects to recognize over an estimated weighted-average period of 2.2 years. In determining the estimated fair value of the stock options, PSOs and ESPP, the Company uses the Black-Scholes option-pricing model and assumptions discussed below. Each of these inputs is subjective and generally requires significant judgment to determine.

Expected Term—The Company’s expected term represents the period that the Company’s stock-based awards are expected to be outstanding and is determined using the simplified method (based on the mid-point between the vesting date and the end of the contractual term).

Expected Volatility—The Company’s expected volatility is based on historical volatility over the look-back period corresponding to the expected term.

Risk-Free Interest Rate—The risk-free interest rate is based on the U.S. Treasury zero coupon issues in effect at the time of grant for periods corresponding with the expected term of option.

Expected Dividend—The Company has never paid dividends on its common stock and has no plans to pay dividends on its common stock. Therefore, the Company used an expected dividend yield of zero.

Strike price for options awards and PSOs is equal to the closing market value of our common stock on the date of grant.

The fair value of stock option awards granted was estimated at the date of grant using a Black-Scholes option-pricing model with the following weighted-average assumptions:


	Year Ended December 31,
	2023	2022	2021
Expected term (years)	6.07	6.07	6.06
Expected volatility	55%	56%	60%
Risk-free interest rate	4.2%	2.0%	1.0%
Expected dividend rate	0.0%	0.0%	0.0%

The fair value of PSOs granted was estimated at the date of grant using a Black-Scholes option-pricing model with the following weighted-average assumptions:


		Year Ended December 31,
		2022
Expected term in years		3.60
Expected volatility		57%
Risk-free interest rate		1.5%
Expected dividend rate		0.0%

License and Research Agreements - REGENXBIO, Inc. - Additional Information (Details) - REGENXBIO, Inc. - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2023
Option and License Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Future contingent milestone payments		$ 9.0
Option and license agreement description		The Company also has an option and license agreement with REGENX under which the Company has an exclusive, sublicensable, worldwide license to make, have made, use, import, sell, and offer for sale licensed products to treat Wilson disease and CDKL5 deficiency.
Annual maintenance fee for each option exercised		$ 0.1
License Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Future contingent milestone payments		14.0
Upfront payment for in-process research and development expense	$ 7.0
Annual fees payable		$ 0.1

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
Document and Entity Information - USD ($) $ in Billions	Dec. 31, 2023	Feb. 15, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Trading Symbol	RARE
Entity Registrant Name	Ultragenyx Pharmaceutical Inc.
Entity Central Index Key	0001515673
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		82,335,687
Entity Public Float			$ 3.1
Security Exchange Name	NASDAQ
Title of 12(b) Security	Common Stock, $0.001 par value
Entity File Number	001-36276
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	27-2546083
Entity Address, Address Line One	60 Leveroni Court
Entity Address, City or Town	Novato
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94949
City Area Code	415
Local Phone Number	483-8800
Document Annual Report	true
Document Transition Report	false
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant’s definitive proxy statement relating to its 2024 Annual Meeting of Stockholders, to be held on or about June 18, 2024, are incorporated by reference into Part III of this Annual Report on Form 10-K where indicated. Such proxy statement will be filed with the U.S. Securities and Exchange Commission within 120 days after the end of the fiscal year to which this report relates.
Auditor Firm ID	42
Auditor Name	Ernst & Young LLP
Auditor Location	San Mateo, California

Commitments and Contingencies - Summary of Aggregate Payments under Contractually Binding Manufacturing and Service Agreements (Details) - Manufacturing and Services $ in Thousands	Dec. 31, 2023 USD ($)
Commitments And Contingencies Disclosure Line Items
2024	$ 27,899
2025	5,718
Contractual Obligation, Total	$ 33,617

GeneTx Acquisition - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jul. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Business Acquisition [Line Items]
Acquired in-process research and development		$ 0	$ 75,033	$ 0
GeneTx [Member]
Business Acquisition [Line Items]
Business acquisition, consideration transferred	$ 75,000
Regulatory Approval Milestones	85,000
Outstanding Cash and Cash Equivalents Acquired	15,600
Amount on adjustments for working capital and transaction expenses	600
Payments to Acquire Businesses, Gross	91,200
GeneTx [Member] \| Maximum
Business Acquisition [Line Items]
Future contingent milestone payments	190,000
Additional Milestone Payments	30,000
Commercial Milestone Payment	75,000
Texas A&M University [Member] \| Maximum
Business Acquisition [Line Items]
Future contingent milestone payments	23,500
Annual License Fee Payment	$ 2,000
In-process Research and Development [Member] \| GeneTx [Member]
Business Acquisition [Line Items]
Acquired in-process research and development			$ 75,000

License and Research Agreements - Arcturus Therapeutics Holdings Inc. - Additional Information (Details) $ / shares in Units, $ in Millions	1 Months Ended			12 Months Ended
	May 31, 2020 USD ($) shares	Jun. 30, 2019 USD ($) DiseaseTarget $ / shares shares	Oct. 31, 2015 USD ($)	Dec. 31, 2022 $ / shares shares	Dec. 31, 2021 USD ($)	Dec. 31, 2023 $ / shares
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Common stock. per share \| $ / shares				$ 0.001		$ 0.001
Arcturus Therapeutics Holdings Inc
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone payments received					$ 1.0
Upfornt cash payment paid		$ 6.0
Common stock purchased \| shares		2,400,000
Common stock shares sold \| shares				500,000
Common stock. per share \| $ / shares		$ 10		$ 20.39
Business acquisition, consideration transferred		$ 30.0
Additional option to purchase common stock \| shares		600,000
Additional option to purchase common stock value per share \| $ / shares		$ 16
Number of shares purchased on exercise of common stock option \| shares	600,000
Purchase price of shares purchased on exercise of common stock option	$ 9.6
Number of common stock held \| shares				0
Arcturus Therapeutics Holdings Inc \| Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of disease targets \| DiseaseTarget		12
Regulatory milestone payments			$ 24.5
Commercial milestone payments			$ 45.0

Summary of Significant Accounting Policies - Summary of Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Cash and cash equivalents	$ 213,584	$ 132,944	$ 307,584
Restricted cash included in other current assets	$ 2,008	$ 862	$ 0
Restricted Cash and Cash Equivalents, Current, Asset, Statement of Financial Position [Extensible List]	Other assets	Other assets	Other assets
Restricted cash included in other non-current assets	$ 3,807	$ 3,795	$ 2,001
Restricted Cash and Cash Equivalents, Noncurrent, Asset, Statement of Financial Position [Extensible List]	Other assets	Other assets	Other assets
Total cash, cash equivalents, and restricted cash shown in the statements of cash flows	$ 219,399	$ 137,601	$ 309,585	$ 726,294

Leases - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Lessee Disclosure [Abstract]
Operating lease extension details	multiple renewal periods
Operating lease, existence of option to extend	true
Operating lease expiry term	2029
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Other Assets, Noncurrent	Other Assets, Noncurrent
Right-of-use lease assets	$ 23.9	$ 26.0
Cash paid for measurement of operating lease liabilities	$ 13.4	$ 13.1	$ 11.8
Operating lease weighted average remaining lease term	4 years 6 months	3 years
Financing lease weighted average remaining lease term		2 years 9 months 18 days
Operating lease weighted average discount rate	9.60%	6.70%
Financing lease weighted average discount rate		5.10%

Stock-Based Awards - Summary of Activity Under Restricted Stock Units (RSUs) from 2014 Plan (Details) - Restricted Stock Units	12 Months Ended
	Dec. 31, 2023 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding, Number of Shares, Unvested, Beginning Balance \| shares	2,129,153
Number of shares, granted \| shares	2,447,170
Number of shares, vested \| shares	(738,130)
Number of shares, cancelled \| shares	(394,081)
Outstanding, Number of Shares, Unvested, Ending Balance \| shares	3,444,112
Outstanding, Weighted-Average Grant Date Fair Value, Unvested, Beginning Balance \| $ / shares	$ 75.11
Weighted-Average Grant Date Fair Value, granted \| $ / shares	44.52
Weighted-Average Grant Date Fair Value, vested \| $ / shares	73.99
Weighted-Average Grant Date Fair Value, cancelled \| $ / shares	61.22
Weighted- Average Exercise Price,Outstanding December 31, 2023 \| $ / shares	$ 55.21

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

Summary of Financial Assets Measured on Recurring Basis

The following tables set forth the fair value of the Company’s financial assets remeasured on a recurring basis based on the three-tier fair value hierarchy (in thousands):


	December 31, 2023
	Level 1		Level 2		Level 3		Total
Financial Assets:
Money market funds	$	162,289	$	—	$	—	$	162,289
Certificates of deposit and time deposits		—		17,986		—		17,986
Corporate bonds		—		215,166		—		215,166
Commercial paper		—		20,620		—		20,620
Asset-backed securities		—		2,712		—		2,712
U.S. Government Treasury and agency securities		57,437		259,605		—		317,042
Investment in Solid common stock		3,204		—		—		3,204
Deferred compensation assets		—		10,220		—		10,220
Total financial assets	$	222,930	$	526,309	$	—	$	749,239

Financial Liabilities:
Deferred compensation liabilities	$	—	$	10,365	$	—	$	10,365


	December 31, 2022
	Level 1		Level 2		Level 3		Total
Financial Assets:
Money market funds	$	102,847	$	—	$	—	$	102,847
Certificates of deposit and time deposits		—		25,972		—		25,972
Corporate bonds		—		427,598		—		427,598
Commercial paper		—		135,393		—		135,393
Asset-backed securities		—		11,980		—		11,980
U.S. Government Treasury and agency securities		27,645		129,345		—		156,990
Debt securities in government-sponsored entities		—		15,855		—		15,855
Investment in Solid common stock		2,807		—		—		2,807
Deferred compensation assets		—		4,575		—		4,575
Total financial assets	$	133,299	$	750,718	$	—	$	884,017

Financial Liabilities:
Deferred compensation liabilities	$	—	$	4,657	$	—	$	4,657

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2023

Commitments and Contingencies Disclosure [Abstract]

Summary of Aggregate Payments under Contractually Binding Manufacturing and Service Agreements

As of December 31, 2023, the aggregate payments under contractually-binding manufacturing and service agreements are as follows (in thousands):


	Year Ended December 31,
	2024		2025		Total
Manufacturing and Services	$	27,899	$	5,718	$	33,617

Fair Value Measurements - Summary of Financial Assets Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	$ 749,239	$ 884,017
Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	222,930	133,299
Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	526,309	750,718
Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	162,289	102,847
Money Market Funds \| Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	162,289	102,847
Asset-backed Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	2,712	11,980
Asset-backed Securities \| Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	2,712	11,980
Certificates of Deposit and Time Deposits
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	17,986	25,972
Certificates of Deposit and Time Deposits \| Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	17,986	25,972
Corporate Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	215,166	427,598
Corporate Bonds \| Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	215,166	427,598
Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	20,620	135,393
Commercial Paper \| Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	20,620	135,393
U.S. Government Treasury and Agency Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	317,042	156,990
U.S. Government Treasury and Agency Securities \| Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	57,437	27,645
U.S. Government Treasury and Agency Securities \| Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	259,605	129,345
Debt Securities in Government Sponsored Entities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value		15,855
Debt Securities in Government Sponsored Entities \| Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value		15,855
Investments in Solid Common Stock
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	3,204	2,807
Investments in Solid Common Stock \| Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	3,204	2,807
Deferred compensation assets
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	10,220	4,575
Deferred compensation assets \| Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	10,220	4,575
Deferred compensation liabilities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	10,365	4,657
Deferred compensation liabilities \| Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total fair value	$ 10,365	$ 4,657

Net Loss per Share - Computation of Basic and Diluted Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Numerator:
Net loss	$ (606,639)	$ (707,421)	$ (454,025)
Denominator:
Weighted-average shares used to computing net loss per share, basic	73,543,862	69,914,225	67,795,540
Weighted-average shares used to computing net loss per share, diluted	73,543,862	69,914,225	67,795,540
Net loss per share, basic	$ (8.25)	$ (10.12)	$ (6.7)
Net loss per share, diluted	$ (8.25)	$ (10.12)	$ (6.7)

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ References

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+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

+ Details

License and Research Agreements (Tables)

12 Months Ended

Dec. 31, 2023

Share of Collaboration and Royalty Revenue Related to Crysvita

Total Crysvita revenue was as follows (in thousands):


	Year Ended December 31,
	2023		2022		2021
Revenue in profit-share territory:
Collaboration revenue	$	69,705	$	215,024	$	171,198
Royalty revenue		113,288		—		—
Non-cash royalty revenue		48,581		—		—
Total revenue in Profit-Share Territory		231,574		215,024		171,198
Product sales		75,697		42,678		21,422
Royalty revenue in European Territory		—		—		244
Non-cash royalty revenue in European Territories		20,783		21,692		17,951
Total Crysvita revenue	$	328,054	$	279,394	$	210,815

Royalty Revenue for Sales in the European Territory

KKC has the commercial responsibility for Crysvita in the European Territory. In December 2019, the Company sold its right to receive royalty payments based on sales in the European Territory to Royalty Pharma, effective January 1, 2020, as further described in Note 10. Prior to the Company’s sale of the royalty, the Company received a royalty of up to 10% on net sales in the European Territory, which was recognized as the underlying sales occur. Beginning in 2020, the Company records the royalty revenue as non-cash royalty revenues. The Company records this revenue as royalty revenue.

Schedule Of Collaboration Cost Sharing and Payments

These amounts were recognized in the Company’s Statements of Operations in connection with the collaboration agreement with KKC as follows (in thousands):


	Year Ended December 31,
	2023			2022			2021
Research and development	$	(6,510	)	$	(15,974	)	$	(21,657	)
Selling, general and administrative	$	(17,199	)	$	(37,217	)	$	(32,629	)
Cost of sales	$	18,476		$	13,250		$	6,701

Solid Biosciences, Inc.

Schedule of Changes in Fair Value of Investment in Securities

The changes in the fair value of the Company’s investment in Solid’s common stock were as follows (in thousands):


	Solid Common Stock
December 31, 2021	$	13,695
Change in fair value		(10,888	)
December 31, 2022		2,807
Change in fair value		397
December 31, 2023	$	3,204

Arcturus

Schedule of Changes in Fair Value of Equity Investment

The changes in the fair value of the Company’s equity investment in Arcturus were as follows (in thousands):


	Arcturus Common Stock
December 31, 2021	$	18,505
Change in fair value		(8,411	)
Sale of shares		(10,094	)
December 31, 2022	$	—

Balance Sheet Components - Summary of Cash Equivalents and Marketable Debt Securities Classified as Available For Sale Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 734,562	$ 882,363
Gross Unrealized Gains	1,693	407
Gross Unrealized Losses	(440)	(6,135)
Estimated Fair Value	735,815	876,635
Money Market Funds
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	162,289	102,847
Estimated Fair Value	162,289	102,847
Asset-backed Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	2,715	12,002
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(3)	(22)
Estimated Fair Value	2,712	11,980
Certificates of Deposit and Time Deposits
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	17,986	25,972
Estimated Fair Value	17,986	25,972
Corporate Bonds
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	214,792	432,211
Gross Unrealized Gains	711	87
Gross Unrealized Losses	(337)	(4,700)
Estimated Fair Value	215,166	427,598
Commercial Paper
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	20,620	135,393
Estimated Fair Value	20,620	135,393
U.S. Government Treasury and Agency Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	316,160	157,933
Gross Unrealized Gains	982	320
Gross Unrealized Losses	(100)	(1,263)
Estimated Fair Value	$ 317,042	156,990
Debt Securities in Government Sponsored Entities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost		16,005
Gross Unrealized Losses		(150)
Estimated Fair Value		$ 15,855

Revenue - Schedule of Sales-Related Accruals and Allowances (Details) - Product sales - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation Of Revenue [Line Items]
Balance of product sales reserve at beginning of year	$ 11,487	$ 7,181	$ 3,913
Provisions	18,761	13,525	9,586
Payments	(12,746)	(9,613)	(6,120)
Adjustments	(473)	394	(198)
Balance of product sales reserve at end of year	$ 17,029	$ 11,487	$ 7,181

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

License and Research Agreements

12 Months Ended

Dec. 31, 2023

Research Grant Agreement [Abstract]

License and Research Agreements

Kyowa Kirin Co., Ltd.

In August 2013, the Company entered into a collaboration and license agreement with Kyowa Kirin Co., Ltd., or KKC. Under the terms of this collaboration and license agreement, as amended, the Company and KKC collaborate on the development and commercialization of Crysvita in the field of orphan diseases in the U.S. and Canada, or the Profit-Share Territory, and in the European Union, United Kingdom, and Switzerland, or the European Territory, and the Company has the right to develop and commercialize such products in the field of orphan diseases in Mexico and Central and South America, or Latin America.

Development Activities

In the field of orphan diseases, except for ongoing studies being conducted by KKC, the Company was the lead party for development activities in the Profit-Share Territory and in the European Territory until the applicable transition date. The Company shared the costs for development activities in the Profit-Share Territory and the European Territory conducted pursuant to the development plan before the applicable transition date equally with KKC. In April 2023, which was the transition date for the Profit-Share Territory, KKC became the lead party and became responsible for the costs of the subsequent development activities. However, the Company will continue to equally share in the costs of the studies with KKC that commenced prior to the applicable transition date.

The collaboration and license agreements are within the scope of ASC 808, which provides guidance on the presentation and disclosure of collaborative arrangements.

Collaboration and Royalty Revenue for Sales in the Profit-Share Territory

The Company and KKC shared commercial responsibilities and profits in the Profit-Share Territory until April 2023. Under the collaboration agreement, KKC manufactured and supplied Crysvita for commercial use in the Profit-Share Territory and charged the Company a transfer price of 30% of net sales in 2023, and 35% prior to December 31, 2022. The remaining profit or loss after supply

costs from commercializing products in the Profit-Share Territory was shared between the Company and KKC on a 50/50 basis until April 2023. In April 2023, commercialization responsibilities for Crysvita in the Profit-Share Territory transitioned to KKC. Thereafter, the Company is entitled to receive a tiered double-digit revenue share from the mid-20% range up to a maximum rate of 30%.

In 2022, the Company entered into an amendment to the collaboration agreement which granted the Company the right to continue to support KKC in commercial field activities in the U.S. through April 2024, subject to the limitations and conditions set forth in the amendment. The parties subsequently mutually agreed to extend the Company's right to continue to support KKC in commercial field activities in the U.S. through December 31, 2024, and as a result, the Company will continue to support commercial field efforts in the U.S. through a cost share arrangement through December 2024. After December 31, 2024, the Company’s rights to promote Crysvita in the U.S. will be limited to medical geneticists and the Company will solely bear its expenses for the promotion of Crysvita in the Profit-Share Territory.

As KKC was the principal in the sale transaction with the customer during the profit-share period, the Company recognized a pro-rata share of collaboration revenue, net of transfer pricing, in the period the sale occurs. The Company concluded that its portion of KKC’s sales in the Profit-Share Territory prior to April 2023 was analogous to a royalty and therefore recorded its share as collaboration revenue, similar to a royalty. Starting in April 2023, the Company began to record the royalty revenue as the underlying sales occur.

In July 2022, the Company sold to OMERS its right to receive 30% of the future royalty payments due to the Company based on net sales of Crysvita in the U.S. and Canada, subject to a cap, beginning in April 2023, as further described in Note 10. The Company records this revenue as royalty revenue.

Product Sales Revenue for Other Territories

The Company is responsible for commercializing Crysvita in Latin America and Turkey. The Company is considered the principal in these territories as the Company controls the product before it is transferred to the customer. Accordingly, the Company records revenue on a gross basis for the sale of Crysvita once the product is delivered and the risk and title of the product is transferred to the distributor. KKC has the option to assume responsibility for commercialization efforts in Turkey from the Company, after a certain minimum period.

Under the collaboration agreement, KKC manufactures and supplies Crysvita, which is purchased by the Company for sales in Latin American territories and charges the Company a transfer price of 30% of net sales. The transfer price on these sales was 35% prior to December 31, 2022. The Company also pays to KKC a low single-digit royalty on net sales in Latin America.

Total Crysvita revenue was as follows (in thousands):


	Year Ended December 31,
	2023		2022		2021
Revenue in profit-share territory:
Collaboration revenue	$	69,705	$	215,024	$	171,198
Royalty revenue		113,288		—		—
Non-cash royalty revenue		48,581		—		—
Total revenue in Profit-Share Territory		231,574		215,024		171,198
Product sales		75,697		42,678		21,422
Royalty revenue in European Territory		—		—		244
Non-cash royalty revenue in European Territories		20,783		21,692		17,951
Total Crysvita revenue	$	328,054	$	279,394	$	210,815

Royalty Revenue for Sales in the European Territory

Collaboration Cost Sharing and Payments

Under the collaboration agreement, KKC and the Company share certain development and commercialization costs and as a result, the Company was reimbursed for these costs and operating expenses were reduced. Additionally, KKC is owed a transfer price fee and royalties on certain revenues and the Company recorded amounts owed to KKC in cost of sales. These amounts were recognized in the Company’s Statements of Operations in connection with the collaboration agreement with KKC as follows (in thousands):


	Year Ended December 31,
	2023			2022			2021
Research and development	$	(6,510	)	$	(15,974	)	$	(21,657	)
Selling, general and administrative	$	(17,199	)	$	(37,217	)	$	(32,629	)
Cost of sales	$	18,476		$	13,250		$	6,701

Collaboration Receivable and Payable

The Company had accounts receivable from KKC in the amount of $39.2 million and $27.5 million from profit-share revenue and royalties and other receivables recorded in other current assets of $1.1 million and $6.4 million and accrued liabilities of $5.3 million and $3.1 million from commercial and development activity reimbursements, as of December 31, 2023 and 2022, respectively.

Saint Louis University

In November 2010, the Company entered into a license agreement with Saint Louis University, or SLU. Under the terms of this license agreement, SLU granted the Company an exclusive worldwide license to make, have made, use, import, offer for sale, and sell therapeutics related to SLU’s beta-glucuronidase product for use in the treatment of human diseases.

The Company made a milestone payment of $0.1 million upon approval of Mepsevii for treatment of MPS 7. The Company is required to pay to SLU a low single-digit royalty on net sales of the licensed products in any country or region, upon reaching a certain level of cumulative worldwide sales of the product.

Baylor Research Institute

In September 2012, the Company entered into a license agreement with Baylor Research Institute, or BRI. Under the terms of this license agreement, as amended, BRI exclusively licensed to the Company its territories for certain intellectual property related to Dojolvi (triheptanoin) for the treatment of LC-FAOD.

For the years ended December 31, 2023 and 2022, the Company recorded nil and $2.5 million, respectively, for the attainment of various development and commercial milestones as finite-lived intangible assets. The Company is obligated to make additional future payments of up to $7.5 million contingent upon attainment of various development and commercial milestones. Additionally, the Company is paying BRI a mid- single-digit royalty on net sales of the licensed product in the licensed territories.

REGENXBIO, Inc.

The Company has a license agreement with REGENXBIO, Inc., or REGENX, for an exclusive, sublicensable, worldwide commercial license under certain intellectual property for preclinical and clinical research and development, and commercialization of drug therapies using REGENX's licensed patents for the treatment of hemophilia A, OTC deficiency, and GSD1a. The Company will pay an annual fee and certain milestone fees per disease indication, low to mid- single-digit royalty percentages on net sales of licensed products, and milestone and sublicense fees owed by REGENX to its licensors, contingent upon the attainment of certain development activities as outlined in the agreement.

The Company also has an option and license agreement with REGENX under which the Company has an exclusive, sublicensable, worldwide license to make, have made, use, import, sell, and offer for sale licensed products to treat Wilson disease and CDKL5 deficiency. For each disease indication, the Company is obligated to pay an annual maintenance fee of $0.1 million and up to $9.0 million upon achievement of various milestones, as well as mid- to high single-digit royalties on net sales of licensed products and mid- single-digit to low double-digit percentage sublicenses fees, if any.

In March 2020, the Company entered into a license agreement with REGENX, for an exclusive, sublicensable, worldwide license to REGENX’s NAV AAV8 and AAV9 vectors for the development and commercialization of gene therapy treatments for a rare metabolic disorder. In return for these rights, the Company made an upfront payment of $7.0 million. The Company will pay certain

annual fees of $0.1 million, milestone payments of up to $14.0 million, and royalties on any net sales of products incorporating the licensed intellectual property that range from a high single-digit to low double-digit royalty.

Bayer HealthCare LLC

The Company previously had a collaboration and license agreement with Bayer Healthcare LLC, or Bayer, to research, develop and commercialize AAV gene therapy products for the treatment of hemophilia A, or DTX 201. Under this agreement, Bayer had been granted an exclusive license to develop and commercialize one or more novel gene therapies for hemophilia A.

In October 2022, the Collaboration and License Agreement for DTX201 with Bayer was terminated and all licensed rights to DTX201 have reverted back to the Company. The Company also obtained rights to all necessary data and information to further develop DTX201 or another hemophilia A program through a royalty-free, worldwide, sublicensable, perpetual license.

University of Pennsylvania

The Company has a research, collaboration, and license agreement with University of Pennsylvania School of Medicine, or Penn, which provides the terms for the Company and Penn to collaborate with respect to the pre-clinical development of gene therapy products for the treatment of certain indications. Under the agreement, Penn granted the Company an exclusive, worldwide license to certain patent rights arising out of the research program, subject to certain retained rights, and a non-exclusive, worldwide license to certain Penn intellectual property, in each case to research, develop, make, have made, use, sell, offer for sale, commercialize and import licensed products in each indication for the term of the agreement. The Company will fund the cost of the research program in accordance with a mutually agreed-upon research budget and will be responsible for clinical development, manufacturing and commercialization of each indication. The Company may be obligated to make milestone payments of up to $5.0 million for each indication, if certain development milestones are achieved over time. The Company is also obligated to make milestone payments of up to $25.0 million per approved product if certain commercial milestones are achieved, as well as low to mid- single-digit royalties on net sales of each licensed product.

Arcturus Therapeutics Holdings Inc.

In October 2015, the Company entered into a Research Collaboration and License Agreement with Arcturus Therapeutics Holdings Inc., or Arcturus, to collaborate on the research and development of therapies for select rare diseases. Arcturus was responsible for conducting certain research services, funded by the Company, and the Company was responsible for development and commercialization costs.

On a product-by-product basis, the Company is obligated to make development and regulatory milestone payments of up to $24.5 million, and commercial milestone payments of up to $45.0 million if certain milestones are achieved. For the year ended December 31, 2021, the Company achieved a $1.0 million development milestone, which was paid with a corresponding credit received from Arcturus for prior research and collaboration activities. The Company is also obligated to pay Arcturus royalties on any net sales of products incorporating the licensed intellectual property that may range from a mid- single-digit to low double-digit percentage. There were no material expenses for this arrangement during the years ended December 31, 2023, 2022, and 2021.

In June 2019, the Company entered into an Equity Purchase Agreement and an amendment to the Research Collaboration and License Agreement, or License Agreement, to expand the field of use and increase the number of disease targets to include mRNA, DNA and siRNA therapeutics for up to 12 rare diseases. Pursuant to the agreements, the Company paid $6.0 million in cash upfront to Arcturus and purchased 2,400,000 shares of Arcturus’ common stock at a stated value of $10.00 per share, resulting in a total of $30.0 million of consideration paid at the close of the transaction. As a result, the Company received expanded license rights under the License Agreement, Arcturus common stock, and an option to purchase an additional 600,000 shares of Arcturus’ common stock at $16.00 per share. In May 2020, the Company exercised its option to purchase 600,000 shares of Arcturus common stock for a total purchase price of $9.6 million.

The Company’s investment in Arcturus was accounted at fair value, as the fair value was readily determinable. During the year ended December 31, 2022, the Company sold 500,000 shares of Arcturus common stock, at a weighted-average price of $20.39 per share. As of December 31, 2022, the Company held no shares of Arcturus common stock.

The changes in the fair value of the Company’s equity investment in Arcturus were as follows (in thousands):


	Arcturus Common Stock
December 31, 2021	$	18,505
Change in fair value		(8,411	)
Sale of shares		(10,094	)
December 31, 2022	$	—

Daiichi Sankyo

In March 2020, the Company executed a License and Technology Access Agreement, or the License Agreement, with Daiichi Sankyo Co., Ltd., or Daiichi Sankyo. Pursuant to the License Agreement, the Company granted Daiichi Sankyo a non-exclusive license to intellectual property, including know-how and patent applications, with respect to its Pinnacle PCLTM producer cell line platform, or Pinnacle PCL Platform, and HEK293 transient transfection manufacturing technology platforms for AAV-based gene therapy products.

Under the terms of the License Agreement, Daiichi Sankyo made an upfront payment of $125.0 million and an additional $25.0 million upon completion of the technology transfer of the Pinnacle PCL Platform and HEK293 platform. Daiichi Sankyo reimbursed the Company for all costs associated with the transfer of the manufacturing technology.

The Company also entered into a Stock Purchase Agreement, or SPA, with Daiichi Sankyo, pursuant to which Daiichi Sankyo purchased 1,243,913 shares of the Company’s common stock in exchange for $75.0 million in cash during the first quarter of 2020. The fair market value of the common stock issued to Daiichi Sankyo was $55.3 million based on the stock price of $44.43 per share on the date of issuance, resulting in a $19.7 million premium on the SPA.

In June 2020, the Company executed a subsequent license agreement, or the Sublicense Agreement, with Daiichi Sankyo for transfer of certain technology in consideration for an upfront payment of $8.0 million and annual maintenance fees, milestone payments, and royalties on any net sales of products incorporating the licensed intellectual property.

The Company evaluated the License Agreement and the Sublicense Agreement under ASC 606 and determined that the performance obligations under the agreements are (i) intellectual property with respect to its Pinnacle PCL Platform and HEK293 transient transfection manufacturing technology platform together with the initial technical assistance and technology transfer services, and (ii) the transfer of any know-how and improvements after the completion of the initial technology transfer through the end of the three year technology transfer period.

The Company allocated the total transaction price to the two performance obligations on a relative stand-alone selling price basis. Revenue allocated to the intellectual property and the technology transfer services was recognized over an initial period which was completed during the first quarter of 2022, measuring the progress toward complete satisfaction of the individual performance obligation using an input measure. Revenue for know-how and improvements after the completion of technology transfer was recognized on a straight-line basis over the remaining technology transfer period, which ended in March 2023, as it was expected that Daiichi Sankyo would receive and consume the benefits consistently throughout the period. The Company’s current obligations under the License Agreement and the Sublicense Agreement were completed following the conclusion of the technology transfer period. Total revenue recognized under the arrangement through December 31, 2023 was $183.3 million.

The Company recognized $1.5 million, $7.7 million, and $85.0 million for the years ended December 31, 2023, 2022, and 2021, respectively, in revenue related to this arrangement. Accordingly, the Company recorded contract liabilities of nil and $1.5 million, net, for this arrangement as of December 31, 2023 and 2022, respectively.

Mereo

In December 2020, the Company entered into a License and Collaboration Agreement with Mereo to collaborate on the development of setrusumab. Under the terms of the agreement, the Company will lead future global development of setrusumab in both pediatric and adult patients with OI. The Company was granted an exclusive license to develop and commercialize setrusumab in the U.S., Turkey, and the rest of the world, excluding the European Economic Area, United Kingdom, and Switzerland, or the

Mereo Territory, where Mereo retains commercial rights. Each party will be responsible for post-marketing commitments and commercial supply in their respective territories.

Upon the closing of the transaction in January 2021, the Company made a payment of $50.0 million to Mereo and will be required to make payments of up to $254.0 million upon the achievement of certain clinical, regulatory, and commercial milestones. The Company will pay for all global development costs as well as tiered double-digit percentage royalties to Mereo on net sales in the U.S., Turkey, and the rest of the world (excluding the Mereo Territory), and Mereo will pay the Company a fixed double-digit percentage royalty on net sales in the Mereo Territory.

Although Mereo is a variable interest entity, the Company is not the primary beneficiary as it does not have the power to direct the activities that would most significantly impact the economic performance of Mereo. Prior to the achievement of certain development milestones, all consideration paid to Mereo represents rights to potential future benefits associated with Mereo’s in-process research and development activities, which have not reached technological feasibility and have no alternative future use.

For the years ended December 31, 2023, 2022, and 2021, the Company recorded research and development expense of $9.0 million for the achievement of a clinical milestone, nil, and $50.0 million for the upfront payment, respectively.

Regeneron

In January 2022, the Company announced a collaboration with Regeneron Pharmaceuticals, or Regeneron, to commercialize Evkeeza for HoFH outside of the U.S. Evkeeza is approved in the U.S., where it is marketed by Regeneron, and in the EU and U.K. as a first-in-class therapy for use together with diet and other low-density lipoprotein-cholesterol-lowering therapies to treat adults and adolescents aged 12 years and older with HoFH. Pursuant to the terms of the agreement, the Company received the rights to develop, commercialize and distribute the product for HoFH in countries outside of the U.S. The Company is obligated to pay up to $63.0 million in future milestone payments, contingent upon the achievement of certain regulatory and sales milestones. The Company may share in certain costs for global trials led by Regeneron and also received the right to opt into other potential indications.

The collaboration agreement is within the scope of ASC 808 which provides guidance on the presentation and disclosure of collaborative arrangements. As the Company would be the principal in future sale transactions with the customer, the Company will recognize product sales and cost of sales in the period the related sales occur and the related revenue recognition criteria are met. Under the collaboration agreement, Regeneron supplies the product and charges the Company a transfer price from the low 20% range up to 40% on net sales, which is recognized as cost of sales in the Company’s Statement of Operations.

The Company paid Regeneron a $30.0 million upfront payment upon the closing of the transaction in January 2022, and during the year ended December 31, 2023, a $10.0 million regulatory milestone was achieved. As these payments are for the Company’s use of intellectual property for Evkeeza for HoFH, they were recorded as intangible assets. See Note 5 for additional details.

Under the collaboration agreement, the Company reimbursed Regeneron for development costs of $7.6 million, $7.3 million, and nil for the years ended December 31, 2023, 2022, and 2021, respectively, which were recorded as research and development expense on the Consolidated Statements of Operations. The Company had collaboration payables for this arrangement included in accrued liabilities on the Consolidated Balance Sheets of $10.6 million and $6.8 million as of December 31, 2023 and December 31, 2022, respectively. Additionally, Regeneron is owed a transfer price fee and royalties on certain revenues and the Company recorded amounts owed to Regeneron of $0.7 million in cost of sales on the Consolidated Statements of Operations for the year ended December 31, 2023.

Abeona

In May 2022, the Company announced an exclusive License Agreement for the AAV gene therapy for UX111 with Abeona for the treatment of MPS IIIA. Under the terms of the agreement, the Company assumed responsibility for the UX111 program and in return, Abeona is eligible to receive tiered royalties of up to 10% on net sales and commercial milestone payments of up to $30.0 million following regulatory approval of the product. Additionally, the Company entered into an Assignment and Assumption Agreement with Abeona to transfer and assign to the Company the exclusive license agreement between Nationwide Children’s Hospital, or NCH, and Abeona for certain rights related to UX111. Under this agreement, NCH is eligible to receive from the Company up to $1.0 million in development and regulatory milestones as well as royalties in the low single-digits of net sales.

The Company is obligated to pay Abeona certain prior development costs and other transition costs related to UX111. Prior to product regulatory approval, all consideration paid to Abeona represents rights to potential future benefits associated with Abeona’s in-process research and development activities, which have not reached technological feasibility and have no alternative future use. Accordingly, the value of the acquired intellectual property rights and clinical inventory as well as prior development costs and transition costs of $3.1 million, were recorded as research and development expense for the year ended December 31, 2022. The Company did not incur any other material costs related to this agreement in the years presented.

Solid Biosciences, Inc.

In October 2020, the Company entered into a strategic Collaboration and License Agreement with Solid Biosciences Inc., or Solid, and received an exclusive license for any pharmaceutical product that expresses Solid’s proprietary microdystrophin construct from AAV8 and variants thereof in clade E for use in the treatment of Duchenne muscular dystrophy and other diseases resulting from lack of functional dystrophin, including Becker muscular dystrophy. The Company is collaborating to develop products that combine Solid’s differentiated microdystrophin construct, the Company’s Pinnacle PCL Platform, and the Company’s AAV8 variants. Solid is providing development support and was granted an exclusive option to co-invest in products the Company develops for profit-share participation in certain territories. On a product-by-product basis, the Company is obligated to make development milestone payments of up to $25.0 million, regulatory milestone payments of up to $65.0 million, and commercial milestone payments of up to $165.0 million, if such milestones are achieved, as well as royalties on any net sales of products incorporating the licensed intellectual property that range from a low to mid-double-digit percentage. The royalty rate changes to mid- to high double-digit percentage if Solid decides to co-invest in the product.

The Company also entered into a Stock Purchase Agreement and the Investor Agreement with Solid, pursuant to which, the Company purchased 7,825,797 shares of Solid’s common stock for an aggregate purchase price of $40.0 million. In October 2022, Solid announced a 1 for 15 reverse stock split. After the split, the Company held 521,719 shares of Solid's common stock. The Company’s investment in Solid is being accounted at fair value, as the fair value is readily determinable. The Company recorded the common stock investment at $26.8 million on the transaction date, which was based on the quoted market price on the closing date.

Although Solid is a variable interest entity, the Company is not the primary beneficiary as it does not have the power to direct the activities that would most significantly impact the economic performance of Solid. Prior to the achievement of certain development milestones, all consideration paid to Solid represents rights to potential future benefits associated with Solid’s in-process research and development activities, which have not reached technological feasibility and have no alternative future use. Accordingly, the remaining $13.2 million of the total $40.0 million paid as consideration was attributed to the license rights obtained and was recorded as in-process research and development expense during the year ended December 31, 2020.

The changes in the fair value of the Company’s investment in Solid’s common stock were as follows (in thousands):


	Solid Common Stock
December 31, 2021	$	13,695
Change in fair value		(10,888	)
December 31, 2022		2,807
Change in fair value		397
December 31, 2023	$	3,204

Balance Sheet Components (Tables)

12 Months Ended

Dec. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Summary of Cash Equivalents and Marketable Debt Securities Classified as Available For Sale Securities

The fair values of cash equivalents and marketable debt securities classified as available-for-sale securities consisted of the following (in thousands):


	December 31, 2023
			Gross Unrealized
	Amortized Cost		Gains		Losses			Estimated Fair Value
Money market funds	$	162,289	$	—	$	—		$	162,289
Certificates of deposit and time deposits		17,986		—		—			17,986
Corporate bonds		214,792		711		(337	)		215,166
Commercial paper		20,620		—		—			20,620
Asset-backed securities		2,715		—		(3	)		2,712
U.S. Government Treasury and agency securities		316,160		982		(100	)		317,042
Total	$	734,562	$	1,693	$	(440	)	$	735,815


	December 31, 2022
			Gross Unrealized
	Amortized Cost		Gains		Losses			Estimated Fair Value
Money market funds	$	102,847	$	—	$	—		$	102,847
Certificates of deposit and time deposits		25,972		—		—			25,972
Corporate bonds		432,211		87		(4,700	)		427,598
Commercial paper		135,393		—		—			135,393
Asset-backed securities		12,002		—		(22	)		11,980
U.S. Government Treasury and agency securities		157,933		320		(1,263	)		156,990
Debt securities in government-sponsored entities		16,005		—		(150	)		15,855
Total	$	882,363	$	407	$	(6,135	)	$	876,635

Summary of Inventory

Inventory consists of the following (in thousands):


	December 31,
	2023		2022
Work-in-process	$	18,859	$	17,486
Finished goods		15,110		9,280
Total inventory	$	33,969	$	26,766

Summary of Property, Plant and Equipment, Net

Property, plant, and equipment, net consists of the following (in thousands):


		December 31,
	Useful life (years)	2023			2022
Building	20-30	$	181,356		$	2,798
Leasehold improvements	Shorter of lease term or estimated useful life		58,683			43,941
Research and development equipment	5		56,347			50,291
Furniture and office equipment	5		6,419			5,540
Computer equipment and software	3-5		16,196			13,876
Manufacturing equipment	5-15		37,297			570
Land	Not applicable		16,619			16,619
Construction-in-progress	Not applicable		867			189,448
Other	Varies by asset		183			24
Property, plant, and equipment, gross			373,967			323,107
Less: accumulated depreciation			(83,401	)		(63,381	)
Property, plant, and equipment, net		$	290,566		$	259,726

Summary of Accrued Liabilities

Accrued liabilities consists of the following (in thousands):


	December 31,
	2023		2022
Research, clinical study, and manufacturing expenses	$	65,326	$	73,558
Payroll and related expenses		82,936		78,938
Other		48,224		52,182
Total accrued liabilities	$	196,486	$	204,678

- Definition

Tabular disclosure of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-9

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
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-Subparagraph (a)
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-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
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-Name Accounting Standards Codification
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-Paragraph 2
-Subparagraph (aa)
-Publisher FASB
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Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef
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-SubTopic 10
-Name Accounting Standards Codification
-Section 50
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-Subparagraph (aaa)
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-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
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-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
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-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 12: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

+ Details

Intangible Assets, Net - Schedule of Expected Amortization of the Intangible Assets (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Intangible Assets, Net (Excluding Goodwill) [Abstract]
2024	$ 4,903
2025	4,903
2026	4,903
2027	4,462
2028	4,022
Thereafter	14,078
Total	$ 37,271

Leases - Schedule of Maturities of Lease Liabilities and the Reconciliation of Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Operating
2024	$ 16,234
2025	11,932
2026	8,430
2027	5,867
2028	5,887
Thereafter	6,009
Total future lease payments	54,359
Less: Amount representing interest	(11,190)
Present value of future lease payments	43,169
Less: Lease liabilities, current	$ (12,595)
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Less: Lease liabilities, current
Lease liabilities, non-current	$ 30,574
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Non-current lease liability
Future Minimum Lease Payments - Operating and Financing Leases
Less: Lease liabilities, current	$ (12,595)	$ (11,779)
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Less: Lease liabilities, current
Non-current lease liability	$ 30,574	$ 19,814
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Non-current lease liability

Intangible Assets, Net

12 Months Ended

Dec. 31, 2023

Intangible Assets, Net (Excluding Goodwill) [Abstract]

Intangible Assets, Net

Intangible Assets, net

Indefinite-lived Intangibles

The Company has IPR&D assets of $129.0 million as of December 31, 2023 and 2022. IPR&D assets represent the fair value of acquired programs to develop an AAV gene therapy for OTC deficiency and to develop an AAV gene therapy for glycogen storage disease type Ia. The fair value of IPR&D assets acquired was determined based on the discounted present value of each research project’s projected cash flows using an income approach, including the application of probability factors related to the likelihood of success of the program reaching final development and commercialization. Additionally, the projections consider the relevant market sizes and growth factors, estimated future cash flows from product sales resulting from completed products and in-process projects and timing and costs to complete the in-process projects. The rates utilized to discount the net cash flows to their present value are commensurate with the stage of development of the projects and uncertainties in the economic estimates used in the projections. IPR&D assets are considered to be indefinite-life until the completion or abandonment of the associated research and development efforts.

Finite-lived Intangibles

Subsequent to the FDA approval of Dojolvi for the treatment of LC-FAOD in 2020, the Company recorded $4.8 million for the attainment of various development and commercial milestones as finite-lived intangible assets which are amortized over a weighted-average useful life of 5.7 years.

In January 2022, the Company announced a collaboration with Regeneron to commercialize Evkeeza for HoFH outside of the U.S. Upon closing of the transaction in January 2022, the Company paid Regeneron a $30.0 million upfront payment. During the year ended December 31, 2023, a $10.0 million regulatory milestone was achieved. As both the upfront payment and the regulatory milestone are related to the Company’s use of intellectual property for Evkeeza for HoFH, these amounts were recorded as intangible assets, which are amortized over a weighted-average useful life of ten years.

The Company's intangible assets were as follows:


	December 31, 2023
	Gross Carrying Amount		Weighted-Average Life (Years)		Accumulated Amortization			Net Carrying Amount
Indefinite-lived intangibles	$	129,000		—	$	—		$	129,000
Finite-lived intangibles		44,775		9.6		(7,504	)		37,271
Total intangible assets	$	173,775		—	$	(7,504	)	$	166,271


	December 31, 2022
	Gross Carrying Amount		Weighted-Average Life (Years)		Accumulated Amortization			Net Carrying Amount
Indefinite-lived intangibles	$	129,000		—	$	—		$	129,000
Finite-lived intangibles		34,775		9.9		(3,670	)		31,105
Total intangible assets	$	163,775		—	$	(3,670	)	$	160,105

The Company recorded costs of sales of $3.8 million, $3.2 million and $0.3 million for the years ended December 31, 2023, 2022, and 2021, respectively, related to the amortization of the intangible assets.

The expected amortization of the intangible assets, as of December 31, 2023, for each of the next five years and thereafter is as follows:


2024	$	4,903
2025		4,903
2026		4,903
2027		4,462
2028		4,022
Thereafter		14,078
Total	$	37,271

License and Research Agreements - Abeona - Additional Information (Details) - Abeona - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	May 31, 2022	Dec. 31, 2023	Dec. 31, 2022
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Other costs			$ 0.0
Development and transition costs			$ 3.1
Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Eligible future milestone payments		$ 1.0
License and Collaboration Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Percentage of royalty on net sales receives		10.00%
Commercial milestone payments	$ 30.0

Related Party Transaction	12 Months Ended
Related Party Transaction	Dec. 31, 2023
Related Party Transactions [Abstract]
Related Party Transaction	16. Related Party Transaction In July 2022, the Company entered into an agreement with a non-profit foundation in which two members of the Company’s board of directors, including the Company’s Chief Executive Officer, also serve as board members of the foundation, whereby an aggregate $1.0 million contribution is being paid to the foundation over a four-year period, beginning in the third quarter of 2022, to support rare disease education and awareness. As a result, the Company recorded $0.3 million and $0.3 million as research and development expense for this agreement for the years ended December 31, 2023 and 2022, respectively.

- Definition

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section 50
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-URI https://asc.fasb.org//1943274/2147480990/946-20-50-5

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org//1943274/2147480990/946-20-50-6

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-Subparagraph (c)
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (e)
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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-Section S99
-Paragraph 1
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org//850/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483326/850-10-50-1

+ Details

Revenue - Summary of Disaggregation of Total Revenues (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation Of Revenue [Line Items]
Total revenues	$ 434,249	$ 363,329	$ 351,406
North America
Disaggregation Of Revenue [Line Items]
Total revenues	307,149	281,088	301,110
Latin America
Disaggregation Of Revenue [Line Items]
Total revenues	77,342	44,711	23,636
Europe
Disaggregation Of Revenue [Line Items]
Total revenues	47,534	36,369	26,660
Japan
Disaggregation Of Revenue [Line Items]
Total revenues	$ 2,224	$ 1,161	$ 0

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 924
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-Name Accounting Standards Codification
-Section S99
-Paragraph 1
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-URI https://asc.fasb.org//1943274/2147479806/606-10-50-4

+ Details

Net Loss per Share - Outstanding Shares of Common Stock Equivalents Excluded from Computation of Diluted Net Loss per Share (Details) - shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common stock equivalents excluded from computation of diluted net loss per share	14,160,736	11,298,516	8,217,574
Options to Purchase Common Stock, RSUs, and PSUs
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common stock equivalents excluded from computation of diluted net loss per share	14,152,286	11,290,935	8,214,063
Employee Stock Purchase Plan
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common stock equivalents excluded from computation of diluted net loss per share	8,450	7,581	3,511

Stock-Based Awards (Tables)

12 Months Ended

Dec. 31, 2023

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Summary of Activity Under Stock Option Plans Including 2011 Plan, 2014 Plan and 2023 Plan

Stock Option Activity

The following table summarizes activity under the Company’s stock option plans and related information:


	Options Outstanding
	Number of Options			Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Term (Years)	Aggregate Intrinsic Value
							(In thousands)
Outstanding — December 31, 2022		7,773,367		$	72.56	6.60	$	8,476
Options granted		2,123,256			45.05
Options exercised		(209,793	)		13.07
Options cancelled		(899,118	)		71.56
Outstanding — December 31, 2023		8,787,712			67.43	6.39		7,558
Vested and exercisable — December 31, 2023		5,415,110			73.28	4.96		1,214
Vested and expected to vest — December 31, 2023		8,461,973			67.96	6.29		6,794

Summary of Stock-Based Compensation Expense

Total stock-based compensation recognized was as follows (in thousands):


	Year Ended December 31,
	2023		2022		2021
Cost of sales	$	1,166	$	902	$	871
Research and development		74,531		74,464		59,097
Selling, general and administrative		59,516		55,002		45,011
Total stock-based compensation expense	$	135,213	$	130,368	$	104,979

Fair Value of Stock Option Awards Granted Estimated Using Black-Scholes Option-Pricing Model

The fair value of stock option awards granted was estimated at the date of grant using a Black-Scholes option-pricing model with the following weighted-average assumptions:


	Year Ended December 31,
	2023	2022	2021
Expected term (years)	6.07	6.07	6.06
Expected volatility	55%	56%	60%
Risk-free interest rate	4.2%	2.0%	1.0%
Expected dividend rate	0.0%	0.0%	0.0%

The fair value of PSOs granted was estimated at the date of grant using a Black-Scholes option-pricing model with the following weighted-average assumptions:


		Year Ended December 31,
		2022
Expected term in years		3.60
Expected volatility		57%
Risk-free interest rate		1.5%
Expected dividend rate		0.0%

Restricted Stock Units

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Summary of Activity Under Stock Units from 2014 Plan

The following table summarizes activity under the Company’s Restricted Stock Units, or RSU, plans and related information:


	RSUs Outstanding
	Number of Shares			Weighted- Average Grant Date Fair Value
Unvested — December 31, 2022		2,129,153		$	75.11
RSUs granted		2,447,170			44.52
RSUs vested		(738,130	)		73.99
RSUs cancelled		(394,081	)		61.22
Unvested — December 31, 2023		3,444,112			55.21

Performance Stock Units

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Summary of Activity Under Stock Units from 2014 Plan

The following table summarizes activity under the Company’s Performance Stock Units, or PSUs and related information:


	PSUs Outstanding
	Number of Shares			Weighted- Average Grant Date Fair Value
Unvested — December 31, 2022		209,230		$	98.09
PSUs granted		362,470			50.29
PSUs vested		(27,581	)		141.86
PSUs cancelled		(38,013	)		106.80
Unvested — December 31, 2023		506,106			60.82

Performance Stock Options [Member]

Share Based Compensation Arrangement By Share Based Payment Award [Line Items]

Summary of Activity Under Stock Option Plans Including 2011 Plan, 2014 Plan and 2023 Plan

The following table summarizes activity under the Company’s Performance Stock Option, or PSO, plans and related information:


	PSOs Outstanding
	Number of Options			Weighted- Average Exercise Price		Weighted-Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value
Outstanding — December 31, 2022		1,624,599		$	67.37		4.14	$	—
PSOs cancelled		(243,601	)		67.37
Outstanding — December 31, 2023		1,380,998			67.37		3.15		—
Vested and exercisable — December 31, 2023		117,865			67.37		3.09		—
Vested and expected to vest — December 31, 2023		983,173			67.37		3.14		—

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2012	Dec. 31, 2011
Tax Credit Carryforward [Line Items]
Current state income tax expense	$ (60)	$ 7,336	$ 1,044
Deferred tax assets net operating loss, federal tax credits				$ 200	$ 200
Deferred tax assets net operating loss carryforwards	266,253	231,835
Valuation allowance increased	141,300	193,800
Effective income tax rate unrecognized tax benefits	1,300
Deferred tax liability increase (decrease), net	(1,600)
Deferred income tax expense	1,608	1,640
Recognized accrued interest and penalties	200	0	$ 0
Undistributed earnings of foreign subsidiaries	10,800
Federal
Tax Credit Carryforward [Line Items]
Deferred tax assets operating loss carryforwards subject to expiration	$ 1,004,800	756,600
Operating loss carryforwards expiration year	2031
Tax credit carryforwards	$ 46,900	32,600
Tax credit carryforwards expiration year	2030
Deferred tax assets net operating loss carryforwards				3,600	3,600
Federal \| Orphan Drug Credits [Member]
Tax Credit Carryforward [Line Items]
Deferred tax assets operating loss carryforwards subject to expiration	$ 269,600	239,300
Operating loss carryforwards expiration year	2031
State
Tax Credit Carryforward [Line Items]
Current state income tax expense	$ 4,800	6,100
Deferred tax assets operating loss carryforwards subject to expiration	$ 659,900	710,000
Operating loss carryforwards expiration year	2031
Tax credit carryforwards	$ 74,400	$ 59,900
Deferred tax assets net operating loss carryforwards				$ 3,600	$ 3,600
International
Tax Credit Carryforward [Line Items]
Current state income tax expense	$ 3,000

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Accounting Policies [Abstract]
Allowance for doubtful accounts	$ 0	$ 0
Unrecognized tax benefits related to interest or penalties	$ 0

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Components of Company's Loss Before Income Taxes

The components of the Company’s loss before income taxes were as follows (in thousands):


	Year Ended December 31,
	2023		2022			2021
Domestic	$	608,166	$	703,411		$	455,314
Foreign		298		(1,686	)		(2,333	)
Total loss before income taxes	$	608,464	$	701,725		$	452,981

Components of Company's Income Tax Provision

The components of the Company’s income tax provision were as follows (in thousands):


	Year Ended December 31,
	2023			2022			2021
Current provision for income taxes:
Federal	$	—		$	—		$	—
State		(3,187	)		6,062			(14	)
International		3,127			1,274			1,058
Total current tax provision		(60	)		7,336			1,044
Deferred tax provision:
Federal		—			—			—
State		(1,608	)		(1,640	)		—
International		(157	)		—			—
Total deferred tax provision		(1,765	)		(1,640	)		—
Total (benefit from) provision for income taxes	$	(1,825	)	$	5,696		$	1,044

Effective Tax Rate of Provision for Income Taxes from Federal Statutory Rate

The effective tax rate of our provision for income taxes differs from the federal statutory rate as follows:


	Year Ended December 31,
	2023				2022				2021
Federal statutory income tax rate		21.0		%		21.0		%		21.0		%
State income taxes, net of federal benefit		0.8				(0.4	)			—
Federal tax credits		7.3				5.9				7.2
Other		(0.7	)			(0.1	)			0.5
Nondeductible permanent items		(0.3	)			(0.6	)			(0.8	)
Stock-based compensation		(1.8	)			(1.2	)			1.3
Uncertain tax positions		(1.4	)			(1.2	)			(1.4	)
Change in valuation allowance		(24.1	)			(24.0	)			(27.9	)
Foreign rate differential		(0.5	)			(0.2	)			(0.1	)
Provision for income taxes		0.3		%		(0.8	)	%		(0.2	)	%

Schedule of Tax Effect of Temporary Differences to Significant Portions of Deferred Tax Assets

The tax effect of temporary differences that give rise to significant portions of the deferred tax assets is presented below (in thousands):


	Year Ended December 31,
	2023			2022
Deferred tax assets:
Loss carryforwards	$	266,253		$	231,835
Tax credits		305,198			260,546
Stock options		44,795			39,784
Accruals and reserves		27,694			27,029
Fixed assets and intangibles		33,853			39,233
Liabilities for sales of future royalties		205,400			214,900
Basis difference in equity investments		8,423			8,971
Capitalized research and development costs		149,898			75,335
Other		281			3,028
Gross deferred tax assets		1,041,795			900,661
Valuation allowance		(1,035,836	)		(894,518	)
Total deferred tax assets		5,959			6,143
Deferred tax liabilities:
In-process research and development		(30,688	)		(31,667	)
Right-of-use lease assets		(5,329	)		(6,143	)
Gross deferred tax liabilities		(36,017	)		(37,810	)
Net deferred tax liabilities	$	(30,058	)	$	(31,667	)

Unrecognized Tax Benefits

A reconciliation of the Company’s unrecognized tax benefits follows (in thousands):


	December 31,
	2023		2022			2021
Balance at beginning of year	$	66,794	$	55,360		$	46,662
Additions based on tax positions related to current year		12,562		11,316			8,542
Additions for tax positions of prior years		642		377			356
Reductions for tax positions of prior years		—		(259	)		(200	)
Balance at end of year	$	79,998	$	66,794		$	55,360

License and Research Agreements - Share of Collaboration and Royalty Revenue Related to Crysvita (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation Of Revenue [Line Items]
Collaboration and license revenue	$ 434,249	$ 363,329	$ 351,406
Collaboration and Royalty \| Kyowa Kirin Collaboration
Disaggregation Of Revenue [Line Items]
Collaboration and license revenue	328,054	279,394	210,815
Collaboration and Royalty \| Kyowa Kirin Collaboration \| Profit Share Territory
Disaggregation Of Revenue [Line Items]
Collaboration and license revenue	231,574	215,024	171,198
Royalty revenue
Disaggregation Of Revenue [Line Items]
Collaboration and license revenue	182,652	21,692	17,951
Royalty revenue \| Kyowa Kirin Collaboration \| Profit Share Territory
Disaggregation Of Revenue [Line Items]
Collaboration and license revenue	113,288	0	0
Royalty revenue \| Kyowa Kirin Collaboration \| Royalty Revenue in European Territory
Disaggregation Of Revenue [Line Items]
Collaboration and license revenue	0	0	244
Product sales
Disaggregation Of Revenue [Line Items]
Collaboration and license revenue	180,413	118,927	77,017
Product sales \| Kyowa Kirin Collaboration
Disaggregation Of Revenue [Line Items]
Collaboration and license revenue	75,697	42,678	21,422
Collaboration Revenue \| Kyowa Kirin Collaboration \| Profit Share Territory
Disaggregation Of Revenue [Line Items]
Collaboration and license revenue	69,705	215,024	171,198
Non-cash royalty revenue \| Kyowa Kirin Collaboration \| Profit Share Territory
Disaggregation Of Revenue [Line Items]
Collaboration and license revenue	48,581	0	0
Non-cash royalty revenue \| Kyowa Kirin Collaboration \| Royalty Revenue in European Territory
Disaggregation Of Revenue [Line Items]
Collaboration and license revenue	$ 20,783	$ 21,692	$ 17,951

Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		12 Months Ended		32 Months Ended
	Oct. 31, 2023	May 31, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2023
Stockholders Equity Line Items
Stock sold in at-the-market offering			1,175,584
Net proceeds from at-the-market offering			$ 53.3
Pre Funded Warrant
Stockholders Equity Line Items
Number of warrants exercised			0		0
Underwritten Public Offering
Stockholders Equity Line Items
Common stock shares sold	9,833,334
Shares purchased by underwriters	1,500,000
Public offering price	$ 30
Underwritten Public Offering \| Pre Funded Warrant
Stockholders Equity Line Items
Net proceeds from sale of common stock	$ 326.5
Underwritten Public Offering Shares	1,666,722
Pre-funded warrant price	$ 29.999
Common stock warrants, exercise price	$ 0.001
Open Market Sale
Stockholders Equity Line Items
Common stock shares sold				0
Stock sold in at-the-market offering					2,225,956
Net proceeds from at-the-market offering					$ 132.2
Option to sell common stock aggregate offering price		$ 350.0

License and Research Agreements - Baylor Research Institute - Additional Information (Details) - Baylor Research Institute - Development Milestones - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Future contingent milestone payments	$ 7.5
Research and Development Expense
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contingent milestone payment	$ 0.0	$ 2.5

Fair Value Measurements

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

Fair Value Measurements

Financial assets and liabilities are recorded at fair value. The carrying amount of certain financial instruments, including cash and cash equivalents, accounts receivable, accounts payable and accrued liabilities approximate fair value due to their relatively short maturities. Assets and liabilities recorded at fair value on a recurring basis in the balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows:

Level 1—Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date;

Level 2—Inputs are observable, unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted quoted prices for identical or similar assets or liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; and

Level 3—Unobservable inputs that are significant to the measurement of the fair value of the assets or liabilities that are supported by little or no market data.

The Company’s financial instruments consist of Level 1, Level 2, and Level 3 assets. Where quoted prices are available in an active market, securities are classified as Level 1. Money market funds and U.S. Government treasury bills are classified as Level 1. Level 2 assets consist primarily of corporate bonds, asset backed securities, commercial paper, U.S. Government Treasury and agency securities, and debt securities in government-sponsored entities based upon quoted market prices for similar movements in active markets, quoted prices for identical or similar instruments in markets that are not active and model-based valuation techniques for which all significant inputs are observable in the market or can be corroborated by observable market data for substantially the full term of the assets. Where applicable these models project future cash flows and discount the future amounts to a present value using market-based observable inputs obtained from various third-party data providers, including but not limited to, benchmark yields, interest rate curves, reported trades, broker/dealer quotes and reference data.

The Company determines the fair value of its equity investments in Solid Biosciences, Inc., or Solid, by using the quoted market prices, which are Level 1 fair value measurements.

The following tables set forth the fair value of the Company’s financial assets remeasured on a recurring basis based on the three-tier fair value hierarchy (in thousands):


	December 31, 2023
	Level 1		Level 2		Level 3		Total
Financial Assets:
Money market funds	$	162,289	$	—	$	—	$	162,289
Certificates of deposit and time deposits		—		17,986		—		17,986
Corporate bonds		—		215,166		—		215,166
Commercial paper		—		20,620		—		20,620
Asset-backed securities		—		2,712		—		2,712
U.S. Government Treasury and agency securities		57,437		259,605		—		317,042
Investment in Solid common stock		3,204		—		—		3,204
Deferred compensation assets		—		10,220		—		10,220
Total financial assets	$	222,930	$	526,309	$	—	$	749,239

Financial Liabilities:
Deferred compensation liabilities	$	—	$	10,365	$	—	$	10,365


	December 31, 2022
	Level 1		Level 2		Level 3		Total
Financial Assets:
Money market funds	$	102,847	$	—	$	—	$	102,847
Certificates of deposit and time deposits		—		25,972		—		25,972
Corporate bonds		—		427,598		—		427,598
Commercial paper		—		135,393		—		135,393
Asset-backed securities		—		11,980		—		11,980
U.S. Government Treasury and agency securities		27,645		129,345		—		156,990
Debt securities in government-sponsored entities		—		15,855		—		15,855
Investment in Solid common stock		2,807		—		—		2,807
Deferred compensation assets		—		4,575		—		4,575
Total financial assets	$	133,299	$	750,718	$	—	$	884,017

Financial Liabilities:
Deferred compensation liabilities	$	—	$	4,657	$	—	$	4,657

Deferred compensation assets are recorded at fair value in other non-current assets in the Consolidated Balance Sheets. There have been no significant gains or losses on deferred compensation assets for the periods presented.

Deferred compensation liabilities consist of short-term liabilities of $0.2 million and nil as of December 31, 2023 and 2022, respectively, included in accrued liabilities on the Consolidated Balance Sheets, and long-term liabilities of $10.1 million and $4.7 million as of December 31, 2023 and 2022, respectively, included in other non-current liabilities on the Consolidated Balance Sheets.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Balance at beginning of year	$ 66,794	$ 55,360	$ 46,662
Additions based on tax positions related to current year	12,562	11,316	8,542
Additions for tax positions of prior years	642	377	356
Reductions for tax positions of prior years	0	(259)	(200)
Balance at end of year	$ 79,998	$ 66,794	$ 55,360

Stock-Based Awards - Summary of Activity Under PSUs from 2014 Plan (Details) - Performance Stock Units	12 Months Ended
	Dec. 31, 2023 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding, Number of Shares, Unvested, Beginning Balance \| shares	209,230
Number of shares, granted \| shares	362,470
Number of shares, vested \| shares	(27,581)
Number of shares, cancelled \| shares	(38,013)
Outstanding, Number of Shares, Unvested, Ending Balance \| shares	506,106
Outstanding, Weighted-Average Grant Date Fair Value, Unvested, Beginning Balance \| $ / shares	$ 98.09
Weighted-Average Grant Date Fair Value, granted \| $ / shares	50.29
Weighted-Average Grant Date Fair Value, vested \| $ / shares	141.86
Weighted-Average Grant Date Fair Value, cancelled \| $ / shares	106.8
Weighted- Average Exercise Price,Outstanding December 31, 2023 \| $ / shares	$ 60.82

Equity

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

Equity

11.

Equity

At-the-Market Offerings

In May 2021, the Company entered into an Open Market Sale Agreement with Jefferies LLC, or Jefferies, pursuant to which the Company may offer and sell shares of the Company’s common stock having an aggregate offering proceeds up to $350.0 million, from time to time, in at-the-market, or ATM, offerings through Jefferies. During the year ended December 31, 2023, there were 1,175,584 shares sold under the ATM resulting in net proceeds of $53.3 million. There were no shares sold under the ATM for year ended December 31, 2022. As of December 31, 2023, the Company has sold a total of 2,225,956 shares under the ATM, resulting in net proceeds of $132.2 million.

Underwritten Public Offering

In October 2023, the Company completed an underwritten public offering in which 9,833,334 shares of common stock were sold, including the exercise in full by the underwriters of their option to purchase an additional 1,500,000 shares, at a public offering price of $30.00 per share. In connection with the offering, the Company sold to certain investors pre-funded warrants, in lieu of common stock, to purchase 1,666,722 shares of common stock at a purchase price of $29.999 per pre-funded warrant, which equals the public offering price per share of common stock less the $0.001 exercise price per share of each pre-funded warrant. The total

proceeds that the Company received from the offering were $326.5 million, net of underwriting discounts and commissions. As of December 31, 2023, none of the pre-funded warrants had been exercised.

The pre-funded warrants were classified as a component of permanent equity in the Company's Consolidated Balance Sheets as they are freestanding financial instruments that are immediately exercisable, do not embody an obligation for the Company to repurchase its own shares and permit the holders to receive a fixed number of shares of common stock upon exercise. All of the shares underlying the pre-funded warrants have been included in the weighted-average number of shares of common stock used to calculate net loss per share, basic and diluted, attributable to common stockholders because the shares may be issued for little or no consideration, are fully vested, and are exercisable after the original issuance date of the pre-funded warrants.

- Definition

The entire disclosure for equity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480237/815-40-50-6

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480008/505-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(e)(1))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//505/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 16
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-16

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

+ Details

Related Party Transaction - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jul. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Related Party Transaction Line Items
Contribution amount paid	$ 1,000
Contribution period	4 years
Research and development		$ 648,449	$ 705,789	$ 497,153
Non Profit Foundation
Related Party Transaction Line Items
Research and development		$ 300	$ 300

Defined Contribution Plan	12 Months Ended
Defined Contribution Plan	Dec. 31, 2023
Defined Contribution Pension And Other Post Retirement Plan Disclosure [Abstract]
Defined Contribution Plan	13. Defined Contribution Plan The Company sponsors a retirement plan in which substantially all of its full-time employees in the U.S. and certain other foreign countries are eligible to participate. Eligible participants may contribute a percentage of their annual compensation to this plan, subject to statutory limitations. The Company recorded $9.7 million, $9.0 million, and $5.5 million as expense related to the plan for the years ended December 31, 2023, 2022, and 2021, respectively.

Defined Contribution Plan - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Contribution Pension And Other Post Retirement Plan Disclosure [Abstract]
Contribution expenses	$ 9.7	$ 9.0	$ 5.5

License and Research Agreements - Regeneron - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Regulatory milestone payments achieved		$ 10,000
Cost of sales		45,209	$ 28,320	$ 16,008
Regeneron Pharmaceuticals Inc
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront payments of collaboration	$ 30,000
Regulatory milestone payments achieved		10,000
Development costs		7,600	7,300	$ 0
Eligible future milestone payments	$ 63,000
Accrued collaboration payables		10,600	$ 6,800
Cost of sales		$ 700
Maximum \| Regeneron Pharmaceuticals Inc
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Profit loss sharing percentage on net sales		40.00%
Minimum \| Regeneron Pharmaceuticals Inc
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Profit loss sharing percentage on net sales	20.00%

License and Research Agreements - Schedule of Changes in Fair Value of Investment in Securities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Common stock, Beginning balance	$ 884,017
Common stock, Ending balance	749,239	$ 884,017
Common Stock \| Solid Biosciences, Inc.
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Common stock, Beginning balance	2,807	13,695
Common stock, Change in fair value	397	(10,888)
Common stock, Ending balance	$ 3,204	$ 2,807

Organization and Basis of Presentation - Additional Information (Details)	12 Months Ended
	Dec. 31, 2023 Segment
Organization And Nature Of Business [Line Items]
Number of reportable segments	1

Organization and Basis of Presentation

12 Months Ended

Dec. 31, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Organization and Basis of Presentation

Ultragenyx Pharmaceutical Inc., or the Company, is a biopharmaceutical company incorporated in Delaware.

The Company is focused on the identification, acquisition, development, and commercialization of novel products for the treatment of serious rare and ultrarare genetic diseases. The Company operates as one reportable segment and has four commercially approved products.

Crysvita® (burosumab) is approved in the United States, or U.S., the European Union, or EU, and certain other regions for the treatment of X-linked hypophosphatemia, or XLH, in adult and pediatric patients one year of age and older. Crysvita is also approved in the U.S. and certain other regions for the treatment of fibroblast growth factor 23, or FGF23-related hypophosphatemia in tumor-induced osteomalacia, or TIO, associated with phosphaturic mesenchymal tumors that cannot be curatively resected or localized in adults and pediatric patients 2 years of age and older.

Mepsevii® (vestronidase alfa) is approved in the U.S., the EU and certain other regions, as the first medicine for the treatment of children and adults with mucopolysaccharidosis VII, or MPS VII, also known as Sly syndrome.

Dojolvi® (triheptanoin) is approved in the U.S. and certain other regions for the treatment of pediatric and adult patients severely affected by long-chain fatty acid oxidation disorders, or LC-FAOD.

Evkeeza® (evinacumab) is approved in the U.S. and the European Economic Area, or EEA, for the treatment of homozygous familial hypercholesterolemia, or HoFH. The Company has exclusive rights to commercialize Evkeeza® (evinacumab) outside of the U.S.

In addition to the approved products, the Company has the following ongoing clinical development programs:

•

UX111 (formerly ABO-102) is an AAV9 gene therapy product candidate for the treatment of patients with Sanfilippo syndrome type A, or MPS IIIA, a rare lysosomal storage disease;

•

DTX401 is an adeno-associated virus 8, or AAV8, gene therapy product candidate for the treatment of patients with glycogen storage disease type Ia, or GSDIa;

•

DTX301 is an AAV8 gene therapy product candidate in development for the treatment of patients with ornithine transcarbamylase, or OTC deficiency, the most common urea cycle disorder;

•

UX143 (setrusumab), which is subject to the Company’s collaboration agreement with Mereo BioPharma 3, or Mereo, is a fully human monoclonal antibody that inhibits sclerostin, a protein that acts on a key bone-signaling pathway and inhibits the activity of bone-forming cells for the treatment of patients with osteogenesis imperfect, or OI;

•

GTX-102 is an antisense oligonucleotide, or ASO for the treatment of Angelman syndrome, a debilitating and rare neurogenetic disorder caused by loss-of-function of the maternally inherited allele of the UBE3A gene.; and

•

UX701 is an adeno-associated virus 9, or AAV9, gene therapy designed to deliver stable expression of a truncated version of the ATP7B copper transporter following a single intravenous infusion to improve copper distribution and excretion from the body and reverse pathological findings of Wilson liver disease;

The Company has sustained operating losses and expects such annual losses to continue over the next several years. The Company’s ultimate success depends on the outcome of its research and development and commercialization activities. Through December 31, 2023, the Company has relied primarily on its sale of equity securities, its revenues from commercial products, its sale of future royalties, and strategic collaboration arrangements to finance its operations. The Company may need to raise additional capital to fully implement its business plans through the issuance of equity, borrowings, or strategic alliances with partner companies. However, if such financing is not available at adequate levels, the Company would need to reevaluate its operating plans.

Balance Sheet Components - Summary of Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Research, clinical study, and manufacturing expenses	$ 65,326	$ 73,558
Payroll and related expenses	82,936	78,938
Other	48,224	52,182
Total accrued liabilities	$ 196,486	$ 204,678

Revenue (Tables)

12 Months Ended

Dec. 31, 2023

Revenue from Contract with Customer [Abstract]

Summary of Disaggregation of Total Revenues

The following table disaggregates total revenues from external customers by product sales, royalty revenue, and collaboration and license revenue (in thousands):


	Year Ended December 31,
	2023		2022		2021

Product sales:
Crysvita	$	75,697	$	42,678	$	21,422
Mepsevii		30,441		20,637		16,035
Dojolvi		70,633		55,612		39,560
Evkeeza		3,642		—		—
Total product sales		180,413		118,927		77,017
Crysvita royalty revenue		182,652		21,692		17,951
Collaboration and license revenue:
Crysvita collaboration revenue in Profit-Share Territory		69,705		215,024		171,198
Crysvita royalty revenue in European Territory		—		—		244
Daiichi Sankyo		1,479		7,686		84,996
Total collaboration and license revenue		71,184		222,710		256,438
Total revenues	$	434,249	$	363,329	$	351,406

The following table disaggregates total revenues based on geographic location (in thousands):


	Year Ended December 31,
	2023		2022		2021
North America	$	307,149	$	281,088	$	301,110
Latin America		77,342		44,711		23,636
Europe		47,534		36,369		26,660
Japan		2,224		1,161		—
Total revenues	$	434,249	$	363,329	$	351,406

Schedule of Sales-Related Accruals and Allowances

The following table presents the activity and ending balances for sales-related accruals and allowances (in thousands):


	Year Ended December 31,
	2023			2022			2021
Balance of product sales reserve at beginning of year	$	11,487		$	7,181		$	3,913
Provisions		18,761			13,525			9,586
Payments		(12,746	)		(9,613	)		(6,120	)
Adjustments		(473	)		394			(198	)
Balance of product sales reserve at end of year	$	17,029		$	11,487		$	7,181

Summary of Changes in Contract Liabilities

The following table presents changes in the contract liabilities for the years ended December 31, 2023 and 2022 (in thousands):


	Year Ended December 31,
	2023			2022
Balance of contract liabilities at beginning of period	$	1,479		$	9,076
Additions		—			89
Deductions		(1,479	)		(7,686	)
Balance of contract liabilities at end of period, net	$	—		$	1,479

Revenue - Summary of Changes in Contract Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Disaggregation of Revenue [Abstract]
Balance of contract liabilities at beginning of period	$ 1,479	$ 9,076
Additions	0	89
Deductions	(1,479)	(7,686)
Balance of contract liabilities at end of period, net	$ 0	$ 1,479

Stock-Based Awards- Summary Activity Under the Performance Stock Option (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Vested and exercisable December 31, 2023	5,415,110
Vested and expected to vest December 31, 2023	8,461,973
Weighted- Average Exercise Price,Weighted Average Exercise Price	$ 73.28
Weighted Average Exercise Price, Vested and expected to vest December 31, 2023	$ 67.96
Weighted-Average Remaining Contractual Term,Vested and expected to vest December 31, 2023	6 years 3 months 14 days
Weighted Average Remaining Contractual Term (Years), Vested and exercisable - December 31, 2023	4 years 11 months 15 days
Aggregate Intrinsic Value, Vested and exercisable - December 31, 2023	$ 1,214
Aggregate Intrinsic Value, Vested and expected to vest - December 31, 2023	$ 6,794
Performance Stock Options [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Outstanding, Number of Shares, Unvested, Beginning Balance	1,624,599
PSOs cancelled	(243,601)
Outstanding, Number of Shares, Unvested, Ending Balance	1,380,998	1,624,599
Vested and exercisable December 31, 2023	117,865
Vested and expected to vest December 31, 2023	983,173
Outstanding, Weighted-Average Grant Date Fair Value, Unvested, Beginning Balance	$ 67.37
Weighted Average Exercise Price ,PSOs cancelled	67.37
Weighted- Average Exercise Price,Outstanding December 31, 2023	67.37	$ 67.37
Weighted- Average Exercise Price,Weighted Average Exercise Price	67.37
Weighted Average Exercise Price, Vested and expected to vest December 31, 2023	$ 67.37
Weighted-Average Remaining Contractual Term,Outstanding at December 31, 2023	3 years 1 month 24 days	4 years 1 month 20 days
Weighted-Average Remaining Contractual Term,Vested and expected to vest December 31, 2023	3 years 1 month 20 days
Weighted Average Remaining Contractual Term (Years), Vested and exercisable - December 31, 2023	3 years 1 month 2 days
Aggregate Intrinsic Value, Outstanding	$ 0	$ 0
Aggregate Intrinsic Value, Vested and exercisable - December 31, 2023	0
Aggregate Intrinsic Value, Vested and expected to vest - December 31, 2023	$ 0

Liabilities for Sales of Future Royalties

12 Months Ended

Dec. 31, 2023

Deferred Revenue Disclosure [Abstract]

Liabilities for Sales of Future Royalties

10.

Liabilities for Sales of Future Royalties

In December 2019, the Company entered into a Royalty Purchase Agreement with RPI. Pursuant to the agreement, RPI paid $320.0 million to the Company in consideration for the right to receive royalty payments effective January 1, 2020, arising from the net sales of Crysvita in the EU, the U.K., and Switzerland under the terms of the Company’s Collaboration and License Agreement with KKC dated August 29, 2013, as amended, or the KKC Collaboration Agreement. The agreement with RPI will automatically terminate, and the payment of royalties to RPI will cease, in the event aggregate royalty payments received by RPI are equal to or greater than $608.0 million prior to December 31, 2030, or in the event aggregate royalty payments received by RPI are less than $608.0 million prior to December 31, 2030, or when aggregate royalty payments received by RPI are equal to $800.0 million.

In July 2022, the Company entered into a Royalty Purchase Agreement with OMERS. Pursuant to the agreement, OMERS paid $500.0 million to the Company in consideration for the right to receive 30% of the future royalty payments due to the Company from KKC based on net sales of Crysvita in the U.S. and Canada under the terms of the KKC Collaboration Agreement. The calculation of royalty payments to OMERS is based on net sales of Crysvita beginning in April 2023 and will expire upon the earlier of the date on which aggregate payments received by OMERS equals $725.0 million or the date the final royalty payment is made to the Company under the KKC Collaboration Agreement.

Proceeds from these transactions were recorded as liabilities for sales of future royalties on the Consolidated Balance Sheets. Upon inception of the respective arrangements, the Company recorded $320.0 million and $500.0 million, net of transaction costs of $5.8 million and $9.1 million for RPI and OMERS, respectively, using the effective interest method over the estimated life of the applicable arrangement. In order to determine the amortization of the liabilities, the Company is required to estimate the total

amount of future royalty payments to be received by the Company and paid to RPI and OMERS, subject to the capped amount, over the life of the arrangements. The excess of future estimated royalty payments (subject to the capped amount) to RPI and OMERS, over the $314.2 million and $491.0 million, respectively, of net proceeds, is recorded as non-cash interest expense over the life of the arrangements. Consequently, the Company estimates an imputed interest on the unamortized portion of the liabilities and records interest expense relating to the transactions. The Company records the royalty revenue arising from the net sales of Crysvita in the applicable territories as royalty revenue in the Consolidated Statements of Operations over the term of the arrangements. Royalties earned under the RPI and OMERS arrangements from inception to December 31, 2023 have been $73.4 million and $48.6 million, respectively.

The Company periodically assesses the expected royalty payments using a combination of historical results, internal projections and forecasts from external sources. To the extent such payments are greater or less than the Company’s initial estimates or the timing of such payments is materially different than its original estimates, the Company will prospectively adjust the amortization of the liabilities and the effective interest rate. The Company’s effective annual interest rates were 6.2% and 7.8%, for RPI and OMERS, respectively, as of December 31, 2023.

There are a number of factors that could materially affect the amount and timing of royalty payments from KKC in the applicable territories, most of which are not within the Company’s control. Such factors include, but are not limited to, the success of KKC’s sales and promotion of Crysvita, changing standards of care, macroeconomic and inflationary pressures, the introduction of competing products, pricing for reimbursement in various territories, manufacturing or other delays, intellectual property matters, adverse events that result in governmental health authority imposed restrictions on the use of Crysvita, significant changes in foreign exchange rates as the royalty payments are made in U.S. dollars, or USD, while significant portions of the underlying sales of Crysvita are made in currencies other than USD, and other events or circumstances that could result in reduced royalty payments from sales of Crysvita, all of which would result in a reduction of royalty revenue and the non-cash interest expense over the life of the arrangement. Conversely, if sales of Crysvita in the relevant territories are more than expected, the royalty revenue and the non-cash interest expense recorded by the Company would be greater over the term of the arrangements.

The following table shows the activity within the liability account (in thousands):



	Liabilities for Sales of Future Royalties
	RPI			OMERS			Total
December 31, 2021	$	351,786		$	—		$	351,786
Net proceeds from sale of future royalties		—			490,950			490,950
Royalty revenue		(21,692	)		—			(21,692	)
Non-cash interest expense		35,095			19,300			54,395
December 31, 2022		365,189			510,250			875,439
Royalty revenue		(20,783	)		(38,524	)		(59,307	)
Non-cash interest expense		32,235			43,200			75,435
December 31, 2023	$	376,641		$	514,926		$	891,567

Intangible Assets, net (Table)

12 Months Ended

Dec. 31, 2023

Intangible Assets, Net (Excluding Goodwill) [Abstract]

Summary of Company's Intangible Assets

The Company's intangible assets were as follows:


	December 31, 2023
	Gross Carrying Amount		Weighted-Average Life (Years)		Accumulated Amortization			Net Carrying Amount
Indefinite-lived intangibles	$	129,000		—	$	—		$	129,000
Finite-lived intangibles		44,775		9.6		(7,504	)		37,271
Total intangible assets	$	173,775		—	$	(7,504	)	$	166,271


	December 31, 2022
	Gross Carrying Amount		Weighted-Average Life (Years)		Accumulated Amortization			Net Carrying Amount
Indefinite-lived intangibles	$	129,000		—	$	—		$	129,000
Finite-lived intangibles		34,775		9.9		(3,670	)		31,105
Total intangible assets	$	163,775		—	$	(3,670	)	$	160,105

Schedule of Expected Amortization of the Intangible Assets

The expected amortization of the intangible assets, as of December 31, 2023, for each of the next five years and thereafter is as follows:


2024	$	4,903
2025		4,903
2026		4,903
2027		4,462
2028		4,022
Thereafter		14,078
Total	$	37,271