Voyager Therapeutics (VYGR) 10-Q 13 May 24 2024 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2024	May 08, 2024
Document and Entity Information
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Mar. 31, 2024
Entity File Number	001-37625
Entity Registrant Name	Voyager Therapeutics, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	46-3003182
Entity Address, Address Line One	75 Hayden Avenue
Entity Address, City or Town	Lexington
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02421
City Area Code	857
Local Phone Number	259-5340
Title of 12(b) Security	Common Stock, $0.001 par value
Trading Symbol	VYGR
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Central Index Key	0001640266
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Entity Common Stock, Shares Outstanding		54,393,628

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 143,078	$ 68,802
Marketable securities, current	256,490	162,073
Accounts receivable	837	80,150
Related party collaboration receivable	2,620	3,341
Prepaid expenses and other current assets	6,112	5,318
Total current assets	409,137	319,684
Property and equipment, net	17,381	16,494
Deposits and other non-current assets	2,890	1,593
Marketable securities, non-current	980
Operating lease, right-of-use assets	39,204	13,510
Total assets	469,592	351,281
Current liabilities:
Accounts payable	7,579	1,604
Accrued expenses	7,595	16,823
Other current liabilities	5,940	3,200
Deferred revenue, current	51,439	42,881
Total current liabilities	72,553	64,508
Deferred revenue, non-current	13,157	32,359
Other non-current liabilities	42,996	18,094
Total liabilities	128,706	114,961
Commitments and contingencies (see note 7)
Stockholders' equity:
Preferred stock, $0.001 par value: 5,000,000 shares authorized at March 31, 2024 and December 31, 2023; no shares issued and outstanding at March 31, 2024 and December 31, 2023
Common stock, $0.001 par value: 120,000,000 shares authorized at March 31, 2024 and December 31, 2023; 54,318,133 and 44,038,333 shares issued and outstanding at March 31, 2024 and December 31, 2023, respectively	54	44
Additional paid-in capital	613,850	497,506
Accumulated other comprehensive loss	(506)	(48)
Accumulated deficit	(272,512)	(261,182)
Total stockholders' equity	340,886	236,320
Total liabilities and stockholders' equity	$ 469,592	$ 351,281

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2024	Dec. 31, 2023
Condensed Consolidated Balance Sheets
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock shares authorized	120,000,000	120,000,000
Common stock shares issued	54,318,133	44,038,333
Common stock share outstanding	54,318,133	44,038,333

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive (Loss) Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Condensed Consolidated Statements of Operations and Comprehensive Income (Loss)
Collaboration revenue	$ 19,516	$ 150,480
Operating expenses:
Research and development	27,092	18,568
General and administrative	8,607	9,028
Total operating expenses	35,699	27,596
Operating (loss) income	(16,183)	122,884
Other income:
Interest income	4,867	1,864
Total other income	4,867	1,864
(Loss) income before income taxes	(11,316)	124,748
Income tax provision	14	704
Net (loss) income	(11,330)	124,044
Other comprehensive (loss) income:
Net unrealized (loss) gain on available-for-sale securities	(458)	87
Total other comprehensive (loss) income	(458)	87
Comprehensive (loss) income	$ (11,788)	$ 124,131
Net (loss) income per share, basic	$ (0.20)	$ 3.05
Net (loss) income per share, diluted	$ (0.20)	$ 2.94
Weighted-average common shares outstanding, basic	57,117,046	40,632,087
Weighted-average common shares outstanding, diluted	57,117,046	42,161,326

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common stock 2023 Neurocrine Collaborative Agreement	Common stock 2023 Novartis Collaboration Agreement	Common stock	Additional paid-in capital 2023 Neurocrine Collaborative Agreement	Additional paid-in capital 2023 Novartis Collaboration Agreement	Additional paid-in capital	Accumulated other comprehensive loss	Accumulated deficit	2023 Neurocrine Collaborative Agreement	2023 Novartis Collaboration Agreement	Total
Stockholders' Equity, Beginning Balance at Dec. 31, 2022			$ 38			$ 452,713	$ (219)	$ (393,512)			$ 59,020
Shares, Outstanding, Beginning Balance at Dec. 31, 2022			38,613,891
Exercises of vested stock options						185					185
Exercises of vested stock options (in shares)			51,993
Vesting of restricted stock units (in shares)			374,417
Issuance of common stock	$ 5			$ 31,116					$ 31,121
Issuance of common stock (in shares)	4,395,588
Stock based compensation expense						2,504					2,504
Unrealized gain (loss) on available-for-sale securities, net of tax							87				87
Net income (loss)								124,044			124,044
Stockholders' Equity, Ending Balance at Mar. 31, 2023			$ 43			486,518	(132)	(269,468)			216,961
Shares, Outstanding, Ending Balance at Mar. 31, 2023			43,435,889
Stockholders' Equity, Beginning Balance at Dec. 31, 2023			$ 44			497,506	(48)	(261,182)			236,320
Shares, Outstanding, Beginning Balance at Dec. 31, 2023			44,038,333
Exercises of vested stock options						78					$ 78
Exercises of vested stock options (in shares)			32,500								32,500
Vesting of restricted stock units (in shares)			324,520
Issuance of common stock		$ 2			$ 19,303					$ 19,305
Issuance of common stock (in shares)		2,145,002
Issuance of common stock and pre-funded warrants in connection with underwritten public offering			$ 8			93,465					$ 93,473
Issuance of common stock and pre-funded warrants in connection with underwritten public offering (in shares )			7,777,778
Stock based compensation expense						3,498					3,498
Unrealized gain (loss) on available-for-sale securities, net of tax							(458)				(458)
Net income (loss)								(11,330)			(11,330)
Stockholders' Equity, Ending Balance at Mar. 31, 2024			$ 54			$ 613,850	$ (506)	$ (272,512)			$ 340,886
Shares, Outstanding, Ending Balance at Mar. 31, 2024			54,318,133

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash flow from operating activities
Net (loss) income	$ (11,330)	$ 124,044
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Stock-based compensation expense	3,573	2,558
Depreciation	1,196	1,075
Amortization of premiums and discounts on marketable securities	(1,931)	(17)
Loss on disposal of fixed assets	59	44
Changes in operating assets and liabilities:
Accounts receivable	79,313	(25,000)
Related party collaboration receivable	721	(71)
Prepaid expenses and other current assets	(794)	1,411
Operating lease, right-of-use asset	1,057	469
Other non-current assets	(15)
Accounts payable	5,975	1,132
Accrued expenses	(9,305)	(122)
Operating lease liabilities	891	(683)
Deferred revenue	(10,643)	18,725
Net cash provided by operating activities	58,767	123,565
Cash flow from investing activities
Purchases of property and equipment	(2,141)	(509)
Purchases of marketable securities	(203,852)
Proceeds from sales and maturities of marketable securities	109,928	15,000
Net cash (used in) provided by investing activities	(96,065)	14,491
Cash flow from financing activities
Proceeds from the exercise of stock options	78	185
Proceeds from the issuance of common stock in connection with the underwritten public offering	93,473
Proceeds from the issuance of common stock in connection with the 2023 Novartis Stock Purchase Agreement	19,305
Proceeds from the issuance of common stock in connection with the 2023 Neurocrine Collaboration Agreement		31,121
Net cash provided by financing activities	112,856	31,306
Net increase in cash, cash equivalents, and restricted cash	75,558	169,362
Cash, cash equivalents, and restricted cash, beginning of period	70,395	100,474
Cash, cash equivalents, and restricted cash, end of period	145,953	269,836
Supplemental disclosure of cash and non-cash activities
Capital expenditures incurred but not yet paid		$ 109
Operating lease right-of-use assets obtained in exchange for operating lease liabilities	$ 26,751

Nature of business

Nature of business	3 Months Ended
	Mar. 31, 2024
Nature of business
Nature of business	1. Nature of business Voyager Therapeutics, Inc. (the “Company”) is a biotechnology company whose mission is to leverage the power of human genetics to modify the course of and ultimately cure neurological diseases. The Company’s pipeline includes programs for Alzheimer’s disease; amyotrophic lateral sclerosis; Parkinson’s disease, and multiple other diseases of the central nervous system. Many of the Company’s programs are derived from its TRACER™ adeno-associated virus (“AAV”) capsid discovery platform, which the Company has used to generate novel capsids (“TRACER Capsids”) and identify associated receptors to potentially enable high brain penetration with genetic medicines following intravenous dosing. Some of the Company’s programs are wholly-owned, and some are advancing with licensees and collaborators including Alexion, AstraZeneca Rare Disease; Novartis Pharma AG, (“Novartis”); and Neurocrine Biosciences, Inc. (“Neurocrine”). The Company has a history of incurring annual net operating losses. As of March 31, 2024, the Company had an accumulated deficit of $272.5 million. The Company has not generated any product revenue and has financed its operations primarily through public offerings and private placements of its equity securities, funding from fees, option exercise payments, and milestone payments, and cost reimbursements associated with its prior and ongoing collaborations and license agreements. ​ As of March 31, 2024, the Company had cash, cash equivalents, and marketable securities of $400.5 million. Based upon the Company’s current operating plans, the Company expects that its existing cash, cash equivalents, and marketable securities at March 31, 2024 to be sufficient to meet the Company’s planned operating expenses and capital expenditure requirements for at least twelve months from the issuance of these consolidated financial statements. ​ There can be no assurance that the Company will be able to obtain additional debt or equity financing on terms acceptable to the Company or generate product revenue or revenue from collaboration partners, on a timely basis or at all. The failure of the Company to obtain sufficient funds on acceptable terms when needed could have a material adverse effect on the Company’s business, results of operations, and financial condition. ​

Summary of significant accounti

Summary of significant accounting policies and basis of presentation	3 Months Ended
	Mar. 31, 2024
Summary of significant accounting policies and basis of presentation
Summary of significant accounting policies and basis of presentation	2. Summary of significant accounting policies and basis of presentation Basis of Presentation The accompanying unaudited condensed consolidated financial statements of the Company have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) for interim financial reporting. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. For further information, refer to the consolidated financial statements and footnotes included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2023 as filed with the Securities and Exchange Commission (“SEC”) on February 28, 2024. These interim condensed consolidated financial statements, in the opinion of management, reflect all normal recurring adjustments necessary for a fair presentation of the Company’s financial position and results of operations for the periods presented. Any reference in these notes to applicable guidance is meant to refer to the authoritative United States generally accepted accounting principles as found in the Accounting Standards Codification and Accounting Standards Updates of the Financial Accounting Standards Board. Principles of Consolidation The unaudited interim consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary as disclosed in Note 2, under the heading “Summary of Significant Accounting Policies and Basis of Presentation” within the “Notes to Consolidated Financial Statements” accompanying the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2023. Intercompany balances and transactions have been eliminated. Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. On an ongoing basis, the Company’s management evaluates its estimates, which include, but are not limited to, estimates related to revenue recognition, incremental borrowing rate for leases, accrued expenses, stock-based compensation expense, and income taxes. The Company bases its estimates on historical experience and other market-specific or other relevant assumptions that it believes to be reasonable under the circumstances. Actual results may differ from those estimates or assumptions. Summary of Significant Accounting Policies There have been no changes in the Company's significant accounting policies as described in Note 2, “Summary of Significant Accounting Policies and Basis of Presentation” within the “Notes to Consolidated Financial Statements” accompanying the Company’s Annual Report on Form 10-K for the year ended December 31, 2023.

Fair value measurements

Fair value measurements	3 Months Ended
	Mar. 31, 2024
Fair value measurements
Fair value measurements	3. Fair value measurements Assets and liabilities measured at fair value on a recurring basis as of March 31, 2024 and December 31, 2023 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Quoted Prices ​ Significant ​ ​ ​ ​ ​ ​ ​ ​ in Active ​ Other ​ Significant ​ ​ ​ ​ ​ Markets for ​ Observable ​ Unobservable ​ ​ ​ ​ ​ Identical Assets ​ Inputs ​ Inputs ​ Assets Total (Level 1) (Level 2) (Level 3) March 31, 2024 ​ (in thousands) Money market funds included in cash and cash equivalents $ 49,444 $ 49,444 $ — $ — ​ Marketable securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Treasury notes ​ ​ 24,486 ​ ​ 24,486 ​ ​ — ​ ​ — ​ U.S. Government agency securities ​ ​ 138,191 ​ ​ 138,191 ​ ​ — ​ ​ — ​ Corporate bonds ​ ​ 88,983 ​ ​ — ​ ​ 88,983 ​ ​ — ​ Commercial paper ​ ​ 4,830 ​ ​ — ​ ​ 4,830 ​ ​ — ​ Total money market funds and marketable securities ​ $ 305,934 ​ $ 212,121 ​ $ 93,813 ​ $ — ​ December 31, 2023 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds included in cash and cash equivalents $ 65,589 ​ $ 65,589 ​ $ — ​ $ — ​ Marketable securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Treasury notes ​ ​ 103,044 ​ ​ 103,044 ​ ​ — ​ ​ — ​ U.S. Government agency securities ​ ​ 31,075 ​ ​ 31,075 ​ ​ — ​ ​ — ​ Corporate bonds ​ ​ 23,970 ​ ​ — ​ ​ 23,970 ​ ​ — ​ Commercial paper ​ ​ 3,985 ​ ​ — ​ ​ 3,985 ​ ​ — ​ Total money market funds and marketable securities ​ $ 227,663 ​ $ 199,708 ​ $ 27,955 ​ $ — ​ ​ The Company measures the fair value of money market funds, U.S. Treasury notes, and U.S. Government agency securities based on quoted prices in active markets for identical securities. The Company measures the fair value of the Level 2 securities, corporate bonds and commercial paper, based on recent trades of securities in active markets or based on quoted market prices of similar instruments and other significant inputs derived from or corroborated by observable market data.

Cash, cash equivalents, restric

Cash, cash equivalents, restricted cash, and available-for-sale marketable securities	3 Months Ended
	Mar. 31, 2024
Cash, cash equivalents, restricted cash, and available-for-sale marketable securities
Cash, cash equivalents, restricted cash, and available-for-sale marketable securities	4. Cash, cash equivalents, restricted cash, and available-for-sale marketable securities Cash, cash equivalents, and marketable securities included the following at March 31, 2024 and December 31, 2023: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Fair ​ ​ Cost Gains Losses Value ​ ​ ​ (in thousands) ​ As of March 31, 2024 ​ ​ ​ ​ ​ Money market funds included in cash and cash equivalents ​ $ 49,444 ​ $ — ​ $ — ​ $ 49,444 ​ Marketable securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Treasury notes ​ ​ 24,540 ​ ​ — ​ ​ (54) ​ ​ 24,486 ​ U.S. Government agency securities ​ ​ 138,285 ​ ​ 7 ​ ​ (101) ​ ​ 138,191 ​ Corporate bonds ​ ​ 89,207 ​ ​ 11 ​ ​ (235) ​ ​ 88,983 ​ Commercial paper ​ ​ 4,829 ​ ​ 1 ​ ​ — ​ ​ 4,830 ​ Total money market funds and marketable securities ​ $ 306,305 ​ $ 19 ​ $ (390) ​ $ 305,934 ​ As of December 31, 2023 ​ ​ ​ ​ ​ Money market funds included in cash and cash equivalents ​ $ 65,589 ​ ​ — ​ ​ — ​ $ 65,589 ​ Marketable securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Treasury notes ​ ​ 102,966 ​ ​ 81 ​ ​ (3) ​ ​ 103,044 ​ U.S. Government agency securities ​ ​ 31,068 ​ ​ 10 ​ ​ (3) ​ ​ 31,075 ​ Corporate bonds ​ ​ 23,975 ​ ​ 2 ​ ​ (7) ​ ​ 23,970 ​ Commercial paper ​ ​ 3,985 ​ ​ — ​ ​ — ​ 3,985 ​ Total money market funds and marketable securities ​ $ 227,583 ​ $ 93 ​ $ (13) ​ $ 227,663 ​ ​ The Company had $1.0 million in marketable securities as of March 31, 2024 with a contractual maturity of greater than one year. All other marketable securities have a contractual maturity of one year or less. The Company reviews investments whenever the fair value of an investment is less than the amortized cost and evidence indicates that an investment’s carrying amount is not recoverable within a reasonable period of time. In connection with these investments, the Company evaluates whether the decline in fair value has resulted from credit losses or other factors, considering the extent to which fair value is less than amortized cost, any changes to the rating of the security by a rating agency, and adverse conditions specifically related to the security, among other factors. If this assessment indicates that a credit loss exists, the present value of cash flows expected to be collected from the security is compared to the amortized cost basis of the security. If the present value of cash flows expected to be collected is less than the amortized cost basis, a credit loss exists and an allowance for credit losses is recorded for the credit loss on the condensed consolidated balance sheet, limited by the amount that the fair value is less than the amortized cost basis. Any impairment that is not related to credit is recognized in other comprehensive loss. Changes in the allowance for credit losses are recorded as a provision for (or reversal of) credit loss expense in general and administrative expenses within the condensed consolidated statement of operations. Losses are charged against the allowance when the Company believes the uncollectability of an available-for-sale security is confirmed or when either of the criteria regarding intent or requirement to sell is met. The Company held $230.7 million and $44.2 million marketable securities that were in an unrealized loss position as of March 31, 2024 and December 31, 2023, respectively. The unrealized losses at March 31, 2024 and December 31, 2023 were attributable to changes in interest rates and do not represent credit losses. The Company does not intend to sell these securities and it is not more likely than not that it will be required to sell them before recovery of their amortized cost basis. The following table provides a reconciliation of cash, cash equivalents, and restricted cash within the condensed consolidated balance sheets that sum to the total of the same such amounts shown in the condensed consolidated statements of cash flows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, ​ ​ 2024 2023 ​ ​ (in thousands) Cash and cash equivalents ​ $ 143,078 ​ $ 268,321 Restricted cash included in deposits and other non-current assets ​ ​ 2,875 ​ ​ 1,515 Total cash, cash equivalents, and restricted cash ​ $ 145,953 ​ $ 269,836 ​

Accrued expenses

Accrued expenses	3 Months Ended
	Mar. 31, 2024
Accrued expenses
Accrued expenses	5. Accrued expenses Accrued expenses as of March 31, 2024 and December 31, 2023 consist of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, ​ As of December 31, ​ 2024 2023 ​ ​ (in thousands) Research and development costs ​ $ 2,914 ​ $ 5,225 Employee compensation costs ​ 2,248 ​ 6,614 Accrued goods and services ​ 1,838 ​ 4,229 Professional services ​ ​ 595 ​ ​ 755 Total ​ $ 7,595 ​ $ 16,823 ​

Lease obligation

Lease obligation	3 Months Ended
	Mar. 31, 2024
Lease obligation
Lease obligation	6. Lease obligation Operating Leases As of March 31, 2024, the Company has a lease for laboratory and office space at 75 Hayden Avenue in Lexington, Massachusetts through January 31, 2031 and a lease for additional office and laboratory space at 64 Sidney Street in Cambridge, Massachusetts through November 30, 2026. On August 11, 2023, the Company entered into a first amendment (the “First Amendment”) to its existing lease for laboratory and office space at 75 Hayden Avenue in Lexington, Massachusetts, pursuant to which the Company agreed to lease approximately 61,307 square feet of additional office and laboratory space through January 31, 2031. The Company received $1.8 million of leasehold improvement incentives associated with the First Amendment. The Company gained control of the space on February 1, 2024 and recorded a $26.7 million right-of-use asset and a $26.7 million operating lease liability, accordingly, which reflect the leasehold improvement incentive. The Company’s lease agreements require the Company to maintain a cash deposit or irrevocable letter of credit in the aggregate amount of $2.9 million payable to its landlords as security for the performance of its obligations under the leases. These amounts are recorded as restricted cash and are included in deposits and other non-current assets in the accompanying condensed consolidated balance sheets. During the three months ended March 31, 2024 and 2023, the Company incurred lease expenses of $1.7 million and $0.9 million, respectively, for operating leases. As of March 31, 2024, the weighted average remaining lease term was 5.5 years and the weighted average incremental borrowing rate used to determine the operating lease liability was 6.9%. ​ ​

Commitments, contingencies and

Commitments, contingencies and other liabilities	3 Months Ended
	Mar. 31, 2024
Commitments, contingencies and other liabilities
Commitments, contingencies and other liabilities	7. Commitments, contingencies and other liabilities ​ As of March 31, 2024 and December 31, 2023, other current and non-current liabilities consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, ​ As of December 31, ​ ​ 2024 ​ 2023 ​ ​ (in thousands) ​ Other current liabilities ​ ​ ​ ​ ​ ​ Lease liability ​ 5,940 ​ ​ 3,200 ​ Total other current liabilities $ 5,940 ​ $ 3,200 ​ ​ ​ ​ ​ ​ ​ ​ Other non-current liabilities ​ ​ ​ ​ ​ ​ Lease liability $ 41,995 ​ $ 17,093 ​ Other ​ 1,001 ​ ​ 1,001 ​ Total other non-current liabilities $ 42,996 ​ $ 18,094 ​ ​ Other Agreements ​ In 2016, the Company entered into a research and development funding arrangement with a non-profit organization that provides up to $4.0 million in funding to the Company upon the achievement of clinical and development milestones. The agreement provides that the Company repay amounts received under certain circumstances including termination of the agreement, and to pay an amount up to 2.6 times the funding received upon successful development and commercialization of any products developed. In 2017, the Company earned a milestone payment of $1.0 million. The Company evaluated the arrangement and concluded that it represents a research and development financing arrangement as it is probable that the Company will repay amounts received under the arrangement. As a result, the $1.0 million is recorded as a non-current liability in the condensed consolidated balance sheet. Litigation The Company was not a party to any material legal matters or claims as of March 31, 2024, or December 31, 2023. The Company did not have contingency reserves established for any litigation liabilities as of March 31, 2024, or December 31, 2023.

Significant agreements

Significant agreements	3 Months Ended
	Mar. 31, 2024
Significant agreements
Significant agreements	​ 8. Significant agreements ​ ​ 2023 Neurocrine Collaboration Agreement ​ ​ 2023 Novartis Stock Purchase Agreement ​ Under the stock purchase agreement entered into in December 2023 (the “2023 Novartis Stock Purchase Agreement”), Novartis purchased 2,145,002 shares of common stock of the Company (the “Novartis Shares”) for an aggregate purchase price of approximately $20.0 million. The issuance of the Novartis Shares to Novartis pursuant to the 2023 Novartis Stock Purchase Agreement in January 2024 resulted in a premium of $0.7 million. The premium was allocated to the development and commercialization licenses granted to Novartis for two programs pursuant to the license and collaboration agreement with Novartis entered into in December 2023 and was recognized as collaboration revenue during the first quarter of 2024, upon the issuance of the Novartis Shares under the 2023 Novartis Stock Purchase Agreement. ​ 2019 Neurocrine Collaboration Agreement ​ In February 2024, the Company announced that the joint steering committee with Neurocine selected a lead development candidate for the gene therapy program for Friedreich’s ataxia (the “FA Program”) under the collaboration and license agreement with Neurocrine entered into in January 2019 (the “2019 Neurocrine Collaboration Agreement”), which triggered a $5.0 million milestone payment to the Company that was received in the first quarter of 2024. The Company included the $5.0 million that had previously been constrained in the transaction price allocated to the FA performance obligation in the three months ended March 31, 2024, accordingly, which resulted in a cumulative catch-up adjustment to collaboration revenue of $4.4 million. ​ Related Party Collaboration Receivable ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at ​ ​ ​ ​ Balance at ​ ​ ​ December 31, 2023 ​ Additions ​ Deductions ​ March 31, 2024 ​ ​ ​ ​ ( in thousands) ​ Related party collaboration receivables ​ $ 3,341 ​ $ 7,340 ​ $ (8,061) ​ $ 2,620 ​ Contract liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Deferred revenue ​ $ 75,240 ​ $ 586 ​ $ (11,230) ​ $ 64,596 ​ ​

Stock-based compensation

Stock-based compensation	3 Months Ended
	Mar. 31, 2024
Stock-based compensation
Stock-based compensation	9. Stock-based compensation Stock-Based Compensation Expense Total compensation cost recognized for all stock-based compensation awards in the condensed consolidated statements of operations and comprehensive (loss) income was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ March 31, ​ 2024 2023 ​ ​ (in thousands) ​ Research and development ​ $ 1,280 ​ $ 863 ​ General and administrative ​ 2,293 ​ 1,695 ​ Total stock-based compensation expense ​ $ 3,573 ​ $ 2,558 ​ ​ Stock-based compensation expense by type of award included within the condensed consolidated statements of operations and comprehensive (loss) income was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ March 31, ​ ​ 2024 2023 ​ ​ ​ (in thousands) ​ Stock options ​ $ 2,408 ​ $ 1,663 ​ Restricted stock awards and units ​ ​ 1,090 ​ ​ 841 ​ Employee stock purchase plan awards ​ 75 ​ 54 ​ Total stock-based compensation expense ​ $ 3,573 ​ $ 2,558 ​ ​ Restricted Stock Units A summary of the status of and changes in unvested restricted stock unit activity under the Company’s equity award plans for the three months ended March 31, 2024 was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ Average ​ ​ ​ ​ ​ Grant Date ​ ​ ​ ​ ​ Fair Value ​ ​ Units Per Unit ​ Unvested restricted stock units as of December 31, 2023 1,370,897 ​ $ 6.65 ​ Granted 696,908 ​ $ 7.63 ​ Vested (324,520) ​ $ 5.75 ​ Forfeited (23,947) ​ $ 6.42 ​ Unvested restricted stock units as of March 31, 2024 1,719,338 ​ $ 7.22 ​ ​ Stock-based compensation of restricted stock units is based on the fair value of the Company’s common stock on the date of grant and is recognized over the vesting period. Restricted stock units granted by the Company typically vest in equal amounts, annually over three years. All of the restricted stock units granted in the three months ended March 31, 2024 vest in equal amounts, annually over three years. The stock-based compensation expense related to restricted stock units and awards was $1.1 million and $0.8 million for the three months ended March 31, 2024 and 2023, respectively. As of March 31, 2024, the Company had unrecognized stock-based compensation expense related to its unvested restricted stock units of $10.9 million, which is expected to be recognized over the remaining average vesting period of 2.4 years. Stock Options The following is a summary of stock option activity for the three months ended March 31, 2024: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted Remaining Aggregate ​ ​ ​ ​ ​ Average ​ Contractual ​ Intrinsic ​ ​ ​ ​ ​ Exercise ​ Life ​ Value ​ ​ Shares Price (in years) (in thousands) ​ Outstanding at December 31, 2023 7,425,444 ​ $ 8.52 ​ ​ ​ ​ ​ ​ Granted 1,747,626 ​ $ 7.68 ​ ​ ​ ​ ​ ​ Exercised (32,500) ​ $ 4.91 ​ ​ ​ ​ ​ ​ Cancelled or forfeited (230,974) ​ $ 12.28 ​ ​ ​ ​ ​ ​ Outstanding at March 31, 2024 8,909,596 ​ $ 8.27 ​ 7.8 ​ $ 17,875 ​ Exercisable at March 31, 2024 3,880,357 ​ $ 9.04 ​ 6.2 ​ $ 8,728 ​ ​ As of March 31, 2024, the Company had unrecognized stock-based compensation expense related to its unvested stock options of $23.2 million which is expected to be recognized over the remaining weighted-average vesting period of 3.0 years.

Net (loss) income per share

Net (loss) income per share	3 Months Ended
	Mar. 31, 2024
Net (loss) income per share
Net (loss) income per share	10. Net (loss) income per share The following table sets forth the outstanding potentially dilutive securities that have been excluded in the calculation of diluted net (loss) income per share because to include them would be anti-dilutive: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, ​ ​ ​ 2024 ​ 2023 ​ Unvested restricted common stock awards ​ 22,500 ​ 45,000 ​ Unvested restricted common stock units ​ ​ 1,719,338 ​ ​ 1,336,159 ​ Outstanding stock options ​ 8,909,596 ​ 7,360,745 ​ Total ​ 10,651,434 ​ 8,741,904 ​ ​ Basic net (loss) income and diluted weighted-average shares outstanding are as follows for the three months ended March 31, 2024 and 2023: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ ​ ​ 2024 ​ 2023 ​ ​ ​ ​ ​ Numerator: ​ ​ ​ ​ ​ ​ ​ Net (loss) income (in thousands) ​ $ (11,330) ​ $ 124,044 ​ Denominator for basic net (loss) income per share: ​ ​ ​ ​ ​ ​ ​ Weighted average shares outstanding-basic ​ ​ 57,117,046 ​ ​ 40,632,087 ​ Denominator for diluted net (loss) income per share: ​ ​ ​ ​ ​ ​ ​ Weighted average shares outstanding-basic ​ ​ 57,117,046 ​ ​ 40,632,087 ​ Common stock options and restricted stock units ​ ​ — ​ ​ 1,529,239 ​ Weighted average shares outstanding-diluted ​ ​ 57,117,046 ​ ​ 42,161,326 ​ ​ ​ ​ ​ ​ ​ ​ ​ Net (loss) income per share, basic: ​ $ (0.20) ​ $ 3.05 ​ Net (loss) income per share, diluted: ​ $ (0.20) ​ $ 2.94 ​ ​ ​ ​ ​ ​ ​ ​ ​ The pre ghted average shares outstanding for the three months ended March 31, 2024.

Underwritten public offering

Underwritten public offering	3 Months Ended
	Mar. 31, 2024
Underwritten public offering
Underwritten public offering	11. Underwritten public offering ​ On January 4, 2024, the Company entered into an underwriting agreement (the “Underwriting Agreement”) with Citigroup Global Markets Inc. and Guggenheim Securities, LLC, as representatives of the several underwriters named therein (the “Underwriters”), relating to an underwritten public offering of 7,777,778 shares of the Company’s common stock, par value $0.001 per share, and, in lieu of common stock to certain investors, pre-funded warrants (the “Pre-Funded Warrants”) to purchase up to 3,333,333 shares of common stock. The Underwriters agreed to purchase the Company’s stock from the Company pursuant to the Underwriting Agreement at a price of $8.46 and the Pre-Funded Warrants from the Company pursuant to the Underwriting Agreement at a price of $8.459 per share underlying each Pre-Funded Warrant. Under the terms of the Underwriting Agreement, the Company also granted the Underwriters an option, exercisable for 30 days , to purchase up to an additional 1,666,665 shares of common stock at the public offering price less the underwriting discounts and commissions. This option was not exercised and expired on February 2, 2024. ​ offering expenses pursuant to the underwritten public offering. The Pre-Funded Warrants met the equity classification guidance and therefore are classified as stockholders’ equity. ​

Related party transactions

Related party transactions	3 Months Ended
	Mar. 31, 2024
Related party transactions
Related party transactions	12. Related-party transactions During the three months ended March 31, 2024, the Company received scientific advisory board and other scientific advisory services from one of its prior executives, Dinah Sah, Ph.D., the Company’s former Chief Scientific Officer. The total amount of fees paid to Dr. Sah for services provided during the three months ended March 31, 2024 and 2023, was $150,000 and $199,800, respectively. Under each of the Company’s collaboration agreements with Neurocrine, the Company and Neurocrine have agreed to conduct research, development, and commercialization activities for certain of the Company’s AAV gene therapy product candidates. Amounts due from Neurocrine are reflected as related party collaboration receivables. As of March 31, 2024, the Company had approximately $1.2 million and $1.4 million in related party collaboration receivables associated with the 2019 Neurocrine Collaboration Agreement and 2023 Neurocrine Collaboration Agreement, respectively.

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2024
Subsequent Events
Subsequent Events	13. Subsequent Events ​ In April 2024, the Company announced that the joint steering committee with Neurocrine selected a development candidate for the glucocerebrosidase 1 gene therapy program for Parkinson’s disease and other GBA1-mediated diseases under the 2023 Neurocrine Collaboration Agreement (the “GBA1 program”). The joint steering committee selection of a development candidate for the GBA1 Program triggered a $3.0 million milestone payment to the Company. The Company expects to receive the $3.0 million during the second quarter of 2024. ​

Summary of significant accoun_2

Summary of significant accounting policies and basis of presentation (Policies)	3 Months Ended
	Mar. 31, 2024
Summary of significant accounting policies and basis of presentation
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements of the Company have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) for interim financial reporting. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. For further information, refer to the consolidated financial statements and footnotes included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2023 as filed with the Securities and Exchange Commission (“SEC”) on February 28, 2024. These interim condensed consolidated financial statements, in the opinion of management, reflect all normal recurring adjustments necessary for a fair presentation of the Company’s financial position and results of operations for the periods presented. Any reference in these notes to applicable guidance is meant to refer to the authoritative United States generally accepted accounting principles as found in the Accounting Standards Codification and Accounting Standards Updates of the Financial Accounting Standards Board.
Principles of Consolidation	Principles of Consolidation The unaudited interim consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary as disclosed in Note 2, under the heading “Summary of Significant Accounting Policies and Basis of Presentation” within the “Notes to Consolidated Financial Statements” accompanying the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2023. Intercompany balances and transactions have been eliminated.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. On an ongoing basis, the Company’s management evaluates its estimates, which include, but are not limited to, estimates related to revenue recognition, incremental borrowing rate for leases, accrued expenses, stock-based compensation expense, and income taxes. The Company bases its estimates on historical experience and other market-specific or other relevant assumptions that it believes to be reasonable under the circumstances. Actual results may differ from those estimates or assumptions.
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies There have been no changes in the Company's significant accounting policies as described in Note 2, “Summary of Significant Accounting Policies and Basis of Presentation” within the “Notes to Consolidated Financial Statements” accompanying the Company’s Annual Report on Form 10-K for the year ended December 31, 2023.

Fair value measurements (Tables

Fair value measurements (Tables)	3 Months Ended
	Mar. 31, 2024
Fair value measurements
Schedule of assets and liabilities measured at fair value on a recurring basis	Assets and liabilities measured at fair value on a recurring basis as of March 31, 2024 and December 31, 2023 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Quoted Prices ​ Significant ​ ​ ​ ​ ​ ​ ​ ​ in Active ​ Other ​ Significant ​ ​ ​ ​ ​ Markets for ​ Observable ​ Unobservable ​ ​ ​ ​ ​ Identical Assets ​ Inputs ​ Inputs ​ Assets Total (Level 1) (Level 2) (Level 3) March 31, 2024 ​ (in thousands) Money market funds included in cash and cash equivalents $ 49,444 $ 49,444 $ — $ — ​ Marketable securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Treasury notes ​ ​ 24,486 ​ ​ 24,486 ​ ​ — ​ ​ — ​ U.S. Government agency securities ​ ​ 138,191 ​ ​ 138,191 ​ ​ — ​ ​ — ​ Corporate bonds ​ ​ 88,983 ​ ​ — ​ ​ 88,983 ​ ​ — ​ Commercial paper ​ ​ 4,830 ​ ​ — ​ ​ 4,830 ​ ​ — ​ Total money market funds and marketable securities ​ $ 305,934 ​ $ 212,121 ​ $ 93,813 ​ $ — ​ December 31, 2023 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds included in cash and cash equivalents $ 65,589 ​ $ 65,589 ​ $ — ​ $ — ​ Marketable securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Treasury notes ​ ​ 103,044 ​ ​ 103,044 ​ ​ — ​ ​ — ​ U.S. Government agency securities ​ ​ 31,075 ​ ​ 31,075 ​ ​ — ​ ​ — ​ Corporate bonds ​ ​ 23,970 ​ ​ — ​ ​ 23,970 ​ ​ — ​ Commercial paper ​ ​ 3,985 ​ ​ — ​ ​ 3,985 ​ ​ — ​ Total money market funds and marketable securities ​ $ 227,663 ​ $ 199,708 ​ $ 27,955 ​ $ — ​

Cash, cash equivalents, restr_2

Cash, cash equivalents, restricted cash, and available-for-sale marketable securities (Tables)	3 Months Ended
	Mar. 31, 2024
Cash, cash equivalents, restricted cash, and available-for-sale marketable securities
Schedule of money market funds and marketable securities	Cash, cash equivalents, and marketable securities included the following at March 31, 2024 and December 31, 2023: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Fair ​ ​ Cost Gains Losses Value ​ ​ ​ (in thousands) ​ As of March 31, 2024 ​ ​ ​ ​ ​ Money market funds included in cash and cash equivalents ​ $ 49,444 ​ $ — ​ $ — ​ $ 49,444 ​ Marketable securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Treasury notes ​ ​ 24,540 ​ ​ — ​ ​ (54) ​ ​ 24,486 ​ U.S. Government agency securities ​ ​ 138,285 ​ ​ 7 ​ ​ (101) ​ ​ 138,191 ​ Corporate bonds ​ ​ 89,207 ​ ​ 11 ​ ​ (235) ​ ​ 88,983 ​ Commercial paper ​ ​ 4,829 ​ ​ 1 ​ ​ — ​ ​ 4,830 ​ Total money market funds and marketable securities ​ $ 306,305 ​ $ 19 ​ $ (390) ​ $ 305,934 ​ As of December 31, 2023 ​ ​ ​ ​ ​ Money market funds included in cash and cash equivalents ​ $ 65,589 ​ ​ — ​ ​ — ​ $ 65,589 ​ Marketable securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Treasury notes ​ ​ 102,966 ​ ​ 81 ​ ​ (3) ​ ​ 103,044 ​ U.S. Government agency securities ​ ​ 31,068 ​ ​ 10 ​ ​ (3) ​ ​ 31,075 ​ Corporate bonds ​ ​ 23,975 ​ ​ 2 ​ ​ (7) ​ ​ 23,970 ​ Commercial paper ​ ​ 3,985 ​ ​ — ​ ​ — ​ 3,985 ​ Total money market funds and marketable securities ​ $ 227,583 ​ $ 93 ​ $ (13) ​ $ 227,663 ​
Reconciliation of cash, cash equivalents, and restricted cash	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, ​ ​ 2024 2023 ​ ​ (in thousands) Cash and cash equivalents ​ $ 143,078 ​ $ 268,321 Restricted cash included in deposits and other non-current assets ​ ​ 2,875 ​ ​ 1,515 Total cash, cash equivalents, and restricted cash ​ $ 145,953 ​ $ 269,836 ​

Accrued expenses (Tables)

Accrued expenses (Tables)	3 Months Ended
	Mar. 31, 2024
Accrued expenses
Schedule of accrued expenses	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, ​ As of December 31, ​ 2024 2023 ​ ​ (in thousands) Research and development costs ​ $ 2,914 ​ $ 5,225 Employee compensation costs ​ 2,248 ​ 6,614 Accrued goods and services ​ 1,838 ​ 4,229 Professional services ​ ​ 595 ​ ​ 755 Total ​ $ 7,595 ​ $ 16,823 ​

Commitments, contingencies an_2

Commitments, contingencies and other liabilities (Tables)	3 Months Ended
	Mar. 31, 2024
Commitments, contingencies and other liabilities
Summary of other current and non-current liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, ​ As of December 31, ​ ​ 2024 ​ 2023 ​ ​ (in thousands) ​ Other current liabilities ​ ​ ​ ​ ​ ​ Lease liability ​ 5,940 ​ ​ 3,200 ​ Total other current liabilities $ 5,940 ​ $ 3,200 ​ ​ ​ ​ ​ ​ ​ ​ Other non-current liabilities ​ ​ ​ ​ ​ ​ Lease liability $ 41,995 ​ $ 17,093 ​ Other ​ 1,001 ​ ​ 1,001 ​ Total other non-current liabilities $ 42,996 ​ $ 18,094 ​

Significant agreements (Tables)

Significant agreements (Tables)	3 Months Ended
	Mar. 31, 2024
2023 Neurocrine Collaborative Agreement and 2019 Neurocrine Collaborative Agreement
Schedule of collaboration receivables and contract liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at ​ ​ ​ ​ Balance at ​ ​ ​ December 31, 2023 ​ Additions ​ Deductions ​ March 31, 2024 ​ ​ ​ ​ ( in thousands) ​ Related party collaboration receivables ​ $ 3,341 ​ $ 7,340 ​ $ (8,061) ​ $ 2,620 ​ Contract liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Deferred revenue ​ $ 75,240 ​ $ 586 ​ $ (11,230) ​ $ 64,596 ​

Stock-based compensation (Table

Stock-based compensation (Tables)	3 Months Ended
	Mar. 31, 2024
Stock-based compensation
Compensation cost recognized for all stock-based compensation awards	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ March 31, ​ 2024 2023 ​ ​ (in thousands) ​ Research and development ​ $ 1,280 ​ $ 863 ​ General and administrative ​ 2,293 ​ 1,695 ​ Total stock-based compensation expense ​ $ 3,573 ​ $ 2,558 ​
Summary of stock-based compensation expense by type of award	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ ​ March 31, ​ ​ 2024 2023 ​ ​ ​ (in thousands) ​ Stock options ​ $ 2,408 ​ $ 1,663 ​ Restricted stock awards and units ​ ​ 1,090 ​ ​ 841 ​ Employee stock purchase plan awards ​ 75 ​ 54 ​ Total stock-based compensation expense ​ $ 3,573 ​ $ 2,558 ​
Summary of status and changes in unvested restricted stock	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ Average ​ ​ ​ ​ ​ Grant Date ​ ​ ​ ​ ​ Fair Value ​ ​ Units Per Unit ​ Unvested restricted stock units as of December 31, 2023 1,370,897 ​ $ 6.65 ​ Granted 696,908 ​ $ 7.63 ​ Vested (324,520) ​ $ 5.75 ​ Forfeited (23,947) ​ $ 6.42 ​ Unvested restricted stock units as of March 31, 2024 1,719,338 ​ $ 7.22 ​
Summary of stock option activity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted Remaining Aggregate ​ ​ ​ ​ ​ Average ​ Contractual ​ Intrinsic ​ ​ ​ ​ ​ Exercise ​ Life ​ Value ​ ​ Shares Price (in years) (in thousands) ​ Outstanding at December 31, 2023 7,425,444 ​ $ 8.52 ​ ​ ​ ​ ​ ​ Granted 1,747,626 ​ $ 7.68 ​ ​ ​ ​ ​ ​ Exercised (32,500) ​ $ 4.91 ​ ​ ​ ​ ​ ​ Cancelled or forfeited (230,974) ​ $ 12.28 ​ ​ ​ ​ ​ ​ Outstanding at March 31, 2024 8,909,596 ​ $ 8.27 ​ 7.8 ​ $ 17,875 ​ Exercisable at March 31, 2024 3,880,357 ​ $ 9.04 ​ 6.2 ​ $ 8,728 ​

Net (loss) income per share (Ta

Net (loss) income per share (Tables)	3 Months Ended
	Mar. 31, 2024
Net (loss) income per share
Outstanding potentially dilutive securities excluded in the calculation of diluted net (loss) income per share	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, ​ ​ ​ 2024 ​ 2023 ​ Unvested restricted common stock awards ​ 22,500 ​ 45,000 ​ Unvested restricted common stock units ​ ​ 1,719,338 ​ ​ 1,336,159 ​ Outstanding stock options ​ 8,909,596 ​ 7,360,745 ​ Total ​ 10,651,434 ​ 8,741,904 ​
Schedule of weighted average number of shares, basic and diluted	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ ​ ​ 2024 ​ 2023 ​ ​ ​ ​ ​ Numerator: ​ ​ ​ ​ ​ ​ ​ Net (loss) income (in thousands) ​ $ (11,330) ​ $ 124,044 ​ Denominator for basic net (loss) income per share: ​ ​ ​ ​ ​ ​ ​ Weighted average shares outstanding-basic ​ ​ 57,117,046 ​ ​ 40,632,087 ​ Denominator for diluted net (loss) income per share: ​ ​ ​ ​ ​ ​ ​ Weighted average shares outstanding-basic ​ ​ 57,117,046 ​ ​ 40,632,087 ​ Common stock options and restricted stock units ​ ​ — ​ ​ 1,529,239 ​ Weighted average shares outstanding-diluted ​ ​ 57,117,046 ​ ​ 42,161,326 ​ ​ ​ ​ ​ ​ ​ ​ ​ Net (loss) income per share, basic: ​ $ (0.20) ​ $ 3.05 ​ Net (loss) income per share, diluted: ​ $ (0.20) ​ $ 2.94 ​

Nature of business (Details)

Nature of business (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Nature of business
Accumulated deficit	$ (272,512)	$ (261,182)
Cash, cash equivalents, and marketable debt securities	$ 400,500

Fair value measurements - Asset

Fair value measurements - Assets and liabilities measured on a recurring basis - (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	$ 143,078	$ 68,802	$ 268,321
Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Total assets measured at fair value	305,934	227,663
Level 1 | Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Total assets measured at fair value	212,121	199,708
Level 2 | Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Total assets measured at fair value	93,813	27,955
U.S. Treasury notes | Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Marketable securities	24,486	103,044
U.S. Treasury notes | Level 1 | Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Marketable securities	24,486	103,044
U. S. Government agency securities | Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Marketable securities	138,191	31,075
U. S. Government agency securities | Level 1 | Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Marketable securities	138,191	31,075
Corporate bonds | Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Marketable securities	88,983	23,970
Corporate bonds | Level 2 | Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Marketable securities	88,983	23,970
Commercial paper | Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Marketable securities	4,830	3,985
Commercial paper | Level 2 | Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Marketable securities	4,830	3,985
Money market funds
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	49,444	65,589
Money market funds | Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	49,444	65,589
Money market funds | Level 1 | Fair value, measurements, recurring
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	$ 49,444	$ 65,589

Cash, cash equivalents, restr_3

Cash, cash equivalents, restricted cash and available-for-sale marketable securities - Cash, cash equivalents, and marketable securities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023
Amortized Cost
Cash and cash equivalents	$ 143,078	$ 68,802	$ 268,321
Total money market funds and marketable securities	306,305	227,583
Debt securities, unrealized loss position	230,700	44,200
Marketable securities, non-current	980
Fair Value
Total money market funds and marketable securities	305,934	227,663
Unrealized Gains and Losses
Total money market funds and marketable securities	19	93
Total money market funds and marketable securities	(390)	(13)
Money market funds
Amortized Cost
Cash and cash equivalents	49,444	65,589
Fair Value
Cash and cash equivalents, fair value	49,444	65,589
U.S. Treasury notes
Amortized Cost
Marketable securities, amortized cost	24,540	102,966
Fair Value
Marketable securities, fair value	24,486	103,044
Unrealized Gains and Losses
Marketable securities, unrealized gains		81
Marketable securities, unrealized losses	(54)	(3)
U. S. Government agency securities
Amortized Cost
Marketable securities, amortized cost	138,285	31,068
Fair Value
Marketable securities, fair value	138,191	31,075
Unrealized Gains and Losses
Marketable securities, unrealized gains	7	10
Marketable securities, unrealized losses	(101)	(3)
Corporate bonds
Amortized Cost
Marketable securities, amortized cost	89,207	23,975
Fair Value
Marketable securities, fair value	88,983	23,970
Unrealized Gains and Losses
Marketable securities, unrealized gains	11	2
Marketable securities, unrealized losses	(235)	(7)
Commercial paper
Amortized Cost
Marketable securities, amortized cost	4,829	3,985
Fair Value
Marketable securities, fair value	4,830	$ 3,985
Unrealized Gains and Losses
Marketable securities, unrealized gains	$ 1

Cash, cash equivalents, restr_4

Cash, cash equivalents, restricted cash and available-for-sale marketable securities - Reconciliation of cash, cash equivalents, and restricted cash (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Cash, cash equivalents, restricted cash, and available-for-sale marketable securities
Cash and cash equivalents	$ 143,078	$ 68,802	$ 268,321
Restricted cash included in deposits and other noncurrent assets	$ 2,875		$ 1,515
Restricted Cash, Statement of Financial Position [Extensible Enumeration]	Deposits And Other Non-Current Assets		Deposits And Other Non-Current Assets
Total cash, cash equivalents, and restricted cash	$ 145,953	$ 70,395	$ 269,836	$ 100,474

Accrued expenses (Details)

Accrued expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Accrued expenses
Research and development costs	$ 2,914	$ 5,225
Employee compensation costs	2,248	6,614
Accrued goods and services	1,838	4,229
Professional services	595	755
Total	$ 7,595	$ 16,823

Lease obligation (Details)

Lease obligation (Details) $ in Thousands		3 Months Ended
	Aug. 11, 2023 USD ($) ft²	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Feb. 01, 2024 USD ($)	Dec. 31, 2023 USD ($)
Change in operating lease, right-of-use assets		$ (1,057)	$ (469)
Change in operating lease liabilities		891	(683)
Operating lease, right-of-use assets		39,204			$ 13,510
Lease liability		41,995			$ 17,093
Restricted cash included in deposits and other noncurrent assets		2,875	1,515
Lease expense		$ 1,700	$ 900
Weighted average remaining lease term		5 years 6 months
Weighted average incremental borrowing rate		6.90%
Total minimum lease payments
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]		Other Liabilities, Current			Other Liabilities, Current
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]		Other Liabilities, Noncurrent			Other Liabilities, Noncurrent
75 and 64 Sidney Street
Restricted cash included in deposits and other noncurrent assets		$ 2,900
75 Hayden avenue
Area of additional facility leased | ft²	61,307
Leasehold improvements amount	$ 1,800
Operating lease, right-of-use assets				$ 26,700
Lease liability				$ 26,700

Commitments, contingencies, and

Commitments, contingencies, and other liabilities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) multiple	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2017 USD ($)
Other current liabilities
Lease liability		$ 5,940	$ 3,200
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]		Total other current liabilities	Total other current liabilities
Total other current liabilities		$ 5,940	$ 3,200
Other non-current liabilities
Lease liability		$ 41,995	$ 17,093
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]		Total other non-current liabilities	Total other non-current liabilities
Other		$ 1,001	$ 1,001
Total other non-current liabilities		$ 42,996	$ 18,094
Non-profit organization agreement
Other non-current liabilities
Maximum funding	$ 4,000
Funding multiple | multiple	2.6
Milestone payment liability				$ 1,000

Significant Agreements - Neuroc

Significant Agreements - Neurocrine Collaboration Agreements (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024 USD ($) agreement	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of new agreements | agreement	0
Collaboration revenue	$ 19,516	$ 150,480	$ 150,500
2019 Neurocrine Collaborative Agreement | Neurocrine
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone payments received	5,000
Allocation of transaction price	5,000
Cumulative catch up of revenue recognized	4,400
2023 Neurocrine Collaborative Agreement | Neurocrine
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue recognized	$ 7,300

Significant Agreements - Novart

Significant Agreements - Novartis Agreements (Details) - Novartis Pharma, AG - 2023 Novartis Collaboration Agreement $ in Millions	Dec. 28, 2023 USD ($) shares
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Shares of common stock | shares	2,145,002
Aggregate purchase price	$ 20
Amount of premium	$ 0.7

Significant Agreements - Neur_2

Significant Agreements - Neurocrine Collaboration receivables and contract liabilities (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Related party collaboration receivables, beginning balance	$ 3,341
Related party collaboration receivables, ending balance	2,620
2023 Neurocrine Collaborative Agreement and 2019 Neurocrine Collaborative Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Related party collaboration receivables, beginning balance	3,341
Additions	7,340
Deductions	(8,061)
Related party collaboration receivables, ending balance	2,620
Deferred revenue, beginning balance	75,240
Additions	586
Deductions	(11,230)
Deferred revenue, ending balance	64,596
Discovery program 3 | Neurocrine | 2023 Neurocrine Collaborative Agreement and 2019 Neurocrine Collaborative Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Additions	600
Deductions	$ (11,200)

Stock-based compensation - Comp

Stock-based compensation - Compensation expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 3,573	$ 2,558
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	2,408	1,663
Restricted stock awards and units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	1,090	841
Employee stock purchase plan awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	75	54
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	1,280	863
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 2,293	$ 1,695

Stock-based compensation - Rest

Stock-based compensation - Restricted Stock - (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Restricted stock disclosures
Stock-based compensation.	$ 3,573	$ 2,558
Unvested restricted common stock units
Shares
Balance, beginning (in shares)	1,370,897
Granted (in shares)	696,908
Vested (in shares)	(324,520)
Forfeited (in shares)	(23,947)
Balance, ending (in shares)	1,719,338
Weighted Average Grant Date Fair Value Per Share
Balance, beginning (in dollars per share)	$ 6.65
Granted (in dollars per share)	7.63
Vested (in dollars per share)	5.75
Forfeited (in dollars per share)	6.42
Balance, ending (in dollars per share)	$ 7.22
Restricted stock disclosures
Vesting period	3 years
Stock-based compensation.	$ 1,090	841
Unrecognized stock-based compensation expense	$ 10,900
Remaining weighted-average remaining vesting period	2 years 4 months 24 days
Share-based Payment Arrangement, Employee | Unvested restricted common stock units
Restricted stock disclosures
Stock-based compensation.	$ 1,100	$ 800

Stock-based compensation - Stoc

Stock-based compensation - Stock Options - (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, beginning balance (in shares) | shares	7,425,444
Granted (in shares) | shares	1,747,626
Exercised (in shares) | shares	(32,500)
Cancelled or forfeited (in shares) | shares	(230,974)
Outstanding, ending balance (in shares) | shares	8,909,596
Exercisable (in shares) | shares	3,880,357
Weighted Average Exercise Price
Outstanding (in dollars per share) | $ / shares	$ 8.52
Granted (in dollars per share) | $ / shares	7.68
Exercised (in dollars per share) | $ / shares	4.91
Cancelled or forfeited (in dollars per share) | $ / shares	12.28
Outstanding (in dollars per share) | $ / shares	8.27
Exercisable (in dollars per share) | $ / shares	$ 9.04
Remaining Contractual Life
Outstanding	7 years 9 months 18 days
Exercisable	6 years 2 months 12 days
Aggregate Intrinsic Value
Outstanding | $	$ 17,875
Exercisable | $	8,728
Employee Stock Option [Member]
Options disclosures
Unrecognized stock-based compensation expense | $	$ 23,200
Remaining weighted-average remaining vesting period	3 years

Net (loss) income per share (De

Net (loss) income per share (Details) - shares	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities	10,651,434	8,741,904
Unvested restricted common stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities	22,500	45,000
Unvested restricted common stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities	1,719,338	1,336,159
Employee Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share
Antidilutive securities	8,909,596	7,360,745

Net (loss) income per share - B

Net (loss) income per share - Basic and diluted weighted average shares outstanding (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Numerator:
Net (loss) income	$ (11,330)	$ 124,044
Denominator for basic net income (loss) per share:
Weighted average shares outstanding-basic	57,117,046	40,632,087
Denominator for diluted net income (loss) per share:
Weighted average shares outstanding-basic	57,117,046	40,632,087
Common stock options and restricted stock units		1,529,239
Weighted average shares outstanding-diluted	57,117,046	42,161,326
Net (loss) income per share, basic	$ (0.20)	$ 3.05
Net (loss) income per share, diluted	$ (0.20)	$ 2.94

Underwritten public offering (D

Underwritten public offering (Details) - USD ($) $ / shares in Units, $ in Millions	Jan. 09, 2024	Jan. 04, 2024	Mar. 31, 2024	Dec. 31, 2023
Underwritten public offering
Par value of common stock (in dollars per share)			$ 0.001	$ 0.001
Underwriting Agreement
Underwritten public offering
Issuance of common stock, shares	7,777,778
Par value of common stock (in dollars per share)		$ 0.001
Offering price for common stock		$ 8.46
Period for option to exercise additional number of shares		30 days
Additional number of shares to be issued		1,666,665
Net proceeds received	$ 93.5
Underwriting Agreement | Pre-Funded Warrants
Underwritten public offering
Price per warrant		$ 8.459
Issuance of Pre-Funded Warrants	3,333,333
Underwriting Agreement | Pre-Funded Warrants | Maximum
Underwritten public offering
Number of warrants issued to purchase common stock	3,333,333

Related party transactions (Det

Related party transactions (Details)	3 Months Ended
	Mar. 31, 2024 USD ($) item	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)
Related party transactions
Related party collaboration receivable	$ 2,620,000		$ 3,341,000
Former Executives | Related Party | Board and scientific advisory services
Related party transactions
Number of individuals providing services | item	1
Dr. Sah | Related Party | Board and scientific advisory services
Related party transactions
Total amount of services received	$ 150,000	$ 199,800
Neurocrine Collaborative Agreement 2019
Related party transactions
Related party collaboration receivable	1,200,000
Neurocrine Collaborative Agreement 2023
Related party transactions
Related party collaboration receivable	$ 1,400,000

Subsequent Events - (Details)

Subsequent Events - (Details) - USD ($) $ in Millions	Jun. 30, 2024	Apr. 30, 2024
Neurocrine | Subsequent Event.
Subsequent Events
Milestone payment to be received	$ 3	$ 3

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (11,330)	$ 124,044

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Mar. 31, 2024 shares
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	Director and Officer Trading Arrangements ​ A portion of the compensation of our directors and officers (as defined in Rule 16a-1(f) under the Securities Exchange Act of 1934, as amended (the “Exchange Act”)) is in the form of equity awards and, from time to time, directors and officers engage in open-market transactions with respect to the securities acquired pursuant to such equity awards or our other securities, including to satisfy tax withholding obligations when equity awards vest or are exercised, and for diversification or other personal reasons. ​ Transactions in our securities by directors and officers are required to be made in accordance with our insider trading policy, which requires that the transactions be in accordance with applicable U.S. federal securities laws that prohibit trading while in possession of material nonpublic information. Rule 10b5-1 under the Exchange Act provides an affirmative defense that enables directors and officers to prearrange transactions in our securities in a manner that avoids concerns about initiating transactions while in possession of material nonpublic information. ​ The following table describes, for the quarterly period covered by this report, each trading arrangement for the sale or purchase of our securities adopted or terminated by our directors and officers that is either (1) a contract, instruction or written plan intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) (a “Rule 10b5-1 trading arrangement”) or (2) a “non-Rule 10b5-1 trading arrangement” (as defined in Item 408(c) of Regulation S-K): ​ ​ ​ ​ ​ ​ ​ Name (Title) Action Taken (Date of Action) Type of Trading Arrangement Nature of Trading Arrangement Duration of Trading Arrangement Aggregate Number of Securities Nancy Vitale ( Director ) Adoption ( March 19, 2024 ) Rule 10b5-1 trading arrangement for exercises of options and sales of shares Sale Until August 29, 2025, or such earlier date upon which all transactions are completed or expire without execution Up to 89,000 shares Toby Ferguson, M.D., Ph.D. ( Chief Medical Officer ) Adoption ( March 22, 2024 ) Durable Rule 10b5-1 trading arrangement for sell-to-cover transactions related to restricted stock units ("RSUs") granted on or after April 1, 2024 Sale Until final settlement of any covered RSU Indeterminable (1) ​ (1) The number of shares subject to covered RSUs that will be sold to satisfy applicable tax withholding obligations upon vesting is unknown as the number will vary based on the extent to which vesting conditions are satisfied, the market price of our common stock at the time of settlement, and the potential future grant of additional RSUs subject to this arrangement. This trading arrangement, which applies to RSUs whether vesting based on the passage of time or the achievement of performance goals, provides for the automatic sale of shares that would otherwise be issuable on each settlement date of a covered RSU in an amount sufficient to satisfy the applicable withholding obligation, with the proceeds of the sale delivered to us in satisfaction of the applicable withholding obligation.
Nancy Vitale
Trading Arrangements, by Individual
Name	Nancy Vitale
Title	Director
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	March 19, 2024
Aggregate Available	89,000
Toby Ferguson, M.D., Ph.D.
Trading Arrangements, by Individual
Name	Toby Ferguson, M.D., Ph.D.
Title	Chief Medical Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	March 22, 2024