Decibel Therapeutics (DBTX) 10-K 14 Mar 23 2022 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Mar. 01, 2023	Jun. 30, 2022
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Entity Registrant Name	DECIBEL THERAPEUTICS, INC.
Entity Central Index Key	0001656536
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		25,014,984
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity File Number	001-40030
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	46-4198709
Entity Address, Address Line One	1325 Boylston Street
Entity Address, Address Line Two	Suite 500
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02215
City Area Code	617
Local Phone Number	370-8701
Title of 12(b) Security	Common stock, par value $0.001 per share
Trading Symbol	DBTX
Security Exchange Name	NASDAQ
Document Annual Report	true
Document Transition Report	false
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
ICFR Auditor Attestation Flag	false
Entity Public Float			$ 70.8
Documents Incorporated by Reference	The registrant intends to file a definitive proxy statement pursuant to Regulation 14A relating to the 2023 Annual Meeting of Stockholders within 120 days of the end of the registrant’s fiscal year ended December 31, 2022 . Portions of such definitive proxy statement are incorporated by reference into Part III of this Annual Report on Form 10-K to the extent stated herein.
Auditor Name	Ernst & Young LLP
Auditor Firm ID	42
Auditor Location	Boston, Massachusetts

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 34,607	$ 36,455
Available-for-sale securities	69,954	112,292
Accounts receivable from related party		11,402
Prepaid expenses and other current assets	3,469	4,042
Total current assets	108,030	164,191
Available-for-sale securities, long-term		13,547
Property and equipment, net	4,526	5,611
Right-of-use asset, operating	9,859
Right-of-use asset, finance	34
Other assets	924	1,128
Total assets	123,373	184,477
Current liabilities:
Accounts payable	1,064	4,012
Accrued expenses and other current liabilities	8,409	7,712
Deferred collaboration liability, current	9,383	8,118
Deferred rent and lease incentive obligation, current		696
Operating lease liability, current	3,567
Finance lease liability, current	19
Total current liabilities	22,442	20,538
Long-term liabilities:
Deferred collaboration liability, long term	6,765	16,431
Deferred rent and lease incentive obligation, long term		4,208
Operating lease liability, long-term	10,467
Other long-term liabilities	1,906	1,611
Total liabilities	41,580	42,788
Commitments and contingencies (Note 8)
Stockholders' equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized, no shares issued and outstanding at December 31, 2022 and December 31, 2021
Common stock, $0.001 par value; 200,000,000 shares authorized, 24,964,502 shares issued and outstanding at December 31, 2022; 200,000,000 shares authorized, 24,964,520 shares issued and 24,951,983 shares outstanding at December 31, 2021	25	25
Additional paid-in capital	359,508	356,308
Accumulated other comprehensive loss	(223)	(132)
Accumulated deficit	(277,517)	(214,512)
Total stockholders' equity	81,793	141,689
Total liabilities and stockholders' equity	$ 123,373	$ 184,477

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2022	Dec. 31, 2021
Preferred stock, Par value	$ 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	$ 0.001	$ 0.001
Common stock, Shares authorized	200,000,000	200,000,000
Common stock, Shares issued	24,964,502	24,964,520
Common stock, Shares outstanding	24,964,502	24,951,983

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Operating expenses:
Research and development	$ 40,330	$ 29,847
General and administrative	23,627	20,384
Total operating expenses	63,957	50,231
Loss from operations	(63,957)	(50,231)
Other income:
Interest income	1,192	193
Other income, net		12
Total other income, net	1,192	205
Net loss before provision for income taxes	(62,765)	(50,026)
Provision for income taxes	(240)	(1,797)
Net loss	(63,005)	(51,823)
Cumulative dividends on convertible preferred stock		(2,309)
Net loss attributable to common stockholders	$ (63,005)	$ (54,132)
Net loss per share attributable to common stockholders, basic	$ (2.52)	$ (2.49)
Net loss per share attributable to common stockholders, diluted	$ (2.52)	$ (2.49)
Weighted-average shares of common stock outstanding, basic	24,960,008	21,733,960
Weighted-average shares of common stock outstanding, diluted	24,960,008	21,733,960
Comprehensive loss:
Net loss	$ (63,005)	$ (51,823)
Other comprehensive loss:
Unrealized loss on available-for-sale securities, net of tax of $0	(91)	(131)
Total other comprehensive loss	(91)	(131)
Comprehensive loss	$ (63,096)	$ (51,954)

CONSOLIDATED STATEMENTS OF OP_2

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Statement [Abstract]
Unrealized loss on available-for-sale securities, taxes	$ 0	$ 0

CONSOLIDATED STATEMENTS OF CONV

CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' (DEFICIT) EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit	Series A convertible preferred stock	Series B convertible preferred stock	Series C convertible preferred stock	Series D convertible preferred stock
Balance at Dec. 31, 2020	$ (54,781)	$ 1	$ 107,908	$ (1)	$ (162,689)
Balance, Shares at Dec. 31, 2020						57,758,734	12,500,000	37,528,581	31,740,554
Balance at Dec. 31, 2020						$ 16,176	$ 5,700	$ 16,759	$ 54,456
Balance, Shares at Dec. 31, 2020		521,052
Issuance of convertible preferred stock									$ 27,400
Issuance of convertible preferred stock, Shares									15,870,209
Issuance of common stock upon exercise of stock options	319		319
Issuance of common stock upon exercise of stock options, Shares		72,161
Vesting of restricted common stock	18		18
Vesting of restricted common stock, Shares		34,759
Stock-based compensation expense	2,817		2,817
Conversion of convertible preferred stock into common stock upon completion of initial public offering	120,491	$ 17	120,474
Conversion of convertible preferred stock into common stock upon completion of initial public offering, Shares						(57,758,734)	(12,500,000)	(37,528,581)	(47,610,763)
Conversion of convertible preferred stock into common stock upon completion of initial public offering						$ (16,176)	$ (5,700)	$ (16,759)	$ (81,856)
Conversion of convertible preferred stock into common stock upon completion of initial public offering, Shares		16,662,011
Issuance of common stock upon completion of initial public offering, net of commissions, underwriting discounts and offering costs	124,779	$ 7	124,772
Issuance of common stock upon completion of initial public offering, net of commissions, underwriting discounts and offering costs, Shares		7,662,000
Unrealized loss on available-for-sale securities	(131)			(131)
Net loss	(51,823)				(51,823)
Balance at Dec. 31, 2021	141,689	$ 25	356,308	(132)	(214,512)
Balance, Shares at Dec. 31, 2021		24,951,983
Vesting of restricted common stock, Shares		12,519
Stock-based compensation expense	$ 3,200		3,200
Conversion of convertible preferred stock into common stock upon completion of initial public offering, Shares	16,662,011
Unrealized loss on available-for-sale securities	$ (91)			(91)
Net loss	(63,005)				(63,005)
Balance at Dec. 31, 2022	$ 81,793	$ 25	$ 359,508	$ (223)	$ (277,517)
Balance, Shares at Dec. 31, 2022	0
Balance, Shares at Dec. 31, 2022		24,964,502

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' (DEFICIT) EQUITY (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($)
Statement of Stockholders' Equity [Abstract]
Payments of stock issuance costs	$ 13,137

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Operating activities
Net loss	$ (63,005)	$ (51,823)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	3,200	2,817
Depreciation	1,462	1,413
Non-cash lease expense	1,828
(Gain) loss on disposal of property and equipment		(35)
Amortization (accretion) of available-for-sale securities	235	987
Changes in operating assets and liabilities:
Accounts receivable from related party	11,402	(10,165)
Prepaid expenses and other current assets	611	(1,761)
Accounts payable	(3,128)	1,881
Accrued expenses and other current liabilities	941	3,438
Deferred rent and lease incentive		(607)
Deferred collaboration liability	(8,401)	9,404
Operating lease liability	(2,355)
Other long-term liabilities	312	1,301
Net cash used in operating activities	(56,898)	(43,150)
Investing activities
Purchases of available-for-sale securities	(97,513)	(197,457)
Proceeds from maturities of available-for-sale securities	153,073	97,068
Proceeds from sale of property and equipment		139
Purchases of property and equipment	(463)	(745)
Net cash provided by (used in) investing activities	55,097	(100,995)
Financing activities
Proceeds from the issuance of Series D convertible preferred stock		27,400
Proceeds from issuance of common stock upon completion of initial public offering net of commissions and underwriting discounts		128,240
Payment of initial public offering costs		(3,255)
Proceeds from the exercise of stock options		319
Principal payments on finance lease liability	(213)	(193)
Repurchases of early exercised restricted stock		(1)
Net cash (used in) provided by financing activities	(213)	152,510
Net (decrease) increase in cash, cash equivalents and restricted cash	(2,014)	8,365
Cash, cash equivalents and restricted cash at beginning of period	37,583	29,218
Cash, cash equivalents and restricted cash at end of period	35,569	37,583
Supplemental cash flow information:
Cash paid for interest for finance lease	14	34
Supplemental disclosure of non-cash activities:
Operating lease right-of-use asset recognized upon adoption of ASC 842	11,485
Property and equipment purchases in accounts payable and accrued expenses	$ 197	46
Vesting of early exercised restricted stock		$ 18

Nature of the Business

Nature of the Business	12 Months Ended
	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of the Business	1. Nature of the Business Decibel Therapeutics, Inc. (the “Company”) was formed on November 26, 2013. The Company is a clinical-stage biotechnology company dedicated to discovering and developing transformative treatments for hearing and balance disorders, one of the largest areas of unmet need in medicine. The Company aims to restore and improve hearing and balance through the restoration and regeneration of functional hair cells and non-sensory support cells within the inner ear. Initial Public Offering On February 17, 2021, the Company completed an initial public offering (“IPO”), issuing and selling 7,062,000 shares of common stock at a public offering price of $ 18.00 per share, and on February 24, 2021, the Company issued and sold an additional 600,000 shares pursuant to the underwriters’ partial exercise of their option to purchase additional shares. The aggregate net proceeds received by the Company from the offering were $ 125.0 million. Upon closing of the IPO, all outstanding shares of convertible preferred stock automatically converted into shares of common stock. In advance of the IPO, on February 5, 2021, the Company’s board of directors approved a 1-for-5.3 reverse stock split of the Company’s common stock. All share and per share amounts in the consolidated financial statements and notes thereto have been retroactively adjusted for all periods presented to give effect to the reverse stock split. Risks and Uncertainties The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry, including but not limited to, risks associated with completing preclinical studies and clinical trials, obtaining regulatory approvals for product candidates, development by competitors of new biopharmaceutical products, dependence on key personnel, protection of proprietary technology, compliance with government regulations and the ability to secure additional capital to fund operations. Programs currently under development will require significant additional research and development efforts, including preclinical and clinical testing and will need to obtain regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel and infrastructure and extensive compliance-reporting capabilities. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will realize revenue from product sales. The Company is also subject to additional risks and uncertainties related to the ongoing COVID-19 pandemic and other macroeconomic and geopolitical events, which collectively have caused and may continue to cause major disruptions to businesses and economies worldwide. The worldwide COVID-19 pandemic has affected and may affect in the future the Company’s ability to initiate and complete preclinical studies, delay the initiation and completion of the Company’s current and planned clinical trials, disrupt regulatory activities or have other adverse effects on the Company’s business, results of operations, financial condition and prospects. In addition, the pandemic has caused substantial disruption to global supply chains and may adversely impact economies worldwide, both of which could adversely affect the Company’s business, operations and ability to raise funds to support its operations. For example, due to increased quarantine mandates in China, the receipt of shipments and data from some of the Company's vendors and CROs were more difficult and unpredictable during the first half of 2022. This caused some delays in preclinical studies for the Company's gene therapy programs. The Company cannot be certain what the overall impact of the COVID-19 pandemic will be on its business. The extent of the impact of COVID-19 on its business will depend on the length and severity of the pandemic, including the extent there is any resurgence of the COVID-19 virus or any variant strains of the virus, the availability and effectiveness of vaccines and the impact of the foregoing on its preclinical studies, current and planned clinical trials, employees and vendors, which is uncertain and cannot be predicted. The pandemic has the potential to adversely affect its business, financial condition, results of operations and prospects. In addition, U.S. and global financial markets have experienced disruption due to various macroeconomic and geopolitical events. These include, but are not limited to, rising inflation, the risk of a recession and other ongoing global conflicts. The Company cannot predict at this time to what extent it and its collaborators, employees, suppliers, contract manufacturers and/or vendors could potentially be negatively impacted by these events. Liquidity The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry, including but not limited to, risks associated with completing preclinical studies and clinical trials, obtaining regulatory approvals for product candidates, development by competitors of new biopharmaceutical products, dependence on key personnel, protection of proprietary technology, compliance with government regulations and the ability to secure additional capital to fund operations. Programs currently under development will require significant additional research and development efforts, including preclinical and clinical testing and will need to obtain regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel and infrastructure and extensive compliance-reporting capabilities. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will realize revenue from product sales. In accordance with Accounting Standards Update (“ASU”) No. 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (Subtopic 205-40) (“ASU 2014-15”), management must evaluate whether there are conditions or events, when considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the financial statements are issued. This evaluation initially does not take into consideration the potential mitigating effect of management’s plans that have not been fully implemented as of the date the financial statements are issued. When substantial doubt exists under this methodology, management evaluates whether the mitigating effect of its plans sufficiently alleviates substantial doubt about the company’s ability to continue as a going concern. The mitigating effect of management’s plans, however, is only considered if both (1) it is probable that the plans will be effectively implemented within one year after the date that the financial statements are issued, and (2) it is probable that the plans, when implemented, will mitigate the relevant conditions or events that raise substantial doubt about the entity’s ability to continue as a going concern within one year after the date that the financial statements are issued. Generally, to be considered probable of being effectively implemented, the plans must have been approved before the date that the financial statements are issued. The Company's financial statements have been prepared on the basis of continuity of operations, realization of assets and the satisfaction of liabilities in the ordinary course of business. Since inception, the Company has incurred recurring losses and negative cash flows from operations in each period and on an aggregate basis. As of December 31, 2022, the Company had an accumulated deficit of $ 277.5 million . The Company expects its operating losses and negative operating cash flows to continue for the foreseeable future as it continues to invest significantly in the research and development of its product candidates, preclinical and clinical development and its platform. As of December 31, 2022, the Company had $ 104.6 million of cash, cash equivalents and available-for-sale securities which together with net proceeds raised under the Open Market Sale Agreement (“the Sales Agreement”) subsequent to December 31, 2022, may not be sufficient to fund its operations for at least twelve months from the date of issuance of these consolidated financial statements which raises substantial doubt about the Company’s ability to continue as a going concern. The future viability of the Company is dependent on its ability to raise additional capital to finance its operations. The Company has plans in place to mitigate this risk, which primarily consist of pursuing additional funding through the sale of equity, debt financings or other capital sources, including collaborations with other third parties, as well as by reducing cash expenditures. There is no guarantee that the Company will be successful in these mitigation efforts. The Company’s inability to raise capital as and when needed could have a negative impact on its financial condition and ability to pursue its business strategies. There can be no assurance that the current operating plan will be achieved or that additional funding will be available on terms acceptable to the Company, or at all. The accompanying consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the ordinary course of business. The consolidated financial statements do not include any adjustments relating to the recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might result from the outcome of this uncertainty.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation These consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASUs”) of the Financial Accounting Standards Board (“FASB”). Principles of Consolidation The accompanying consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries, Decibel Securities Corporation and Decibel Therapeutics Australia Pty. All intercompany balances and transactions have been eliminated in consolidation. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts in the financial statements and accompanying notes. Actual results could materially differ from those estimates. Management considers many factors in selecting appropriate financial accounting policies and controls, and in developing the estimates and assumptions that are used in the preparation of these consolidated financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes and management must select an amount that falls within that range of reasonable estimates. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, the estimated cost to perform research which is an input into the measurement of research and development expenses recognized under the Company’s collaboration agreement with Regeneron Pharmaceuticals, Inc. (“Regeneron”) , the accrual of research and development expenses, stock-based compensation expenses, leases and income taxes. Estimates are periodically reviewed considering changes in circumstances, facts and historical experience. Actual results may differ from the Company’s estimates. Segment Information Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision-maker in deciding how to allocate resources and assess performance. The Company and the Company’s chief operating decision-maker, the Company’s chief executive officer, view the Company’s operations and manages its business as a single operating segment. All of the Company’s long-lived assets are held in the United States. Cash, Cash Equivalents and Restricted Cash Cash equivalents are short-term, highly liquid investments that are readily convertible into cash, with original maturities of three months or less. Cash equivalents are mainly comprised of money market accounts invested in U.S. Treasury securities and agency bonds. Restricted cash is comprised of deposits with a financial institution used to collateralize letters of credit related to the Company’s lease arrangements. Restricted cash is presented as a component of prepaid expenses and other current assets and other assets on the consolidated balance sheets. Cash, cash equivalents and restricted cash consisted of the following (in thousands): December 31, 2022 2021 Cash and cash equivalents $ 34,607 $ 36,455 Restricted cash, current 38 — Restricted cash, long-term 924 1,128 Total cash, cash equivalents and restricted cash as shown on the statement $ 35,569 $ 37,583 Available-For-Sale Securities The Company classifies all of its investments as available-for-sale securities and reports them at fair value using quoted prices in active markets for similar securities. Unrealized gains and losses on available-for-sale securities are reported as accumulated other comprehensive loss, which is a separate component of stockholders’ equity. The cost of securities sold is determined on a specific identification basis, and realized gains and losses are included in other income (expense), net within the consolidated statements of operations and comprehensive loss. The Company regularly reviews all of its investments for other-than-temporary declines in estimated fair value. The Company’s review includes the consideration of the cause of the impairment, including the creditworthiness of the security issuers, the number of securities in an unrealized loss position, the severity and duration of the unrealized losses, whether the Company has the intent to sell the securities and whether it is more likely than not that the Company will be required to sell the securities before the recovery of their amortized cost basis. When the Company determines that the decline in estimated fair value of an investment is below the amortized cost basis and the decline is other-than-temporary, the Company reduces the carrying value of the security and records a loss for the amount of such decline. No such adjustments were necessary during the periods presented. The Company classifies its available-for-sale securities as current assets on the consolidated balance sheets if they mature within one year from the balance sheet date, and long-term available-for-sale securities if they mature longer than one year from the balance sheet date. Concentrations of Credit Risk and Significant Suppliers Financial instruments that potentially expose the Company to credit risk primarily consist of cash, cash equivalents, restricted cash and available-for-sale securities. The Company maintains its cash, cash equivalents, restricted cash and available-for-sale securities balances with accredited financial institutions and, consequently, the Company does not believe it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships. The Company’s cash management and investment policy limits investment instruments to U.S. Treasury and government securities with the objective to preserve capital and to maintain liquidity until the funds can be used in business operations. Bank accounts in the United States are insured by the Federal Deposit Insurance Corporation (“FDIC”) up to $ 250,000 . As of December 31, 2022 and 2021, the Company’s primary operating accounts significantly exceeded the FDIC limits. 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, other raw materials and formulated drugs related to these programs. These programs could be adversely affected by a significant interruption in the supply of active pharmaceutical ingredients, other raw materials and formulated drugs. Off-Balance Sheet Arrangements As of December 31, 2022, and 2021 , the Company had no off-balance sheet arrangements, as defined in the rules and regulations of the SEC. Fair Value Measurements Certain assets and liabilities of the Company are carried at fair value under GAAP. The fair values of the Company’s financial assets and liabilities reflect the Company’s estimate of the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: • Level 1—Quoted prices in active markets for identical assets or liabilities. • Level 2—Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. • Level 3—Unobservable inputs that are supported by little or no market activity that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. To the extent the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The carrying amounts reflected in the consolidated balance sheets for cash, accounts receivable, prepaid expenses and other current assets, accounts payable and accrued expenses approximate their fair values due to the short-term nature of these assets and liabilities. Items measured at fair value on a recurring basis include cash equivalents and available-for-sales securities as of December 31, 2022 and 2021 . Accounts Receivable, net The Company records accounts receivable for amounts invoiced to a collaborator, for which the Company has an unconditional right to consideration. For amounts to which the Company has an unconditional right to consideration but has not yet invoiced the collaborator, the Company records unbilled accounts receivable. The Company assesses the collectability for its accounts receivable and unbilled accounts receivable and records an allowance as deemed necessary. As of December 31, 2022 and 2021 , no allowance was recorded. Accounts receivable and unbilled accounts receivable are presented in accounts receivable, net on the consolidated balance sheets. Property and Equipment Property and equipment is stated at cost, net of accumulated depreciation and amortization. Depreciation and amortization are calculated using the straight-line method over the estimated useful lives of the assets, which are as follows: Estimated Useful Life Computer equipment and software 3 years Furniture and fixtures 7 years Laboratory equipment 5 years Leasehold improvements Shorter of useful life or remaining lease term Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation and amortization are removed from the accounts and any resulting gain or loss is included in income (loss) from operations. Expenditures for repairs and maintenance that do not improve or extend the lives of the respective assets are charged to expense as incurred, while costs of major additions and betterments are capitalized. Impairment of Long-Lived Assets The Company periodically evaluates its long-lived assets, which consist of property and equipment, for impairment whenever events or changes in circumstances indicate that a potential impairment may have occurred. If such events or changes in circumstances arise, the Company compares the carrying amount of the long-lived assets to the estimated future undiscounted cash flows expected to be generated by the long-lived assets. If the estimated aggregate undiscounted cash flows are less than the carrying amount of the long-lived assets, an impairment charge, calculated as the amount by which the carrying amount of the assets exceeds the estimated fair value of the assets, is recorded. The estimated fair value of the long-lived assets is determined based on the estimated discounted cash flows expected to be generated from the long-lived assets. Research and Development Costs and Accruals Research and development costs are expensed as incurred. Research and development expenses are comprised of costs incurred in performing research and development activities, including salaries, stock-based compensation and benefits, laboratory supplies, depreciation on and maintenance of research equipment, manufacturing expenses and external costs of outside vendors engaged to conduct preclinical and clinical development activities and the allocable portions of facility costs, such as rent, utilities, repairs and maintenance, depreciation, and general support services. Additionally, the consideration the Company receives under its license and collaboration agreement with Regeneron is being recognized as a reduction to research and development expense (contra-research and development expense) in the Company’s consolidated statements of operations and comprehensive loss based on the Company’s progress towards completion of its research activities under the research plan (see Note 13). Upfront payments and milestone payments made for the licensing of technology are expensed as research and development expenses in the period in which they are incurred. Nonrefundable advance payments for goods or services to be received in the future for use in research and development activities are recorded as prepaid expenses. The prepaid amounts are expensed as the related goods are delivered or the services are performed. The Company records accruals for estimated ongoing research and development costs. When evaluating the adequacy of the accrued liabilities, the Company analyzes progress of the preclinical studies or clinical trials, including the phase or completion of events, invoices received and contracted costs. Significant judgments and estimates are made in determining the accrued balances at the end of any reporting period. Actual results could differ from the Company’s estimates. The Company’s historical accrual estimates have not been materially different from the actual costs. Patent Costs All patent-related costs incurred in connection with filing, maintaining and prosecuting patent applications are expensed as incurred due to the uncertainty about the recovery of the expenditure. Amounts incurred are classified as general and administrative expenses. Stock-Based Compensation The Company issues stock-based awards to employees, directors and non-employee consultants, generally in the form of stock options, restricted stock and restricted stock units (“RSUs”). The Company accounts for its stock-based compensation awards in accordance with FASB ASC Topic 718, Compensation—Stock Compensation (“ASC 718”). ASC 718 requires stock-based payments to employees, qualifying directors and non-employees to be recognized as expense based on the fair value determined on the date of grant. The Company issues equity awards with service-based and performance-based vesting conditions. Compensation expense related to awards to employees, directors and non-employees with service-based vesting conditions is recognized on a straight-line basis based on the grant date fair value over the associated requisite service period of the award, which is generally the vesting term. Compensation expense related to awards to employees, directors and non-employees with performance-based vesting conditions is recognized when it becomes probable that the performance conditions will be met using the accelerated attribution method. The Company has no awards with market-based conditions. The Company recognizes forfeitures as they occur. The Company classifies stock-based compensation expense in the consolidated statements of operations and comprehensive loss in the same manner in which the award recipient’s salary and related costs are classified or in which the award recipient’s service payments are classified, as applicable. The Company determines the fair value of restricted stock and RSU awards in reference to the fair value of its common stock less any applicable purchase price. The Company estimates the fair value of its stock options using the Black-Scholes option pricing model, which requires inputs of subjective assumptions, including: (i) the expected volatility of its common stock, (ii) the expected term of the award, (iii) the risk-free interest rate, (iv) expected dividends and (v) the fair value of its common stock. Due to the lack of a public market for the trading of its common stock prior to the completion of its IPO and a lack of company-specific historical and implied volatility data, the Company bases the estimate of expected volatility on the historical volatilities of a representative group of publicly traded companies. For these analyses, the Company selects companies with comparable characteristics and with historical share price information that approximates the expected term of the stock-based awards. The Company computes the historical volatility data using the daily closing prices for the selected companies’ shares during the equivalent period that approximates the calculated expected term of its stock options. The Company will continue to apply this method until a sufficient amount of historical information regarding the volatility of its own stock price becomes available. The Company estimates the expected term of its stock options granted to employees and directors using the simplified method, whereby the expected term equals the average of the vesting term and the original contractual term of the option. The Company utilizes this method as it does not have sufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term. The expected dividend yield is assumed to be zero, as the Company has no current plans to pay any dividends on its common stock. The Company has elected to use the expected term for stock options granted to non-employees, using the simplified method, as the basis for the expected term assumption. However, the Company may elect to use either the contractual term or the expected term for stock options granted to non-employees on an award-by-award basis. Subsequent to the completion of the IPO, the fair value of the common stock underlying the Company’s stock-based awards is determined based on the trading price of its common stock on the Nasdaq Global Select Market on the date of grant. Leases The Company adopted FASB ASU No. 2016-02, Leases (“ASC 842”), effective January 1, 2022 using the required modified retrospective approach and utilizing the effective date as its date of initial application. Prior periods are presented in accordance with previous guidance in FASB ASC Topic 840, Leases. The Company evaluates whether an arrangement is or contains a lease at contract inception. If a contract is or contains a lease, lease classification is determined at lease commencement, which represents the date at which the underlying asset is made available for use by the Company. The Company’s lease terms are generally measured as the respective lease’s noncancelable term and exclude any optional extension terms as the Company is not reasonably certain to exercise such options. The Company elected the short-term lease exemption and therefore does not recognize lease liabilities and right-of-use assets for lease arrangements with original lease terms of twelve months or less. Lease liabilities represent the Company’s obligation to make lease payments under a lease arrangement. Lease liabilities are measured as the present value of fixed lease payments, discounted using an incremental borrowing rate, as interest rates implicit in the Company’s lease arrangements are generally not readily determinable. The Company elected the practical expedient to not separate lease and non-lease components for its real estate leases and therefore both are considered when determining the lease payments in a lease arrangement. Variable lease costs are expensed as incurred. The incremental borrowing rate represents the interest rate at which the Company could borrow a fully collateralized amount equal to the lease payments, over a similar term, in a similar economic environment. The Company determines the incremental borrowing rate at lease commencement, generally using a synthetic credit rating based on the Company’s financial position and negative cash flows, factoring in adjustments for additional risks based on the Company’s economic condition, a survey of comparable companies with similar credit and financial profiles, as well as additional market risks, as may be applicable. Right-of-use assets represent the Company’s right to use an underlying asset over its lease term. Right-of-use assets are initially measured as the associated lease liability, adjusted for prepaid rent and tenant incentives. The Company remeasures right-of-use assets and lease liabilities when a lease is modified, and the modification is not accounted for as a separate contract. A modification is accounted for as a separate contract if the modification grants the Company an additional right of use not included in the original lease agreement and the increase in lease payments is commensurate with the additional right of use. The Company assesses its right-of-use assets for impairment consistent with its policy for impairment of long-lived assets held and used in operations. Income Taxes Income taxes are recorded in accordance with FASB ASC Topic 740, Income Taxes (“ASC 740”), which provides for deferred taxes using an asset and liability approach. The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the consolidated financial statements or tax returns. Deferred tax assets and liabilities are determined based on the difference between the consolidated financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The Company assesses the likelihood that its deferred tax assets will be recovered from future taxable income and, to the extent it believes, based upon the weight of available evidence, that it is more likely than not that all or a portion of the deferred tax assets will not be realized, a valuation allowance is established through a charge to income tax expense. Potential for recovery of deferred tax assets is evaluated by estimating the future taxable profits expected and considering prudent and feasible tax planning strategies. Should the actual amounts differ from these estimates, the amount of the Company’s valuation allowance could be materially impacted. Changes in these estimates may result in significant increases or decreases to the tax provision in a period in which such estimates are changed, which in turn would affect net income or loss. The Company accounts for uncertainty in income taxes recognized in the consolidated financial statements by applying a two-step process to determine the amount of tax benefit to be recognized. First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination by the taxing authorities. If the tax position is deemed more-likely-than-not to be sustained, the tax position is then assessed to determine the amount of benefit to recognize in the consolidated financial statements. The amount of the benefit that may be recognized is the largest amount that has a greater than 50% likelihood of being realized upon ultimate settlement. Derecognition of a tax position that was previously recognized occurs when the Company subsequently determines that a tax position no longer meets the more likely than not threshold. To the extent an income tax provision is necessary, the provision for income taxes would include the effects of any resulting tax reserves, or unrecognized tax benefits, that are considered appropriate as well as the related net interest and penalties. The provision for income taxes includes the effects of any resulting tax reserves or unrecognized tax benefits that are considered appropriate as well as the related net interest and penalties. Comprehensive Loss Comprehensive loss includes net loss as well as other changes in stockholders’ equity that result from transactions and economic events other than those with stockholders. Other comprehensive loss for all periods presented consists solely of unrealized gains (losses) on available-for-sale securities. Revenue Recognition The Company recognizes revenue from contracts with customers under FASB ASC Topic 606, Revenue from Contracts with Customers (“ASC 606”). The Company has not had any transactions that fall within the scope of ASC 606, but does use ASC 606 by analogy for the measurement and recognition of contra-research and development expense under its collaboration agreement, which is accounted for under FASB ASC Topic 808, Collaborative Agreements (“Topic 808”). Under ASC 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the entity expects to receive in exchange for those goods or services. To determine the appropriate amount of revenue to be recognized for arrangements determined to be within the scope of ASC 606, the Company will perform the following five steps: (i) identification of the contract(s) with the customer, (ii) identification of the promised goods or services in the contract and determination of whether the promised goods or services are performance obligations, (iii) measurement of the transaction price, (iv) allocation of the transaction price to the performance obligations and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. The Company will account for a contract with a customer that is within the scope of ASC 606 when all of the following criteria are met: (i) the arrangement has been approved by the parties and the parties are committed to perform their respective obligations, (ii) each party’s rights regarding the goods or services to be transferred can be identified, (iii) the payment terms for the goods or services to be transferred can be identified, (iv) the arrangement has commercial substance and (v) collection of substantially all of the consideration to which the Company will be entitled in exchange for the goods or services that will be transferred to the customer is probable. The Company estimates the transaction price based on the amount of consideration the Company expects to be received for transferring the promised goods or services in the contract. The consideration may include both fixed consideration and variable consideration. For each arrangement that includes variable consideration, the Company evaluates the amount of the potential payments and the likelihood that the payments will be received. The Company utilizes either the most likely amount method or expected value method to estimate the transaction price based on which method better predicts the amount of consideration expected to be received. If it is probable that a significant revenue reversal would not occur, the variable consideration is included in the transaction price. For arrangements that include development and regulatory milestone payments, the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company’s control or the licensee’s control, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. At the end of each reporting period, the Company re-evaluates the probability of achievement of such milestones and any related constraint, and if necessary, adjusts the estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect collaboration revenue and net loss in the period of adjustment. For sales-based royalties, including milestone payments based on the level of sales, the Company determines whether the sole or predominant item to which the royalties relate is a license. When the license is the sole or predominant item to which the sales-based royalty relates, the Company recognizes revenue at the later of: (i) when the related sales occur or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). The Company allocates the transaction price to each performance obligation based on the relative estimated standalone selling price of the performance obligations. The Company must develop assumptions that require judgment to determine the standalone selling price for each performance obligation identified in the contract. The Company utilizes key assumptions to determine the standalone selling price, which may include other comparable transactions, pricing considered in negotiating the transaction and the estimated costs. Certain variable consideration is allocated specifically to one or more performance obligations in a contract when the terms of the variable consideration relate to the satisfaction of the performance obligation and the resulting amounts allocated to each performance obligation are consistent with the amounts the Company would expect to receive for each performance obligation. For performance obligations which consist of licenses and other promises, the Company utilizes judgment to assess the nature of the combined performance obligation in order to determine whether the combined performance obligation is satisfied over time or at a point in time. The Company determines the appropriate method of measuring progress of combined performance obligations satisfied over time for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. If the license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company will recognize revenue from non-refundable, upfront fees allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. Collaboration Agreements The Company analyzes its collaboration arrangements to assess whether they are within the scope of Topic 808 to determine whether such arrangements involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards that are dependent on the commercial success of such activities. To the extent the arrangement is within the scope of Topic 808, the Company assesses whether aspects of the arrangement between the Company and its collaboration partner are within the scope of other accounting literature, including ASC 606. If it is concluded that some or all aspects of the arrangement represent a transaction with a customer, the Company will account for those aspects of the arrangement within the scope of ASC 606. Pursuant to ASC 606, a customer is a party that has contracted with an entity to obtain goods or services that are an output of the entity’s ordinary activities in exchange for consideration. Under ASC 606, an entity recognizes revenue when its customer obtains control of promised goods or services in an amount that reflects the consideration which the entity expects to receive in exchange for those goods or services. ASC 808 provides guidance for the presentation and disclosure of transactions in collaborative arrangements, but it does not provide recognition or measurement guidance. Therefore, if the Company concludes a counterparty to a transaction is not a customer or otherwise not within the scope of ASC 606, the Company considers the guidance in other accounting literature, including the guidance in ASC 606, as applicable or by analogy to account for such transaction. The classification of transactions under the Company’s arrangements is determined based on the nature and contractual terms of the arrangement along with the

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair Value Measurements The Company measures the following financial assets at fair value on a recurring basis. The fair value of these assets was determined as follows (in thousands): Balance at December 31, 2022 Quoted Prices Significant Significant Cash equivalents: Money market mutual funds $ 34,059 $ 34,059 $ — $ — Total cash equivalents $ 34,059 $ 34,059 $ — $ — Available-for-sale securities: U.S. Treasury securities $ 36,246 $ — $ 36,246 $ — U.S. Agency bonds 22,523 — 22,523 — U.S. Agency discount notes 11,185 — 11,185 — Total available-for-sale securities $ 69,954 $ — $ 69,954 $ — Balance at Quoted Prices Significant Significant Cash equivalents: Money market mutual funds $ 31,726 $ 31,726 $ — $ — Total cash equivalents $ 31,726 $ 31,726 $ — $ — Available-for-sale securities: U.S. Treasury securities $ 61,373 $ — $ 61,373 $ — Corporate debt securities 33,806 — 33,806 — U.S. Agency bonds 15,114 — 15,114 — Commercial paper 1,999 — 1,999 — Total available-for-sale securities $ 112,292 $ — $ 112,292 $ — Available-for-sale securities, long-term: U.S. Treasury securities $ 13,547 $ — $ 13,547 $ — Total available-for-sale securities, long-term $ 13,547 $ — $ 13,547 $ — Money market funds were valued by the Company using quoted prices in active markets for identical securities, which represent a Level 1 measurement within the fair value hierarchy. The Company’s available-for-sale securities were valued based on Level 2 inputs and in determining the fair value the Company relied on quoted prices for similar securities in active markets or other inputs that are observable or can be corroborated by observable market data. During the years ended December 31, 2 0 22 and 2 0 21 , there were no changes in valuation techniques or transfers between Level 1, Level 2 and Level 3. There were no liabilities measured at fair value on a recurring basis as of December 31, 2022 or 2021.

Available-for-sale Securities

Available-for-sale Securities	12 Months Ended
	Dec. 31, 2022
Investments, Debt and Equity Securities [Abstract]
Available-for-sale Securities	4. Available-For-Sale Securities The following table summarizes the Company’s available-for-sale securities (in thousands): December 31, 2022 Amortized Gross Gross Fair Value Available-for-sale securities: U.S. Treasury securities $ 36,452 $ — $ ( 206 ) $ 36,246 U.S. Agency bonds 22,550 8 ( 35 ) 22,523 U.S. Agency discount notes 11,175 10 — 11,185 Total available-for-sale securities $ 70,177 $ 18 $ ( 241 ) $ 69,954 December 31, 2021 Amortized Gross Gross Fair Value Available-for-sale securities: U.S. Treasury securities $ 61,450 $ — $ ( 77 ) $ 61,373 Corporate debt securities 33,814 — ( 8 ) 33,806 U.S. Agency bonds 15,123 — ( 9 ) 15,114 Commercial paper 1,999 — — 1,999 Total available-for-sale securities $ 112,386 $ — $ ( 94 ) $ 112,292 Available-for-sale securities, long-term: U.S. Treasury securities $ 13,585 $ — $ ( 38 ) $ 13,547 Total available-for-sale securities, long-term $ 13,585 $ — $ ( 38 ) $ 13,547 The Company had 25 investments in available-for-sale securities in an unrealized loss position as of December 31, 2022 with a fair value of $ 48.1 million. The Company had 43 investments in available-for-sale securities in an unrealized loss position as of December 31, 2021 with a fair value of $ 120.3 million. These investments were in a loss position for less than 12 months and the Company considered the loss to be temporary in nature. The Company considered the decline in market value for these securities to be primarily attributable to economic and market conditions. As of December 31, 2022 and 2021, the Company did not intend to sell, and it was not more likely than not that the Company would be required to sell the investments that were in an unrealized loss position before recovery of their amortized cost basis. Accordingly, the Company did no t recognize any other-than-temporary impairments related to its available-for-sale securities in an unrealized loss position. As of December 31, 2022, the Company did not hold any investments that matured beyond one year , and as of December 31, 2021 , the Company did not hold any investments that matured beyond five years . During the years ended December 31, 2022 and 2021, the Company did not sell any available-for-sale securities and therefore did no t recognize any realized gains or losses.

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Property and Equipment, Net	5. Property and Equipment, Net Property and equipment, net consisted of the following (in thousands): December 31, 2022 2021 Leasehold improvements $ 7,096 $ 7,096 Laboratory equipment 3,406 3,339 Computer equipment and software 212 212 Furniture and fixtures 947 947 Construction in progress 40 — Total property and equipment 11,701 11,594 Accumulated depreciation ( 7,175 ) ( 5,983 ) Property and equipment, net $ 4,526 $ 5,611 The Company incurred depreciation expense of $ 1.5 million and $ 1.4 million for the years ended December 31, 2022 and 2021 , respectively.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	12 Months Ended
	Dec. 31, 2022
Payables and Accruals [Abstract]
Accrued Expenses and Other Current Liabilities	6. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consisted of the following (in thousands): Years Ended December 31, 2022 2021 Accrued research and development expenses $ 3,469 $ 3,152 Accrued compensation and related expenses 2,883 2,932 Accrued professional fees 1,170 380 Other accrued expenses 887 1,035 Equipment financing, current — 213 $ 8,409 $ 7,712

Leases

Leases	12 Months Ended
	Dec. 31, 2022
Leases [Abstract]
Leases	7. Leases Operating Leases In July 2016, the Company entered into an operating lease for its facility in Boston, Massachusetts. Under the terms of the lease agreement, rent payments commenced in June 2017 with base rent in the first lease year of $ 2.1 million, subject to annual increases of 3.0 % over the lease term through June 2027 . The Company is also obligated to pay its ratable portion of operating expenses and taxes. The Company has the right to extend the lease for one additional five-year period at a market rental rate as determined by the landlord and agreed to by the Company. The lease is secured by a letter of credit in the amount of $ 0.5 million. In conjunction with the lease, the landlord provided the Company with a $ 5.3 million tenant improvement allowance. In September 2019, the Company entered into an operating lease under which the Company leased additional office space from a separate third-party tenant under a sublease agreement at its existing facility. Under the terms of the lease agreement, rent payments commenced in December 2019 with base rent in the first lease year of $ 1.2 million, subject to annual rent escalation over the lease term through January 2027 . The sublease is secured by a letter of credit in the amount of $ 0.3 million. In January 2020, the Company entered into a sublease agreement to sublease a portion of its existing office and laboratory space to a third-party. The lease term commenced in March 2020 with an original term of 24 months . Annual base rent was $ 1.1 million for each year during the sublease term. The sublessee was obligated to pay its ratable portion of operating expenses during the sublease term. Subject to the Company’s consent, the sublease provided the sublessee one option to extend for up to one year , subject to a 3.0 % rent increase. In May 2021, the sublessee exercised its right to extend the sublease term through October 31, 2022 . Pursuant to the extension, base rent was $ 1.7 million for each year during the extension term. The sublessee provided a security deposit of $ 0.2 million in cash which was presented as a component of accrued expenses and other current liabilities on the consolidated balance sheet. Payments received under the sublease were recorded as a reduction to rent expense in the consolidated statements of operations and comprehensive loss. In January 2022, the Company entered into a sublease agreement to sublease an additional portion of its existing office space to a third-party. The lease term commenced in February 2022 with an original term of six months . Base rent over the term amounted to $ 0.5 million. The sublease granted the sublessee the right to extend for two terms of three months each at the same base rent per month for an additional $ 0.3 million for each term. In June 2022, the sublessee exercised its first right to extend the sublease term and in September 2022, the sublessee exercised its second right to extend the sublease term. In January 2023, the Company and sublessee amended the sublease agreement to extend the sublease term through May 2023 at the same base rent per month. There is no rent escalation under the amended sublease and there is no option to further extend the term of the sublease agreement. The sublessee prepaid the last month’s rent of $ 0.1 million, which is presented as a component of accrued expenses and other current liabilities on the consolidated balance sheet. Payments received under the sublease are recorded as a reduction to rent expense in the consolidated statements of operations and comprehensive loss. Finance Leases In July 2020, the Company entered into a financing transaction with a third-party leasing company. Pursuant to the transaction, the Company transferred title and interest in certain laboratory equipment to the third party in exchange for a one-time cash payment of $ 0.5 million and agreed to lease the laboratory equipment back from the third party for $ 0.2 million per year for 2.5 years. The Company concluded the lease was a capital lease under ASC 840 and a finance lease after the Company’s adoption of ASC 842. The components of lease cost for the year ended December 31, 2022 were as follows (in thousands): Operating lease cost $ 2,917 Variable lease cost 782 Short-term lease cost 17 Finance lease cost: Amortization of right-of-use assets 201 Interest expense on lease liabilities 14 Sublease income ( 2,476 ) Total lease cost $ 1,455 Supplemental cash flow information related to the Company's leases for the year ended December 31, 2022 were as follow (in thousands): Cash paid for amounts included in the measurement of lease liabilities Operating cash flows for operating leases $ 3,616 Operating cash flows for finance leases $ 14 Financing cash flows for finance leases $ 213 Future minimum lease payments under the Company’s noncancelable leases as of December 31, 2022 were as follows (in thousands): Operating Leases Finance Leases 2023 $ 3,705 $ 19 2024 3,796 — 2025 3,889 — 2026 3,984 — 2027 1,350 — Total lease payments 16,724 19 Present value adjustment ( 2,690 ) — Present value of lease payments $ 14,034 $ 19 As of December 31, 2022 , the Company’s operating leases had a weighted-average remaining lease term of 4.3 years and weighted average incremental borrowing rate of 8.7 %. As of December 31, 2022 , the Company’s finance lease had a weighted average remaining lease term of 0.1 years and weighted average incremental borrowing rate of 10.0 %.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	8 . Commitments and Contingencies License Agreement with University of Florida Research Foundation In October 2020, the Company entered into a license agreement with University of Florida Research Foundation, Incorporated (“UFRF”), which was amended in June 2022, relating to certain patent rights related to compositions and methods for expressing otoferlin (the “UFRF License”). Under the UFRF License, the Company acquired an exclusive, sublicensable, worldwide license to make, have made, use, sell, have sold, and import products covered by the licensed patent rights. Under the UFRF License, UFRF retains the right for itself and any non-profit institution or governmental entity to practice and have practiced certain of the licensed intellectual property rights for research, clinical, and educational purposes. The UFRF License is also subject to pre-existing rights of the U.S. government. The Company paid UFRF an upfront fee of $ 0.1 million and agreed to pay UFRF an additional $ 0.1 million following the issuance of the first patent under the UFRF License. In addition, under the terms of the UFRF License, the Company is required to pay to UFRF certain nominal annual license maintenance fees until the first year in which it sells a licensed product. Under the UFRF License, the Company has agreed to pay UFRF a low single-digit royalty on annual net sales of licensed products. The obligation to pay royalties continues on a licensed-product-by-licensed-product and country-by-country basis until the expiration of the last of the patent rights licensed under the UFRF License. In addition, the Company is obligated to make contingent milestone payments to UFRF totaling up to $ 0.8 million in the aggregate upon the achievement of certain clinical and regulatory milestones and up to an additional $ 11.2 million in the aggregate upon the achievement of certain commercial sales milestones, in each case, whether achieved by the Company or its sublicensee. No clinical, regulatory or commercial milestones have been achieved to date. In the event that the Company sublicenses the licensed patent rights, UFRF is also entitled to receive a percentage of the sublicensing revenue received by the Company. Under the UFRF License, the Company is obligated to use commercially reasonable efforts to develop, commercialize and maintain supply of licensed product. The Company also agreed to meet specified development, regulatory and commercialization milestones for the licensed patent rights by specified dates, subject to extensions that may be granted by UFRF under certain circumstances. UFRF has the right to terminate the license if the Company fails to perform its diligence obligations. The agreement will continue on a licensed-product-by-licensed-product and country-by-country basis until the last to expire of the patent rights under the UFRF License. The Company may terminate the agreement by providing prior written notice to UFRF. UFRF has the right to terminate the agreement if the Company fails to make any payments, bring action or proceeding against UFRF or otherwise breach the agreement and fail to cure such breach within a specified grace period. In addition, the agreement will immediately terminate upon certain events of insolvency of either party. All payments made to UFRF have been expensed as research and development expenses in the consolidated statements of operations and comprehensive loss. The consolidated financial statements as of December 31, 2022 and 2021 do not include liabilities with respect to this license agreement as the Company has not yet generated revenue and the achievement of certain milestones is not probable. License Agreement with The Regents of The University of California In October 2019, the Company entered into a license agreement with The Regents of the University of California (“UCSF”) relating to certain patent rights related to compositions and methods for expressing otoferlin, which is referred to collectively as the UCSF License. Under the UCSF License, the Company acquired an exclusive, sublicensable, worldwide license to make, have made, use, sell, offer for sale and import products, services, and methods covered by the licensed patent rights, and to perform licensed processes. Under the UCSF License, UCSF retains the right to make, use and practice certain of the licensed intellectual property rights for research and educational purposes, and the right to license to other academic and nonprofit organizations to practice the patent rights for research and educational purposes. The UCSF License is also subject to pre-existing rights of the U.S. government and the National Institutes of Health. The Company paid to UCSF a nominal upfront fee and agreed to pay UCSF an additional nominal fee following the issuance of the first patent under the UCSF License. In addition, under the terms of the UCSF License, the Company is required to pay to UCSF certain nominal annual license maintenance fees unless the Company is selling or otherwise exploiting licensed products or services paying royalties to UCSF on net sales for such licensed products or services. With respect to such royalty obligations, the Company agreed to pay UCSF low single-digit royalties on annual net sales of licensed products and services. The Company’s obligation to pay royalties continues until the expiration or abandonment of the last of the patent rights licensed under the UCSF License. In addition, the Company is obligated to make contingent milestone payments to UCSF totaling up to $ 0.5 million upon the achievement of certain regulatory milestones and up to $ 5.0 million upon the achievement of certain commercial sales milestones whether achieved by the Company or its sublicensee. No regulatory or commercial milestones have been achieved to date. In the event that the Company sublicenses the licensed patent rights, UCSF is also entitled to receive a percentage of the sublicensing income received by the Company. Under the UCSF License, the Company is obligated to diligently proceed with the development, manufacture and sale of at least one licensed product and/or service, and to earnestly and diligently market such licensed product and/or service after receipt of any requisite regulatory approvals and in quantities sufficient to meet market demand. The Company has also agreed to meet specified development, regulatory and commercialization milestones for the licensed patent rights by specified dates, subject to extensions that may be granted by UCSF under certain circumstances. UCSF has the right to revoke the Company’s right to sublicense the UCSF License or reduce the license to a nonexclusive license if the Company is unable to perform its diligence obligations. The agreement will continue until the last to expire or abandonment of the patent rights under the UCSF License. The Company may terminate the agreement by providing prior written notice to UCSF or it may terminate the rights under patent rights on a country-by-country basis by giving notice in writing to UCSF. UCSF has the right to terminate the agreement if the Company fails to make any payments, challenge any UCSF patent rights or otherwise materially breach the agreement and fail to cure such breach within a specified grace period. All payments made to UCSF have been expensed as research and development expenses in the consolidated statements of operations and comprehensive loss. The consolidated financial statements as of December 31, 2022 and 2021 do not include liabilities with respect to this license agreement as the Company has not yet generated revenue and the achievement of certain milestones is not probable. License Agreement with The Curators of the University of Missouri In August 2019, the Company entered into a license agreement with The Curators of the University of Missouri (the “University of Missouri”), which was amended in February 2021 and May 2022, relating to certain patent rights related to the AAV vectors it is using in the gene therapies the Company is developing for congenital, monogenic hearing loss due to an otoferlin deficiency and due to a deficiency in another specified gene, which is referred to collectively as the University of Missouri License. Under the University of Missouri License, the Company acquired an exclusive license to make, have made, use, sell, have sold, import, distribute or otherwise transfer products (the “licensed products”), covered by the licensed patent rights. The Company may sublicense the licensed patent rights with the University of Missouri’s prior written approval. Under the University of Missouri License, the University of Missouri retains the right to make, use and practice certain of the licensed intellectual property rights for non-commercial research purposes and the right to license to nonprofit, academic or government institutions the patent rights for non-commercial research purposes. The University of Missouri License is also subject to pre-existing rights of the U.S. government and the National Institutes of Health. The Company paid to the University of Missouri a $ 0.1 million upfront fee and agreed to pay the University of Missouri a nominal annual license maintenance fee. In addition, the Company agreed to pay to the University of Missouri a low single-digit royalty on annual net sales of licensed products sold regardless of where such licensed products are manufactured and an additional low single-digit royalty on annual net sales of licensed products that are sold outside of the United States but manufactured within the United States, with a specified minimum annual royalty requirement. The Company’s obligation to pay royalties continues until the expiration or abandonment of the last of the patent rights licensed under the University of Missouri License. In addition, the Company is obligated to make milestone payments on a licensed-product-by-licensed-product basis to the University of Missouri totaling up to $ 0.8 million in the aggregate upon the achievement of certain development and regulatory milestones and up to $ 13.1 million in the aggregate upon the achievement of certain commercial sales milestones, whether achieved by the Company or its sublicensee. During the year ended December 31, 2022 the Company achieved and paid less than $ 0.1 million with respect to a regulatory milestone related to the Company’s submission of an investigational new drug application (“IND”), for the Company's lead developmental gene therapy, DB-OTO. In the event that the Company sublicenses the licensed patent rights, the University of Missouri is also entitled to receive a tiered percentage of the sublicensing revenue received by the Company, which varies depending on the stage of development at which the Company enters into such sublicense. Under the University of Missouri License, the Company is obligated to use reasonable commercial efforts to advance the licensed product towards commercialization. The Company has also agreed to meet specified development, regulatory and commercialization milestones for the licensed patent rights by specified dates. The University of Missouri has the right to unilaterally terminate the University of Missouri License or reduce the license to a nonexclusive license if the Company fails to meet such specified milestones. The agreement will continue until the last to expire or abandonment of the patent rights under the University of Missouri License. The Company may terminate the agreement by providing prior written notice to the University of Missouri or upon the uncured material breach of the agreement by the University of Missouri. The University of Missouri has the right to terminate the agreement if the Company fails to make any payments, upon the occurrence of certain events of insolvency for the Company, challenge any University of Missouri patent rights or otherwise materially breach the agreement and fail to cure such breach within a specified grace period. All payments made to the University of Missouri have been expensed as research and development expenses in the consolidated statements of operations and comprehensive loss. The consolidated financial statements as of December 31, 2022 and 2021 do not include liabilities with respect to this license agreement as the Company has not yet generated revenue and the achievement of certain milestones is not probable. Purchase Orders The Company has agreements with third parties for various services, including services related to preclinical operations and support, for which the Company is not contractually able to terminate for convenience to avoid future obligations to the vendors. Certain agreements provide for termination rights subject to termination fees or wind down costs. Under such agreements, the Company is contractually obligated to make certain payments to vendors, primarily to reimburse them for their unrecoverable outlays incurred prior to cancelation. The actual amounts the Company could pay in the future to the vendors under such agreements may differ from the purchase order amounts due to cancellation provisions. Indemnification Agreements The Company enters into standard indemnification agreements and/or indemnification sections in other agreements in the ordinary course of business. Pursuant to the agreements, the Company indemnifies, holds harmless, and agrees to reimburse the indemnified party for losses suffered or incurred by the indemnified party, generally the Company’s business partners. The term of these indemnification agreements is generally perpetual any time after execution of the agreement. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements and/or sections is unlimited. The Company has never incurred costs to defend lawsuits or settle claims related to these indemnification agreements and/or sections. The Company does not believe that the outcome of any claims under indemnification arrangements will have a material effect on its financial position, results of operations or cash flows, and it had not accrued any liabilities related to such obligations in its consolidated financial statements as of December 31, 2022 or 2021. Legal Proceedings From time to time, the Company may become party to litigation or other legal proceedings as part of its ordinary course of business. As of December 31, 2022, the Company is not currently party to any material legal proceedings. At each reporting date, the Company evaluates whether or not a potential loss amount or a potential range of loss is probable and reasonably estimable under the provisions of FASB ASC Topic 450, Contingencies . The Company expenses as incurred the costs related to its legal proceedings.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2022
Equity [Abstract]
Stockholders' Equity	9. Stockholders' Equity As of December 31, 2022 and 2021, the Company’s Certificate of Incorporation authorized the Company to issue 200,000,000 shares of common stock, $ 0.001 par value, and 5,000,000 shares of undesignated preferred stock, $ 0.001 par value per share. The rights, preferences and privileges of the Company’s common stock are as follows: Voting The holders of shares of common stock are entitled to one vote for each share of common stock held on all matters submitted to a vote of the Company’s stockholders. Dividends The holders of shares of common stock are not entitled to receive dividends, unless declared by the Company’s board of directors, subject to any preferential dividend or other rights of any then-outstanding preferred stock. No dividends have been declared or paid by the Company since its inception. Liquidation After the payment of all preferential amounts required to be paid to the holders of shares of the Company’s then-outstanding preferred stock, the remaining assets of the Company available for distribution to its stockholders would be distributed among the holders of the shares of common stock, pro rata, based on the number of shares held by each such holder. Common Stock Reserved The Company had the following shares of common stock reserved for future issuance: December 31, 2022 2021 Shares reserved for exercise of outstanding stock options under the 2015 Stock 2,155,577 2,540,963 Shares reserved for exercise of outstanding stock options under the 2021 Stock 1,320,800 496,500 Shares reserved for vesting of restricted stock units granted under the 2021 Stock 219,742 — Shares reserved for future awards under the 2021 Stock Incentive Plan 1,561,034 1,221,593 Shares reserved for issuance under the 2021 Employee Stock Purchase Plan 815,556 566,037 Total shares of common stock reserved 6,072,709 4,825,093 At-the-market equity offering program In March 2022, the Company filed a universal shelf registration statement on Form S-3 to register for sale from time to time up to $ 200.0 million of common stock, preferred stock, debt securities, warrants and/or units in one or more offerings. Further, in March 2022, the Company entered into an Open Market Sale Agreement SM (the “Sales Agreement”) with Jefferies LLC (“Jefferies”) pursuant to which, from time to time, the Company may offer and sell shares of its common stock. Sales of common stock through Jefferies may be made by any method that is deemed an “at-the-market” offering as defined in Rule 415(a)(4) under the Securities Act of 1933, as amended. Jefferies is entitled to compensation at a rate equal to 3.0 % of the gross proceeds from any shares of common stock sold under the Sales Agreement. In August 2022, the Company filed a prospectus supplement under its universal shelf registration for the offer and sale of shares of its common stock having an aggregate offering price up to $ 50.0 million pursuant to the Sales Agreement. As of December 31, 2022, the Company had no t sold any shares of common stock pursuant to the Sales Agreement. Subsequent to December 31, 2022, the Company issued and sold a total of 50,482 shares under the Sales Agreement for aggregate net proceeds of $ 0.2 million after deducting commissions payable by the Company.

Convertible Preferred Stock

Convertible Preferred Stock	12 Months Ended
	Dec. 31, 2022
Temporary Equity Disclosure [Abstract]
Convertible Preferred Stock	10. Convertible Preferred Stock Immediately prior to the closing of its IPO, the Company had an aggregate of 155,398,078 shares of convertible preferred stock issued and outstanding which automatically converted into 16,662,011 shares of common stock upon the closing of its IPO. During the year ended December 31, 2021, in the period prior to the Company’s IPO, $ 2.3 million of cumulative dividends were accrued and unpaid on the Company’s convertible preferred stock. In connection with the completion of the Company’s IPO and the conversion of the outstanding convertible preferred stock into common stock, the $ 2.3 million of accrued and unpaid dividends were eliminated. Subsequent to the closing of the Company’s IPO, no shares of convertible preferred stock were issued or outstanding, and no dividends were accrued.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2021
Share-Based Payment Arrangement [Abstract]
Stock-Based Compensation	11. Stock-Based Compensation 2021 Stock Incentive Plan In connection with its IPO, the Company adopted the 2021 Stock Incentive Plan (the “2021 Plan”), which became effective on February 11, 2021. The 2021 Plan allows the Company to grant stock options, stock appreciation rights, restricted stock, restricted stock units and other stock-based awards to Company’s officers, employees, directors and other key persons (including consultants). The number of shares reserved for issuance under the 2021 Plan will be cumulatively increased each January 1 by 4 % of the number of shares of the Company’s common stock outstanding on the immediately preceding December 31 or such lesser number of shares determined by the Company’s compensation committee. As of December 31, 2021, there were 1,718,093 shares of common stock authorized for issuance under the 2021 Plan and on January 1, 2022, the number of shares of common stock authorized for issuance under the 2021 Plan automatically increased by 998,079 shares. As of December 31, 2022, 1,540,542 shares were reserved for outstanding awards granted under the 2021 Plan and 1,561,034 shares remained available for issuance. Terms of equity grants, including vesting requirements, are determined by the Board or the Compensation Committee of the Board, subject to the provisions of the applicable plan. Shares of common stock may be withheld to satisfy applicable federal, state or local employment tax withholding obligations related to equity awards. Shares of common stock that are tendered to the Company by a participant to exercise an award are added to the number of shares of common stock available for future awards. Upon stock option exercise, the Company issues new shares and delivers them to the participant. 2015 Stock Incentive Plan Prior to the effective date of the 2021 Plan, the Company granted equity awards to eligible employees, officers, directors, consultants and advisors under the 2015 Stock Incentive Plan (the “2015 Plan”). Subsequent to the effective date of the 2021 Plan, no further awards can be made under the 2015 Plan; however, awards outstanding under the 2015 Plan continue to be governed by the 2015 Plan. As of December 31, 2022, there were 2,155,577 shares reserved for outstanding awards granted under the 2015 Plan and no shares remained available for issuance. As of the effective date of the 2021 Plan, the Company will not grant any further awards under the 2015 Plan. Shares that expire, are terminated, repurchased, surrendered or canceled under the 2015 Plan and the 2021 Plan without having been fully exercised are available for future awards under the 2021 Plan. 2021 Employee Stock Purchase Plan In connection with its IPO, the Company adopted the 2021 Employee Stock Purchase Plan (the “2021 ESPP”), which was amended and restated in October 2022. Under the 2021 ESPP, eligible employees are able to purchase shares of common stock at a specified discount. As of December 31, 2021, there were 566,037 shares of common stock authorized for issuance under the 2021 ESPP. On January 1, 2022, the number of shares of common stock authorized for issuance under the 2021 ESPP automatically increased by 249,519 shares. As of December 31, 2022, no shares have been issued under the 2021 ESPP and as such, 815,556 shares remained available for issuance under the 2021 ESPP. Restricted Stock Awards A summary of the Company’s restricted stock activity and related information is as follows: Number of Weighted Unvested as of December 31, 2021 12,537 $ 24.79 Vested ( 12,519 ) 24.80 Canceled/Forfeited ( 18 ) 15.37 Unvested as of December 31, 2022 — $ — No restricted stock awards were issued during the years ended December 31, 2022 or 2021. The aggregate fair value of restricted stock awards that vested during the years ended December 31, 2022 and 2021 was $ 0.3 million and $ 0.6 million, respectively. As of December 31, 2022 , there was no unrecognized compensation cost related to any unvested restricted stock awards. Restricted Stock Units A summary of the Company’s restricted stock unit activity and related information is as follows: Number of Weighted Unvested as of December 31, 2021 — $ — Granted 313,185 3.50 Vested — — Canceled/Forfeited ( 93,443 ) 3.50 Unvested as of December 31, 2022 219,742 $ 3.50 The Company has granted RSUs to certain of its employees under the 2021 Plan, as part of its equity compensation program. Pursuant to the terms of the applicable award agreements, each RSU represents the right to receive one share of the Company’s common stock. All restricted stock units outstanding as of December 31, 2022 will vest, if at all, upon the achievement of specified development milestones associated with the Company’s DB-OTO program, provided the applicable employee remains continuously employed with the Company on the vesting date. Upon vesting, shares of the Company’s common stock will be delivered to the employee, subject to the payment of applicable withholding taxes. As of December 31, 2022, total unrecognized compensation cost related to the unvested restricted stock units was approximately $ 0.8 million, which will not be recognized until it becomes probable that the performance conditions will be met. Stock Options A summary of the Company’s stock option activity and related information is as follows: Number of Weighted Weighted Aggregate (In years) (In thousands) Outstanding as of December 31, 2021 3,037,463 $ 5.34 8.9 $ 629 Granted 1,075,200 Exercised — Cancelled/forfeited ( 636,286 ) Outstanding as of December 31, 2022 3,476,377 $ 4.76 7.4 $ 255 Exercisable as of December 31, 2022 1,671,073 $ 5.13 6.6 $ — Vested and expected to vest as of December 31, 2022 3,476,377 $ 4.76 7.4 $ 255 The Company estimated the fair value of stock options at the date of grant using the Black-Scholes valuation model with the following assumptions: Year Ended December 31, 2022 2021 Risk-free interest rate 1.63 - 4.26 % 0.82 - 1.34 % Expected annual dividend yield 0.00 % 0.00 % Expected stock price volatility 86.7 - 94.1 % 85.4 - 89.3 % Expected term (in years) 5.5 - 6.1 5.0 - 6.1 The weighted-average grant date fair value per share of options granted during the year ended December 31, 2022 and 2021 was $ 2.49 and $ 6.99 , respectively. There were no options exercised during the year ended December 31, 2022. The intrinsic value of options exercised during the year ended December 31, 2021 was $ 0.2 million. As of December 31, 2022 , total unrecognized compensation cost related to the unvested stock options was approximately $ 5.3 million, which is expected to be recognized over a weighted-average period of 2.4 years. Stock-Based Compensation Expense The following table presents the components and classification of stock-based compensation expense (in thousands): Year Ended December 31, 2022 2021 Research and development $ 1,433 $ 1,237 General and administrative 1,767 1,580 Total stock-based compensation expense $ 3,200 $ 2,817 No related income tax benefits were recorded during the years ended December 31, 2022 or 2021 .

Net Loss per Share

Net Loss per Share	12 Months Ended
	Dec. 31, 2022
Earnings Per Share [Abstract]
Net Loss per Share	12. Net Loss per Share Basic and diluted net loss per share attributable to common stockholders was calculated as follows (in thousands, except share and per share amounts) : Year Ended December 31, 2022 2021 Numerator: Net loss $ ( 63,005 ) $ ( 51,823 ) Cumulative dividends on convertible preferred stock — ( 2,309 ) Net loss attributable to common stockholders $ ( 63,005 ) $ ( 54,132 ) Denominator: Weighted-average shares of common stock outstanding, basic and diluted 24,960,008 21,733,960 Net loss per share attributable to common stockholders, basic and diluted $ ( 2.52 ) $ ( 2.49 ) The Company’s potential dilutive securities have been excluded from the computation of diluted net loss per share attributable to common stockholders whenever the effect of including them would be to reduce the net loss per share. In periods where there is a net loss, the weighted average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common stockholders is the same. The following table sets forth the outstanding shares of common stock equivalents, presented based on amounts outstanding at each period end, that were excluded from the calculation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have been anti-dilutive: Year Ended December 31, 2022 2021 Outstanding stock options 3,476,377 3,037,463 Unvested restricted stock units 219,742 — Unvested restricted stock awards — 12,537 Total 3,696,119 3,050,000

License and Collaboration Agree

License and Collaboration Agreement with Regeneron	12 Months Ended
	Dec. 31, 2022
License And Collaboration Agreement With Regeneron [Abstract]
License and Collaboration Agreement with Regeneron	13. License and Collaboration Agreement with Regeneron Agreement Overview In November 2017, the Company entered into the Regeneron Agreement. The Regeneron Agreement had an original research term of five years and granted Regeneron the right to extend the research term for up to two years in one-year intervals. In November 2021, Regeneron exercised its first option to extend the term of the research program through November 2023. Pursuant to the Regeneron Agreement, during the research term, the Company has established research plans that specify the activities each party undertakes with respect to the discovery or development of therapies directed to specific collaboration targets, which are referred to as collaboration products. Each party is responsible for its own respective costs and has agreed to use commercially reasonable efforts to complete the activities as designated in the agreed-upon research plan. Additional collaboration targets may be added to the Regeneron Agreement by mutual consent or if they arise from certain novel target identification activities conducted under the Regeneron Agreement and achieve mutually agreed validation criteria. The Company is primarily responsible for the direction and conduct of the research program. Regeneron is primarily responsible for the contribution of various technologies and expertise of its own as well as contribution of employees and research services. A joint research committee oversees the research program. A joint product committee oversees development and commercialization of a collaboration product following IND acceptance for such collaboration product. As between the parties, the Company is solely responsible for developing and commercializing collaboration products in the field of hearing loss and balance disorders. The Company has an obligation to use commercially reasonable efforts to develop and commercialize such collaboration products in the field. During the term of the Regeneron Agreement, neither the Company nor Regeneron may develop or commercialize any products directed to collaboration targets in the field of treatment and prevention of disease involving loss of hearing or balance, other than pursuant to the Regeneron Agreement. Pursuant to the Regeneron Agreement, Regeneron paid an upfront non-reimbursable fee of $ 25.0 million and purchased 12,500,000 shares of Series B Preferred Stock at price per share of $ 2.00 (see Note 10). If Regeneron elects to extend the term of the research program, it will be obligated to pay $ 10.0 million for each one-year extension. In addition to the upfront payment, the Company is eligible to receive additional milestones through a Phase 2 clinical trial of up to $ 35.5 million in the aggregate if the collaboration product is a biologic or up to $ 33.5 million in the aggregate if the collaboration product is a small molecule. Regeneron contributions are intended to reflect approximately half of the total costs needed to complete a Phase 2 clinical trial. From and after the initiation of a registration enabling trial, unless Regeneron decides to opt-out, the Company has agreed to split development and regulatory costs with Regeneron on an equal basis through the registration enabling trials. Under the Regeneron Agreement, the Company is required to pay Regeneron tiered royalties on the worldwide net sales of collaboration products at percentages which range from mid-single digit to mid-thirties, with the exact royalty rate depending on the extent to which Regeneron shared in the funding of the collaboration product, the level of net sales of the collaboration product, the nature of any intellectual property contributed by Regeneron included in the collaboration product and whether the product is sold inside or outside the field as defined in the Regeneron Agreement. Pursuant to the Regeneron Agreement, the Company has granted to Regeneron a right of first negotiation if it chooses to license or otherwise transfer rights to develop or commercialize collaboration products. Regeneron may opt-out of the collaboration with respect to any collaboration product (i) following submission of the IND to the FDA for a collaboration product, (ii) immediately prior to the initiation of a registration enabling trial, (iii) immediately prior to the submission of a marketing authorization application and (iv) at any time following the initiation of the registration enabling trial, upon notice to the Company within a specified time period. If Regeneron opts out with respect to a collaboration product, it does not owe further milestones on that collaboration product and will no longer share development expenses for such collaboration product. Regeneron may opt back into a collaboration product under certain circumstances. The term of the Regeneron Agreement will continue until neither the Company nor any of its affiliates nor any of its sublicensees are developing or commercializing any collaboration products. Either party may terminate the agreement for cause for the other party’s uncured material breach on prior written notice if the other party becomes insolvent or in certain circumstances in which either party challenges the patent rights of the other party. In October 2020, the Company and Regeneron entered into an amendment to the Regeneron Agreement (the “First Amendment”) pursuant to which, among other things, ATOH1, the target of the DB-ATO program, was removed as a collaboration target and the terms and plans for the DB-OTO and AAV.103 programs were modified. In connection with the First Amendment, the Company issued 10,000,000 shares of Series C Preferred Stock to Regeneron in consideration for its entry into the First Amendment. For the DB-OTO program, the Company also committed to utilize a specified level of research personnel in the program. In addition, upon certain suspensions of development activities for a specified period of time, or if the Company fails to invest specified levels of committed resources to the DB-OTO program, Regeneron would have certain remedies, including the ability to obtain control over further development and commercialization of DB-OTO and AAV.103, subject to payments to the Company to be negotiated, and the ability to terminate its obligations to the Company with respect to other collaboration products. Pursuant to the First Amendment, Regeneron agreed to pay the Company $ 0.3 million to fund the Company’s ongoing research plan and $ 0.5 million to help secure the services of a contract development and manufacturing organization. The $ 0.5 million payment is creditable against the milestone associated with the initiation of manufacturing to support GLP toxicology studies of DB-OTO. Additionally, Regeneron agreed to reimburse the Company for up to $ 10.5 million of third-party costs related to IND-enabling studies for DB-OTO as such costs are incurred, and the Company agreed that the aggregate potential milestone payments for DB-OTO would be reduced by $ 15.0 million. In addition, for DB-ATO, the Company agreed to pay to Regeneron a royalty calculated as a low-to mid-single digit percentage of net sales of DB-ATO, on a country-by-country basis, until the latest of the expiration of the last patent covering DB-ATO in such country, the expiration of all applicable regulatory exclusivities for DB-ATO in such country and the tenth anniversary of the first commercial sale of DB-ATO in such country. In November 2021, Regeneron elected to extend the research term of the collaboration. The research term was extended to November 15, 2023 and Regeneron paid the Company an extension fee of $ 10.0 million. As of December 31, 2022, there was no unbilled accounts receivable to the Company. As of December 31, 2021, the Company had an unbilled accounts receivable of $ 11.4 million related to the remaining balance of reimbursable third-party costs of $ 1.4 million for IND-enabling studies for DB-OTO and $ 10.0 million related to the extension fee resulting from Regeneron exercising its right to extend the research term. Through December 31, 2022 , the Company had received an aggregate of $ 5.5 million in milestone payments from Regeneron pursuant to the collaboration. As of December 31, 2022, the next milestone that the Company was eligible to receive was in relation to the initiation of manufacturing for its AAV.103 program or the initiation of a Phase 1 clinical trial of DB-OTO. In February 2023, the Company entered into a second amendment to the Regeneron Agreement to provide for accelerated milestone payments by Regeneron to the Company for clinical development milestones for DB-OTO and pre-IND milestones for AAV.103 (see Note 17). Accounting Analysis Regeneron Agreement The Company concluded that both the Company and Regeneron were active participants in future research and development activities under the Regeneron Agreement, and both parties were exposed to significant financial risks and rewards dependent on the commercial success of such activities. Further, the Company did not consider Regeneron to be a customer as Regeneron did not transact with the Company to obtain goods and services that were an output of the Company’s ordinary activities in exchange for consideration. Specifically, in this transaction, Regeneron did not receive, and did not have an option to receive, a development and commercialization license from the Company for any collaboration products. Therefore, Regeneron did not have the right to develop and commercialize any of the intellectual property developed under the agreement. Because Regeneron was considered a collaborative partner that was subject to the significant risks and rewards under the agreement, the Company concluded the agreement was within the scope of ASC 808. The Company analogized to the guidance in ASC 606 to determine the measurement and recognition of the consideration received from Regeneron. By analogy to ASC 606, the Company identified its obligations to Regeneron (referred to as performance obligations under ASC 606), determined the amount of consideration to be recognized (referred to as the transaction price under ASC 606) and assessed the pattern of recognition. ASC 606 requires promised goods and services that are both (i) capable of being distinct and (ii) distinct within the context of the contract to be treated as separate performance obligations. Based on the Company’s analysis, the Company’s promised services consisted mainly of (i) research activities related to target discovery and (ii) performing research activities related to certain targets identified during the research program through the submission of an IND. All research activities were considered a single performance obligation because the research activities are interrelated and interdependent as many of the research activities performed benefited the targets. The goal of the parties was to develop as many targets as possible during the research program and therefore the Company’s promised services were not distinct within the context of the contract. The transaction price consisted of the $ 25.0 million upfront payment. Future milestones, which would be considered variable consideration under ASC 606, were highly dependent on the success of the Company’s early stage research activities and therefore were not included in the transaction price until such time as the achievement of such milestone was considered probable. The Company concluded that it satisfied its obligations under the agreement over time as Regeneron received the benefit of the research services as the services were performed. The Company concluded the most appropriate method to track progress towards completion of the performance obligation was an input method that was based on costs incurred. The Company viewed the non-refundable upfront $ 25.0 million payment as reimbursement of the Company’s costs under the agreement which were accounted for as research and development expenses in the Company’s consolidated statement of operations and comprehensive loss. Further, while Regeneron is a related party (see Note 16), there was no presumption that the Company would reimburse Regeneron for the upfront payment as the amounts represented a reimbursement for research and development costs incurred and there were no terms or conditions that would require repayment. As such, the upfront payment is being recognized as a reduction to research and development expense (contra-research and development expense) in the Company’s consolidated statements of operations and comprehensive loss based on the Company’s progress towards completion of its research activities under the research plan. Consideration to be received from Regeneron relating to the DB-OTO clinical development milestones will begin to be recognized over time once the achievement of each clinical development milestone is deemed probable. Consideration will be measured using an input method based on costs incurred to date relative to total cost. The Company's promised services are the development services under the development plan through a registration-enabling study or submission of a marketing authorization application. All development services are considered a single performance obligation being performed under the development plan. The Company will continue to monitor the likelihood of achievement of each clinical development milestone and will remove the respective constraints when achievement is deemed probable. The Company will recognize a cumulative catch-up adjustment when the constraint is removed, which will be calculated as the respective milestone payment multiplied by the measure of progress at that time. First Amended Agreement The Company concluded that both the Company and Regeneron remain active participants in the research and development activities under the First Amended Agreement, both parties remain exposed to significant financial risks and rewards dependent upon the commercial success of such activities, and Regeneron does not meet the definition of a customer under ASC 606. Specifically, Regeneron did not receive in the Amended Agreement, and continued to not have an option to receive, a development and commercialization license from the Company for any collaboration products. Therefore, Regeneron continues to not have the right to develop and commercialize any of the intellectual property developed under the Amended Agreement. Accordingly, the Company concluded the Amended Agreement is within the scope of ASC 808 and the Company continues to apply ASC 606 by analogy to account for the Amended Agreement. As such, the Company analogized to the contract modification guidance in ASC 606 to account for the scope and pricing changes contained in the Amended Agreement. The Company concluded the performance obligation under the Amended Agreement, continues to be a single performance obligation and the remaining services under the Amended Agreement are not distinct from those already provided. Therefore, the Company accounted for the modification by updating the transaction price and measure of progress prospectively with a cumulative catch-up entry recorded as of the effective date of the Amended Agreement. As of December 31, 2022, t he transaction price of $ 46.9 million consists of (i) $ 25.0 million received upfront, (ii) $ 0.3 million received to fund the ongoing research plan, (iii) $ 5.5 million of aggregate milestones achieved, (iv) $ 10.5 million in reimbursements for third-party costs related to IND-enabling studies for DB-OTO, and (v) $ 10.0 million as consideration for Regeneron’s election to extend the research term, partially offset by the fair value of the Series C convertible preferred stock issued to Regeneron of approximately $ 4.4 million. The Company concluded the issuance of Series C Preferred Stock should be accounted for consistent with consideration paid to a customer and is therefore a reduction of the transaction price under the Amended Agreement. The Company accounted for Regeneron’s exercise of its right to extend the research term for an additional year as a contract modification. The extension did not change the scope of the Company’s obligations under the Amended Agreement. The Company updated the transaction price to include the $ 10.0 million extension fee and measure of progress to reflect the extended research term. Following Regeneron’s extension in November 2021, the updated transaction price under the collaboration is $ 46.9 million. Future milestones continue to be fully constrained until such time as the achievement of such milestones are considered probable. The Company concluded that it continues to satisfy its obligations over time as Regeneron receives the benefit of the research services as the services are performed and the most appropriate method to track progress towards completion of the performance obligation is an input method that is based on costs incurred. There are significant judgments and estimates inherent in the determination of the costs to be incurred for the research and development activities related to the collaboration with Regeneron. These estimates and assumptions include a number of objective and subjective factors, including the likelihood that a target will be successfully developed through its IND filing and the estimated costs associated with such development, including the potential third-party costs related to each target’s IND-enabling study. The Company recognized $ 8.4 million and $ 11.0 million of contra-research and development expense for the years ended December 31, 2022 and 2021, respectively. As of December 31, 2022 and 2021 , there was $ 9.4 million and $ 8.1 million of deferred collaboration liability classified in current liabilities, respectively, and $ 6.8 million and $ 16.4 million of deferred collaboration liability classified in long-term liabilities, respectively.

Employee Retirement_Savings Pla

Employee Retirement/Savings Plan	12 Months Ended
	Dec. 31, 2022
Retirement Benefits [Abstract]
Employee Retirement/Savings Plan	14. Employee Retirement/Savings Plan The Company maintains an employee retirement/savings plan (the “Retirement Plan”) that permits participants to make tax-deferred contributions by salary reduction pursuant to Section 401(k) of the Internal Revenue Code. For the years ended December 31, 2022 and 2021 the Company provided a matching contribution to the Retirement Plan based on a match formula of 100 % up to 3 %, and 50 % of the next 2 % or a maximum match of 4 %. The Company made matching contributions of $ 0.5 million and $ 0.3 million for the years ended December 31, 2022 and 2021, respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Income Taxes	15. Income Taxes During the year ended December 31, 2022, the Company recorded $ 0.2 million of income tax expense, primarily related to the recording of income tax expense for the Company’s Australian subsidiary. During the year ended December 31, 2021, the Company recorded $ 1.8 million of income tax expense, which was primarily driven by the recording of an uncertain tax position and additional income tax expense for the Australian subsidiary. For financial reporting purposes, loss before provision for income taxes, includes the following components (in thousands): Year Ended December 31, 2022 2021 Domestic $ ( 62,859 ) $ ( 50,825 ) Foreign 94 799 Loss before income taxes $ ( 62,765 ) $ ( 50,026 ) The provision (benefit) for income taxes consists of the following (in thousands): Year Ended December 31, 2022 2021 Current: Federal $ — $ — State 13 — Foreign 227 1,797 Total Current 240 1,797 Deferred: Federal — — State — — Foreign — — Total Deferred — — Loss before income taxes $ 240 $ 1,797 A reconciliation of the expected income tax (benefit) computed using the federal statutory income tax rate to the Company’s effective income tax rate is as follows: Year Ended December 31, 2022 2021 Expected income tax benefit at the federal statutory rate 21.0 % 21.0 % State taxes, net 5.9 5.8 Foreign taxes — ( 0.5 ) Change in valuation allowance ( 28.6 ) ( 27.2 ) Research and development tax credits 3.2 0.7 Rate differential on foreign operations — ( 0.1 ) Stock compensation ( 0.9 ) ( 0.5 ) Uncertain Tax Position — ( 2.9 ) Permanent differences ( 0.5 ) 0.1 Other ( 0.5 ) — Effective income tax rate ( 0.4 )% ( 3.6 )% Deferred taxes are recognized for temporary differences between the basis of assets and liabilities for financial statement and income tax purposes. The significant components of the Company’s deferred tax assets and liabilities consisted of the following (in thousands): December 31, 2022 2021 Deferred tax assets: Federal, state and foreign net operating loss carryforwards $ 59,068 $ 53,075 Research and development and other credits 3,835 1,840 Lease liability 3,800 — Capitalized research and development expenses 9,998 — Deferred rent and lease incentive obligation — 1,321 Accrued expenses and other 1,428 1,551 Total gross deferred tax assets 78,129 57,787 Valuation allowance ( 74,926 ) ( 57,013 ) Total deferred tax assets $ 3,203 $ 774 Deferred tax liabilities: Right of use assets ( 2,679 ) — Depreciation of fixed assets ( 524 ) ( 774 ) Total deferred tax liabilities $ ( 3,203 ) $ ( 774 ) Net deferred taxes $ — $ — The Company evaluated the positive and negative evidence bearing upon its ability to realize the deferred tax assets as of December 31, 2022 and 2021. Management considered the Company’s cumulative net losses and concluded as of December 31, 2022 and 2021 that it was more likely than not that the Company would not realize the benefits of the deferred tax assets. Accordingly, a full valuation allowance was established against the net deferred tax assets as of December 31, 2022 and 2021. Changes in the valuation allowance for deferred tax assets were as follows (in thousands): Year Ended December 31, 2022 2021 Valuation allowance at beginning of the year $ 57,013 $ 44,305 Increases recorded to income tax provision 17,913 12,708 Valuation allowance at end of year $ 74,926 $ 57,013 Subject to the limitations described below, as of December 31, 2022 and 2021, the Company had U.S. federal net operating loss carryforwards of approximately $ 217.9 million and $ 196.3 million, respectively, to offset future federal taxable income. Federal net operating losses of $ 41.7 million will expire beginning in 2033 . As of December 31, 2022, the Company had net operating losses of $ 176.2 million which had an indefinite life. As of December 31, 2022 and 2021, the Company had state net operating loss carryforwards of approximately $ 210.5 million and $ 187.9 million, respectively, to offset future state taxable income, which will begin to expire in 2035 . Subject to the limitations described below, at December 31, 2022 and 2021, the Company had federal research and development tax credit carryforwards of $ 1.9 million and $ 1.2 million, respectively, which expire beginning in 2033 . The Company also had $ 1.3 million of Orphan Drug credit carryforwards, which expire beginning in 2043 . As of December 31, 2022 and 2021, the Company had state research and development tax credit carryforwards of $ 0.9 million and $ 0.8 million, respectively, which expire beginning in 2032 . The Company has generated federal and state research and development credits but has not conducted a study to document the qualified activity. This study may result in an adjustment to the Company’s research and development credit carryforwards; however, until a study is completed, and any adjustment is known, no amounts are being presented as an uncertain tax position. A full valuation allowance has been provided against the Company’s research and development credits and, if an adjustment is required, this adjustment would be offset by an adjustment to the deferred tax asset established for the research and development credit carryforwards and the valuation allowance. Under the provisions of the Internal Revenue Code, the net operating loss and tax credit carryforwards are subject to review and possible adjustment by the Internal Revenue Service (“IRS”) and state tax authorities. Net operating loss and tax credit carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant shareholders over a three-year period in excess of 50 %, as defined under Sections 382 and 383 of the Internal Revenue Code, respectively, as well as similar state provisions. This could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities. The amount of the annual limitation is determined based on the value of the Company immediately prior to the ownership change. Subsequent ownership changes may further affect the limitation in future years. The Company has not conducted a study to assess whether a change of control has occurred or whether there have been multiple changes of control since inception due to the significant complexity and cost associated with such a study. If the Company has experienced a change of control, as defined by Section 382 of the Internal Revenue Code, at any time since inception, utilization of the net operating loss carryforwards or research and development tax credit carryforwards would be subject to an annual limitation under Section 382 of the Internal Revenue Code, which is determined by first multiplying the value of the Company’s stock at the time of the ownership change by the applicable long-term-tax-exempt rate, and then could be subject to additional adjustments, as required. Any limitations may result in expiration of a portion of the net operating loss carryforwards or research and development tax credit carryforwards before utilization. Further, until a study is completed by the Company and any limitation is known, no amounts are being presented as an uncertain tax position. We assess the impact of various tax reform proposals and modifications to existing tax treaties in all jurisdictions where we have operations to determine the potential effect on our business and any assumptions we have made about our future taxable income. We cannot predict whether any specific proposals will be enacted, the terms of any such proposals or what effect, if any, such proposals would have on our business if they were to be enacted. Beginning in 2022, the Tax Cuts and Jobs Act of 2017 eliminates the currently available option to deduct research and development expenditures and requires taxpayers to amortize them over five years . The U.S. Congress is considering legislation that would defer the amortization requirement to future periods, however, we have no assurance that the provision will be repealed or otherwise modified. The Company files income tax returns in the United States, Australia and Massachusetts. The statute of limitations for assessment by the IRS and state tax authorities is closed prior to 2018, although carryforward attributes that were generated prior to tax year 2019 may still be adjusted upon examination by the IRS or state tax authorities if they either have been or will be used in a future period. The Company is currently not under examination by the IRS or any other jurisdictions for any tax years. The statute of limitations for assessment by the Australian Taxation Office is four years from the date of return filing. The Company is not currently under examination by the Australian Taxation Office for any tax years. The Company establishes reserves for uncertain tax positions based on management’s assessment of exposures associated with tax positions taken on tax return filings. The tax reserves are analyzed periodically, and adjustments are made as events occur to warrant adjustments to the reserve. As of December 31, 2022, the Company had $ 1.6 million of gross unrecognized tax benefits, of which $ 1.4 million would affect income tax expense if recognized, before consideration of the Company’s valuation allowance. As of December 31, 2022, the gross unrecognized tax benefits included $ 0.2 million of deferred tax asset previously offset by a full valuation allowance. The Company does not expect the unrecognized tax benefits to change significantly over the next 12 months. The Company recognizes both interest and penalties associated with uncertain tax positions as a component of income tax expense. The Company has accrued penalties and provisions for interest of $ 0.5 million and $ 0.4 million as of December 21, 2022 and 2021, respectively. A reconciliation of the gross unrecognized tax benefits are as follows (in thousands): Year Ended December 31, 2022 2021 Unrecognized tax benefits at the beginning of the period $ 2,084 $ — Increases for current tax positions — 2,084 Reductions related to previous tax positions ( 85 ) — Reductions related to translation adjustments ( 369 ) — Unrecognized tax benefits at the end of the period $ 1,630 $ 2,084

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2022
Related Party Transactions [Abstract]
Related Party Transactions	16. Related Party Transactions As of December 31, 2022, Regeneron held 2,097,314 shares of common stock, approximately 8.4 % of common stock outstanding as of that date. During the years ended December 31, 2022 and 2021, the Company recognized $ 8.4 million and $ 11.0 million as a reduction to research and development expense (contra-research and development) based on progress towards completion of its research activities under the research plan for its license and collaboration agreement with Regeneron in its consolidated statements of operations and comprehensive loss. As of December 31, 2022, the Company had no unbilled accounts receivables due from Regeneron. As of December 31, 2021, the Company had $ 11.4 million of unbilled accounts receivables due from Regeneron (see Note 13). As of December 31, 2022 and 2021, the Company did no t have any amounts due to Regeneron. For the years ended December 31, 2022 and 2021, the Company recorded no expenses and $ 0.2 million of expenses, respectively, relating to consulting services provided by an entity affiliated with a stockholder of the Company and a member of the Company’s Board of Directors. The Company terminated this arrangement effective December 31, 2021. As of December 31, 2022, the Company had no further amounts due to this entity. As of December 31, 2021, the Company had $ 0.2 million due to this entity, which was subsequently paid during the three months ended March 31, 2022.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2022
Subsequent Events [Abstract]
Subsequent Events	17. Subsequent Events The Company considers events and transactions that occur after the balance sheet date but prior to the issuance of the consolidated financial statements for potential recognition or disclosure in the consolidated financial statements. In February 2023, the Company entered into a second amendment with Regeneron to provide for accelerated development milestone payments by Regeneron to the Company for clinical development milestones for DB-OTO and pre-IND milestones for AAV.103. Subsequent to December 31, 2022, the Company issued and sold a total of 50,482 shares under the Sales Agreement for aggregate net proceeds of $ 0.2 million after deducting commissions payable by the Company. On Friday, March 10, 2023, the Federal Deposit Insurance Corporation (“FDIC”) announced that Silicon Valley Bank (“SVB”) was closed and that the FDIC was appointed as receiver. As of March 10, 2023, the Company had three cash deposit accounts at SVB, each with a balance less than or equal to $250,000. The Company also had, as of March 10, 2023, approximately $4.0 million in a money market account at a separate independent financial institution for which SVB acted solely as custodian. The Company’s other cash resources are held in custody accounts at separate independent financial institutions. On Sunday March 12, 2023, the Secretary of the Treasury, the Federal Reserve Board Chair and the FDIC Chairman issued a joint statement announcing the approval of actions enabling the FDIC to complete its resolution of SVB in a manner that fully protects all depositors. The Company will continue to monitor this evolving situation and is evaluating alternative commercial banking options.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation These consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASUs”) of the Financial Accounting Standards Board (“FASB”).
Principles of Consolidation	Principles of Consolidation The accompanying consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries, Decibel Securities Corporation and Decibel Therapeutics Australia Pty. All intercompany balances and transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts in the financial statements and accompanying notes. Actual results could materially differ from those estimates. Management considers many factors in selecting appropriate financial accounting policies and controls, and in developing the estimates and assumptions that are used in the preparation of these consolidated financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates, including expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes and management must select an amount that falls within that range of reasonable estimates. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, the estimated cost to perform research which is an input into the measurement of research and development expenses recognized under the Company’s collaboration agreement with Regeneron Pharmaceuticals, Inc. (“Regeneron”) , the accrual of research and development expenses, stock-based compensation expenses, leases and income taxes. Estimates are periodically reviewed considering changes in circumstances, facts and historical experience. Actual results may differ from the Company’s estimates.
Segment Information	Segment Information Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision-maker in deciding how to allocate resources and assess performance. The Company and the Company’s chief operating decision-maker, the Company’s chief executive officer, view the Company’s operations and manages its business as a single operating segment. All of the Company’s long-lived assets are held in the United States.
Cash, Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted Cash Cash equivalents are short-term, highly liquid investments that are readily convertible into cash, with original maturities of three months or less. Cash equivalents are mainly comprised of money market accounts invested in U.S. Treasury securities and agency bonds. Restricted cash is comprised of deposits with a financial institution used to collateralize letters of credit related to the Company’s lease arrangements. Restricted cash is presented as a component of prepaid expenses and other current assets and other assets on the consolidated balance sheets. Cash, cash equivalents and restricted cash consisted of the following (in thousands): December 31, 2022 2021 Cash and cash equivalents $ 34,607 $ 36,455 Restricted cash, current 38 — Restricted cash, long-term 924 1,128 Total cash, cash equivalents and restricted cash as shown on the statement $ 35,569 $ 37,583
Available-For-Sale Securities	Available-For-Sale Securities The Company classifies all of its investments as available-for-sale securities and reports them at fair value using quoted prices in active markets for similar securities. Unrealized gains and losses on available-for-sale securities are reported as accumulated other comprehensive loss, which is a separate component of stockholders’ equity. The cost of securities sold is determined on a specific identification basis, and realized gains and losses are included in other income (expense), net within the consolidated statements of operations and comprehensive loss. The Company regularly reviews all of its investments for other-than-temporary declines in estimated fair value. The Company’s review includes the consideration of the cause of the impairment, including the creditworthiness of the security issuers, the number of securities in an unrealized loss position, the severity and duration of the unrealized losses, whether the Company has the intent to sell the securities and whether it is more likely than not that the Company will be required to sell the securities before the recovery of their amortized cost basis. When the Company determines that the decline in estimated fair value of an investment is below the amortized cost basis and the decline is other-than-temporary, the Company reduces the carrying value of the security and records a loss for the amount of such decline. No such adjustments were necessary during the periods presented. The Company classifies its available-for-sale securities as current assets on the consolidated balance sheets if they mature within one year from the balance sheet date, and long-term available-for-sale securities if they mature longer than one year from the balance sheet date.
Concentrations of Credit Risk and Significant Suppliers	Concentrations of Credit Risk and Significant Suppliers Financial instruments that potentially expose the Company to credit risk primarily consist of cash, cash equivalents, restricted cash and available-for-sale securities. The Company maintains its cash, cash equivalents, restricted cash and available-for-sale securities balances with accredited financial institutions and, consequently, the Company does not believe it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships. The Company’s cash management and investment policy limits investment instruments to U.S. Treasury and government securities with the objective to preserve capital and to maintain liquidity until the funds can be used in business operations. Bank accounts in the United States are insured by the Federal Deposit Insurance Corporation (“FDIC”) up to $ 250,000 . As of December 31, 2022 and 2021, the Company’s primary operating accounts significantly exceeded the FDIC limits. 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, other raw materials and formulated drugs related to these programs. These programs could be adversely affected by a significant interruption in the supply of active pharmaceutical ingredients, other raw materials and formulated drugs.
Off-Balance Sheet Arrangements	Off-Balance Sheet Arrangements As of December 31, 2022, and 2021 , the Company had no off-balance sheet arrangements, as defined in the rules and regulations of the SEC.
Fair Value Measurements	Fair Value Measurements Certain assets and liabilities of the Company are carried at fair value under GAAP. The fair values of the Company’s financial assets and liabilities reflect the Company’s estimate of the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: • Level 1—Quoted prices in active markets for identical assets or liabilities. • Level 2—Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. • Level 3—Unobservable inputs that are supported by little or no market activity that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. To the extent the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The carrying amounts reflected in the consolidated balance sheets for cash, accounts receivable, prepaid expenses and other current assets, accounts payable and accrued expenses approximate their fair values due to the short-term nature of these assets and liabilities. Items measured at fair value on a recurring basis include cash equivalents and available-for-sales securities as of December 31, 2022 and 2021 .
Accounts Receivable, Net	Accounts Receivable, net The Company records accounts receivable for amounts invoiced to a collaborator, for which the Company has an unconditional right to consideration. For amounts to which the Company has an unconditional right to consideration but has not yet invoiced the collaborator, the Company records unbilled accounts receivable. The Company assesses the collectability for its accounts receivable and unbilled accounts receivable and records an allowance as deemed necessary. As of December 31, 2022 and 2021 , no allowance was recorded. Accounts receivable and unbilled accounts receivable are presented in accounts receivable, net on the consolidated balance sheets.
Property and Equipment	Property and Equipment Property and equipment is stated at cost, net of accumulated depreciation and amortization. Depreciation and amortization are calculated using the straight-line method over the estimated useful lives of the assets, which are as follows: Estimated Useful Life Computer equipment and software 3 years Furniture and fixtures 7 years Laboratory equipment 5 years Leasehold improvements Shorter of useful life or remaining lease term Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation and amortization are removed from the accounts and any resulting gain or loss is included in income (loss) from operations. Expenditures for repairs and maintenance that do not improve or extend the lives of the respective assets are charged to expense as incurred, while costs of major additions and betterments are capitalized.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets The Company periodically evaluates its long-lived assets, which consist of property and equipment, for impairment whenever events or changes in circumstances indicate that a potential impairment may have occurred. If such events or changes in circumstances arise, the Company compares the carrying amount of the long-lived assets to the estimated future undiscounted cash flows expected to be generated by the long-lived assets. If the estimated aggregate undiscounted cash flows are less than the carrying amount of the long-lived assets, an impairment charge, calculated as the amount by which the carrying amount of the assets exceeds the estimated fair value of the assets, is recorded. The estimated fair value of the long-lived assets is determined based on the estimated discounted cash flows expected to be generated from the long-lived assets.
Research and Development Costs and Accruals	Research and Development Costs and Accruals Research and development costs are expensed as incurred. Research and development expenses are comprised of costs incurred in performing research and development activities, including salaries, stock-based compensation and benefits, laboratory supplies, depreciation on and maintenance of research equipment, manufacturing expenses and external costs of outside vendors engaged to conduct preclinical and clinical development activities and the allocable portions of facility costs, such as rent, utilities, repairs and maintenance, depreciation, and general support services. Additionally, the consideration the Company receives under its license and collaboration agreement with Regeneron is being recognized as a reduction to research and development expense (contra-research and development expense) in the Company’s consolidated statements of operations and comprehensive loss based on the Company’s progress towards completion of its research activities under the research plan (see Note 13). Upfront payments and milestone payments made for the licensing of technology are expensed as research and development expenses in the period in which they are incurred. Nonrefundable advance payments for goods or services to be received in the future for use in research and development activities are recorded as prepaid expenses. The prepaid amounts are expensed as the related goods are delivered or the services are performed. The Company records accruals for estimated ongoing research and development costs. When evaluating the adequacy of the accrued liabilities, the Company analyzes progress of the preclinical studies or clinical trials, including the phase or completion of events, invoices received and contracted costs. Significant judgments and estimates are made in determining the accrued balances at the end of any reporting period. Actual results could differ from the Company’s estimates. The Company’s historical accrual estimates have not been materially different from the actual costs.
Patent Costs	Patent Costs All patent-related costs incurred in connection with filing, maintaining and prosecuting patent applications are expensed as incurred due to the uncertainty about the recovery of the expenditure. Amounts incurred are classified as general and administrative expenses.
Stock-Based Compensation	Stock-Based Compensation The Company issues stock-based awards to employees, directors and non-employee consultants, generally in the form of stock options, restricted stock and restricted stock units (“RSUs”). The Company accounts for its stock-based compensation awards in accordance with FASB ASC Topic 718, Compensation—Stock Compensation (“ASC 718”). ASC 718 requires stock-based payments to employees, qualifying directors and non-employees to be recognized as expense based on the fair value determined on the date of grant. The Company issues equity awards with service-based and performance-based vesting conditions. Compensation expense related to awards to employees, directors and non-employees with service-based vesting conditions is recognized on a straight-line basis based on the grant date fair value over the associated requisite service period of the award, which is generally the vesting term. Compensation expense related to awards to employees, directors and non-employees with performance-based vesting conditions is recognized when it becomes probable that the performance conditions will be met using the accelerated attribution method. The Company has no awards with market-based conditions. The Company recognizes forfeitures as they occur. The Company classifies stock-based compensation expense in the consolidated statements of operations and comprehensive loss in the same manner in which the award recipient’s salary and related costs are classified or in which the award recipient’s service payments are classified, as applicable. The Company determines the fair value of restricted stock and RSU awards in reference to the fair value of its common stock less any applicable purchase price. The Company estimates the fair value of its stock options using the Black-Scholes option pricing model, which requires inputs of subjective assumptions, including: (i) the expected volatility of its common stock, (ii) the expected term of the award, (iii) the risk-free interest rate, (iv) expected dividends and (v) the fair value of its common stock. Due to the lack of a public market for the trading of its common stock prior to the completion of its IPO and a lack of company-specific historical and implied volatility data, the Company bases the estimate of expected volatility on the historical volatilities of a representative group of publicly traded companies. For these analyses, the Company selects companies with comparable characteristics and with historical share price information that approximates the expected term of the stock-based awards. The Company computes the historical volatility data using the daily closing prices for the selected companies’ shares during the equivalent period that approximates the calculated expected term of its stock options. The Company will continue to apply this method until a sufficient amount of historical information regarding the volatility of its own stock price becomes available. The Company estimates the expected term of its stock options granted to employees and directors using the simplified method, whereby the expected term equals the average of the vesting term and the original contractual term of the option. The Company utilizes this method as it does not have sufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term. The expected dividend yield is assumed to be zero, as the Company has no current plans to pay any dividends on its common stock. The Company has elected to use the expected term for stock options granted to non-employees, using the simplified method, as the basis for the expected term assumption. However, the Company may elect to use either the contractual term or the expected term for stock options granted to non-employees on an award-by-award basis. Subsequent to the completion of the IPO, the fair value of the common stock underlying the Company’s stock-based awards is determined based on the trading price of its common stock on the Nasdaq Global Select Market on the date of grant.
Leases	Leases The Company adopted FASB ASU No. 2016-02, Leases (“ASC 842”), effective January 1, 2022 using the required modified retrospective approach and utilizing the effective date as its date of initial application. Prior periods are presented in accordance with previous guidance in FASB ASC Topic 840, Leases. The Company evaluates whether an arrangement is or contains a lease at contract inception. If a contract is or contains a lease, lease classification is determined at lease commencement, which represents the date at which the underlying asset is made available for use by the Company. The Company’s lease terms are generally measured as the respective lease’s noncancelable term and exclude any optional extension terms as the Company is not reasonably certain to exercise such options. The Company elected the short-term lease exemption and therefore does not recognize lease liabilities and right-of-use assets for lease arrangements with original lease terms of twelve months or less. Lease liabilities represent the Company’s obligation to make lease payments under a lease arrangement. Lease liabilities are measured as the present value of fixed lease payments, discounted using an incremental borrowing rate, as interest rates implicit in the Company’s lease arrangements are generally not readily determinable. The Company elected the practical expedient to not separate lease and non-lease components for its real estate leases and therefore both are considered when determining the lease payments in a lease arrangement. Variable lease costs are expensed as incurred. The incremental borrowing rate represents the interest rate at which the Company could borrow a fully collateralized amount equal to the lease payments, over a similar term, in a similar economic environment. The Company determines the incremental borrowing rate at lease commencement, generally using a synthetic credit rating based on the Company’s financial position and negative cash flows, factoring in adjustments for additional risks based on the Company’s economic condition, a survey of comparable companies with similar credit and financial profiles, as well as additional market risks, as may be applicable. Right-of-use assets represent the Company’s right to use an underlying asset over its lease term. Right-of-use assets are initially measured as the associated lease liability, adjusted for prepaid rent and tenant incentives. The Company remeasures right-of-use assets and lease liabilities when a lease is modified, and the modification is not accounted for as a separate contract. A modification is accounted for as a separate contract if the modification grants the Company an additional right of use not included in the original lease agreement and the increase in lease payments is commensurate with the additional right of use. The Company assesses its right-of-use assets for impairment consistent with its policy for impairment of long-lived assets held and used in operations.
Income Taxes	Income Taxes Income taxes are recorded in accordance with FASB ASC Topic 740, Income Taxes (“ASC 740”), which provides for deferred taxes using an asset and liability approach. The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the consolidated financial statements or tax returns. Deferred tax assets and liabilities are determined based on the difference between the consolidated financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The Company assesses the likelihood that its deferred tax assets will be recovered from future taxable income and, to the extent it believes, based upon the weight of available evidence, that it is more likely than not that all or a portion of the deferred tax assets will not be realized, a valuation allowance is established through a charge to income tax expense. Potential for recovery of deferred tax assets is evaluated by estimating the future taxable profits expected and considering prudent and feasible tax planning strategies. Should the actual amounts differ from these estimates, the amount of the Company’s valuation allowance could be materially impacted. Changes in these estimates may result in significant increases or decreases to the tax provision in a period in which such estimates are changed, which in turn would affect net income or loss. The Company accounts for uncertainty in income taxes recognized in the consolidated financial statements by applying a two-step process to determine the amount of tax benefit to be recognized. First, the tax position must be evaluated to determine the likelihood that it will be sustained upon external examination by the taxing authorities. If the tax position is deemed more-likely-than-not to be sustained, the tax position is then assessed to determine the amount of benefit to recognize in the consolidated financial statements. The amount of the benefit that may be recognized is the largest amount that has a greater than 50% likelihood of being realized upon ultimate settlement. Derecognition of a tax position that was previously recognized occurs when the Company subsequently determines that a tax position no longer meets the more likely than not threshold. To the extent an income tax provision is necessary, the provision for income taxes would include the effects of any resulting tax reserves, or unrecognized tax benefits, that are considered appropriate as well as the related net interest and penalties. The provision for income taxes includes the effects of any resulting tax reserves or unrecognized tax benefits that are considered appropriate as well as the related net interest and penalties.
Comprehensive Loss	Comprehensive Loss Comprehensive loss includes net loss as well as other changes in stockholders’ equity that result from transactions and economic events other than those with stockholders. Other comprehensive loss for all periods presented consists solely of unrealized gains (losses) on available-for-sale securities.
Revenue Recognition	Revenue Recognition The Company recognizes revenue from contracts with customers under FASB ASC Topic 606, Revenue from Contracts with Customers (“ASC 606”). The Company has not had any transactions that fall within the scope of ASC 606, but does use ASC 606 by analogy for the measurement and recognition of contra-research and development expense under its collaboration agreement, which is accounted for under FASB ASC Topic 808, Collaborative Agreements (“Topic 808”). Under ASC 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the entity expects to receive in exchange for those goods or services. To determine the appropriate amount of revenue to be recognized for arrangements determined to be within the scope of ASC 606, the Company will perform the following five steps: (i) identification of the contract(s) with the customer, (ii) identification of the promised goods or services in the contract and determination of whether the promised goods or services are performance obligations, (iii) measurement of the transaction price, (iv) allocation of the transaction price to the performance obligations and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. The Company will account for a contract with a customer that is within the scope of ASC 606 when all of the following criteria are met: (i) the arrangement has been approved by the parties and the parties are committed to perform their respective obligations, (ii) each party’s rights regarding the goods or services to be transferred can be identified, (iii) the payment terms for the goods or services to be transferred can be identified, (iv) the arrangement has commercial substance and (v) collection of substantially all of the consideration to which the Company will be entitled in exchange for the goods or services that will be transferred to the customer is probable. The Company estimates the transaction price based on the amount of consideration the Company expects to be received for transferring the promised goods or services in the contract. The consideration may include both fixed consideration and variable consideration. For each arrangement that includes variable consideration, the Company evaluates the amount of the potential payments and the likelihood that the payments will be received. The Company utilizes either the most likely amount method or expected value method to estimate the transaction price based on which method better predicts the amount of consideration expected to be received. If it is probable that a significant revenue reversal would not occur, the variable consideration is included in the transaction price. For arrangements that include development and regulatory milestone payments, the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company’s control or the licensee’s control, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. At the end of each reporting period, the Company re-evaluates the probability of achievement of such milestones and any related constraint, and if necessary, adjusts the estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect collaboration revenue and net loss in the period of adjustment. For sales-based royalties, including milestone payments based on the level of sales, the Company determines whether the sole or predominant item to which the royalties relate is a license. When the license is the sole or predominant item to which the sales-based royalty relates, the Company recognizes revenue at the later of: (i) when the related sales occur or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). The Company allocates the transaction price to each performance obligation based on the relative estimated standalone selling price of the performance obligations. The Company must develop assumptions that require judgment to determine the standalone selling price for each performance obligation identified in the contract. The Company utilizes key assumptions to determine the standalone selling price, which may include other comparable transactions, pricing considered in negotiating the transaction and the estimated costs. Certain variable consideration is allocated specifically to one or more performance obligations in a contract when the terms of the variable consideration relate to the satisfaction of the performance obligation and the resulting amounts allocated to each performance obligation are consistent with the amounts the Company would expect to receive for each performance obligation. For performance obligations which consist of licenses and other promises, the Company utilizes judgment to assess the nature of the combined performance obligation in order to determine whether the combined performance obligation is satisfied over time or at a point in time. The Company determines the appropriate method of measuring progress of combined performance obligations satisfied over time for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. If the license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company will recognize revenue from non-refundable, upfront fees allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the license.
Collaboration Agreements	Collaboration Agreements The Company analyzes its collaboration arrangements to assess whether they are within the scope of Topic 808 to determine whether such arrangements involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards that are dependent on the commercial success of such activities. To the extent the arrangement is within the scope of Topic 808, the Company assesses whether aspects of the arrangement between the Company and its collaboration partner are within the scope of other accounting literature, including ASC 606. If it is concluded that some or all aspects of the arrangement represent a transaction with a customer, the Company will account for those aspects of the arrangement within the scope of ASC 606. Pursuant to ASC 606, a customer is a party that has contracted with an entity to obtain goods or services that are an output of the entity’s ordinary activities in exchange for consideration. Under ASC 606, an entity recognizes revenue when its customer obtains control of promised goods or services in an amount that reflects the consideration which the entity expects to receive in exchange for those goods or services. ASC 808 provides guidance for the presentation and disclosure of transactions in collaborative arrangements, but it does not provide recognition or measurement guidance. Therefore, if the Company concludes a counterparty to a transaction is not a customer or otherwise not within the scope of ASC 606, the Company considers the guidance in other accounting literature, including the guidance in ASC 606, as applicable or by analogy to account for such transaction. The classification of transactions under the Company’s arrangements is determined based on the nature and contractual terms of the arrangement along with the nature of the operations of the participants. To date, the Company has entered into a collaboration agreement with Regeneron (see Note 13).
CARES Act	CARES Act The CARES Act provided refundable employee retention credits, which could be used to offset payroll tax liabilities. On March 11, 2021, President Biden signed the American Rescue Plan Act (“ARPA”). The ARPA includes several provisions, such as measures that extend and expand the employee retention credit, previously enacted under the CARES Act, through December 31, 2021. Measures not related to income-based taxes within the CARES Act include (1) allowing an employer to pay its share of Social Security payroll taxes that would otherwise be due from the date of enactment through December 31, 2020 over the following two years and (2) allowing eligible employers subject to closure due to the COVID-19 pandemic to receive a 50% credit on qualified wages against their employment taxes each quarter, with any excess credits eligible for refunds. The Company accounts for the grant under ASU No. 2021-10, Government Assistance (Topic 832): Disclosures by Business Entities about Government Assistance (“ASU 2021-10”). During the year ended December 31, 2021, the Company recorded an employee retention credit of $ 0.9 million upon completion of an analysis providing reasonable assurance that it met the conditions set forth in the CARES Act and it was reasonably assured that it will receive the employee retention credit. The employee retention credit was recorded in research and development expenses and general and administrative expenses in the manner in which the qualified wages and related costs were classified. No such additional amounts were recorded during the year ended December 31, 2022. The cash payments related to the credit were received in January 2023, and accordingly the credit was reflected in other current assets on the consolidated balance sheet for the year ended December 31, 2022.
Research and Development Tax Incentive	Research and Development Tax Incentive The Company is eligible under the AusIndustry Research and Tax Development Tax Incentive Program to obtain a cash amount from the Australian Taxation Office (“ATO”). The tax incentive is available to the Company on the basis of specific criteria with which the Company must comply related to research and development expenditures in Australia. The Company accounts for the grant under ASU No. 2021-10. The Company recognizes the Research and Development Tax Incentive (grant) as it incurs costs eligible for reimbursement under the AusIndustry Research and Tax Development Tax Incentive Program when it is reasonably assured that the grant funding will be received, as evidenced through enrollment in the program and when the applicable conditions under the program have been met. During the years ended December 31, 2022 and 2021 , respectively, the Company recorded $ 0.2 million and $ 0.6 million, respectively, of research and development tax incentives as contra-research and development expense over the periods in which the Company recognized the eligible research and development activities taking place in Australia.
Net Income (Loss) per Share	Net Income (Loss) per Share The Company follows the two-class method when computing net income (loss) per share attributable to common stockholders as the Company has issued shares that meet the definition of participating securities. Net income (loss) allocable to participating securities is calculated as net income (loss) less cumulative dividends on preferred stock accrued during the period, whether or not declared, and increases or decreases in the carrying value of preferred securities, including gains or losses on extinguishment. In determining net income (loss) attributable to common stockholders, the two-class method requires income (loss) allocable to participating securities for the period to be allocated between common and participating securities based upon their respective rights to share in the earnings as if all income (loss) allocable for the period had been distributed. The Company’s convertible preferred stock participates in any dividends declared by the Company and are therefore considered to be participating securities. During periods of loss, there is no allocation required under the two-class method since the participating securities do not have a contractual obligation to fund the losses of the Company. Basic net income (loss) per share attributable to common stockholders is computed by dividing the net income (loss) attributable to common stockholders by the weighted average number of shares of common stock outstanding for the period. Diluted net income (loss) per share attributable to common stockholders is computed by dividing the net income (loss) attributable to common stockholders by the weighted average number of shares of common stock outstanding for the period, including the effect of potentially dilutive common stock.
Emerging Growth Company Status	Emerging Growth Company Status The Company is an emerging growth company (“EGC”), as defined in the Jumpstart Our Business Startups Act (“JOBS Act”) and may take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not EGCs. The Company may take advantage of these exemptions until it is no longer an EGC under Section 107 of the JOBS Act, which provides that an EGC can take advantage of the extended transition period afforded by the JOBS Act for the implementation of new or revised accounting standards. The Company has elected to use the extended transition period for complying with new or revised accounting standards, and as a result of this election, the consolidated financial statements may not be comparable to companies that comply with public company FASB standards’ effective dates. The Company may take advantage of these exemptions up until December 31, 2026 or such earlier time that it is no longer an EGC.
Recently Adopted and Issued Accounting Pronouncement	Recently Adopted Accounting Pronouncements In February 2016, the FASB issued ASC 842, which replaces the existing guidance for leases. ASC 842 requires the identification of arrangements that should be accounted for as leases by lessees. In general, for lease arrangements exceeding a twelve-month term, these arrangements must now be recognized as assets and liabilities on the balance sheet of the lessee. Under ASC 842, a right-of-use asset and lease obligation will be recorded for all leases, whether operating or financing, while the income statement will reflect lease expense for operating leases and amortization/interest expense for financing leases. The balance sheet amount recorded for existing leases at the date of adoption of ASC 842 must be calculated using the applicable incremental borrowing rate at the date of adoption. The Company adopted ASC 842 using the modified retrospective approach effective January 1, 2022. The Company elected the package of practical expedients which allows entities to not reassess (i) whether an arrangement is or contains a lease, (ii) the classification of its leases, and (iii) the accounting for initial direct costs. Further, the Company elected, by class of underlying asset, the short-term lease exception for leases with terms of twelve months or less. In doing so, the Company did not recognize a lease liability or right-of-use asset on its balance sheets for such short-term leases. Finally, the Company elected, by class of underlying asset, the practical expedient to not separate lease and non-lease components. The impact of adoption is summarized in the table below (in thousands): As Reported Impact of As Adopted Operating lease right-of-use assets — 11,485 11,485 Finance lease right-of-use assets — 235 235 Property and equipment, net 5,611 ( 235 ) 5,376 Accrued expenses and other current liabilities 7,712 ( 213 ) 7,499 Deferred rent and lease incentive obligation, current 696 ( 696 ) — Operating lease liabilities, current — 3,484 3,484 Finance lease liabilities, current — 213 213 Deferred rent and lease incentive obligation, long-term 4,208 ( 4,208 ) — Operating lease liabilities, long-term — 12,905 12,905 Finance lease liabilities, long-term — 19 19 Other long-term liabilities 1,611 ( 19 ) 1,592 In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU 2019-12”), which is intended to simplify the accounting for income taxes. ASU 2019-12 removes certain exceptions related to the approach for intra-period tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. ASU 2019-12 also clarifies and simplifies other aspects of accounting for income taxes. The Company adopted ASU 2019-12 on January 1, 2022 . The adoption did no t have a material effect on the Company’s consolidated financial statements and related disclosures. In May 2021, the FASB issued ASU No. 2021-04, Earnings Per Share (Topic 260), Debt — Modifications and Extinguishments (Subtopic 470-50), Compensation — Stock Compensation (Topic 718), and Derivatives and Hedging — Contracts in Entity’s Own Equity (Subtopic 815-40) (“ASU 2021-04”). ASU 2021-04 clarifies and reduces diversity in an issuer’s accounting for modifications or exchanges of freestanding equity-classified written call options, including warrants, that remain equity-classified after modification or exchange. ASU 2021-04 requires an entity to treat a modification or an exchange of a freestanding equity-classified written call option that remains equity-classified after the modification or exchange as an exchange of the original instrument for a new instrument and provides guidance on measuring and recognizing the effect of a modification or an exchange. The Company adopted ASU 2021-04 on January 1, 2022 . The adoption did no t have a material impact on the Company’s consolidated financial statements and related disclosures. In November 2021, the FASB issued ASU No. 2021-10. ASU 2021-10 increases the transparency of transactions with the government that are accounted for by applying a grant or contribution accounting model, and it aims to reduce diversity that currently exists in the recognition, measurement, presentation, and disclosure of government assistance received by business entities due to the lack of specific authoritative guidance in GAAP. ASU 2021-10 requires an entity to provide information regarding the nature of the transaction with a government and the related accounting policy used to account for this transaction, the line item on the consolidated balance sheet and consolidated statement of operations and comprehensive loss that are affected by the transaction and the amounts applicable to each financial statement line item, and the significant terms and conditions of the transaction, including commitments and contingencies. The Company adopted ASU 2021-10 on January 1, 2022 using the prospective approach. The adoption did no t have a material effect on the Company’s consolidated financial statements and related disclosures. Recently Issued Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326)—Measurement of Credit Losses on Financial Instruments, which has been subsequently amended by ASU No. 2018-19, ASU No. 2019-04, ASU No. 2019-05, ASU No. 2019-10, ASU No. 2019-11 and ASU No. 2020-03 (“ASU 2016-13”). The provisions of ASU 2016-13 modify the impairment model to utilize an expected loss methodology in place of the currently used incurred loss methodology and require a consideration of a broader range of reasonable and supportable information to inform credit loss estimates. ASU 2016-13 is effective for the Company on January 1, 2023. The Company does not expect the adoption to have a material effect on the Company's consolidated financial statements and related disclosures. In August 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging Contracts in Entity’s Own Equity (Subtopic 815-40) (“ASU 2020-06”), which reduces the number of accounting models for convertible debt instruments and convertible preferred stock as well as amends the derivatives scope exception for contracts in an entity’s own equity. ASU 2020-06 is effective for the Company on January 1, 2024, with early adoption permitted. The Company is currently evaluating the potential impact that this standard may have on its consolidated financial statements and related disclosures.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Schedule of Cash, Cash Equivalents and Restricted Cash	Cash, cash equivalents and restricted cash consisted of the following (in thousands): December 31, 2022 2021 Cash and cash equivalents $ 34,607 $ 36,455 Restricted cash, current 38 — Restricted cash, long-term 924 1,128 Total cash, cash equivalents and restricted cash as shown on the statement $ 35,569 $ 37,583
Schedule of Property and Equipment Estimated Useful Lives	Property and equipment is stated at cost, net of accumulated depreciation and amortization. Depreciation and amortization are calculated using the straight-line method over the estimated useful lives of the assets, which are as follows: Estimated Useful Life Computer equipment and software 3 years Furniture and fixtures 7 years Laboratory equipment 5 years Leasehold improvements Shorter of useful life or remaining lease term
Summary of Impact of Adoption	As Reported Impact of As Adopted Operating lease right-of-use assets — 11,485 11,485 Finance lease right-of-use assets — 235 235 Property and equipment, net 5,611 ( 235 ) 5,376 Accrued expenses and other current liabilities 7,712 ( 213 ) 7,499 Deferred rent and lease incentive obligation, current 696 ( 696 ) — Operating lease liabilities, current — 3,484 3,484 Finance lease liabilities, current — 213 213 Deferred rent and lease incentive obligation, long-term 4,208 ( 4,208 ) — Operating lease liabilities, long-term — 12,905 12,905 Finance lease liabilities, long-term — 19 19 Other long-term liabilities 1,611 ( 19 ) 1,592

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Schedule of Financial Assets Measured at Fair Value on Recurring Basis	The Company measures the following financial assets at fair value on a recurring basis. The fair value of these assets was determined as follows (in thousands): Balance at December 31, 2022 Quoted Prices Significant Significant Cash equivalents: Money market mutual funds $ 34,059 $ 34,059 $ — $ — Total cash equivalents $ 34,059 $ 34,059 $ — $ — Available-for-sale securities: U.S. Treasury securities $ 36,246 $ — $ 36,246 $ — U.S. Agency bonds 22,523 — 22,523 — U.S. Agency discount notes 11,185 — 11,185 — Total available-for-sale securities $ 69,954 $ — $ 69,954 $ — Balance at Quoted Prices Significant Significant Cash equivalents: Money market mutual funds $ 31,726 $ 31,726 $ — $ — Total cash equivalents $ 31,726 $ 31,726 $ — $ — Available-for-sale securities: U.S. Treasury securities $ 61,373 $ — $ 61,373 $ — Corporate debt securities 33,806 — 33,806 — U.S. Agency bonds 15,114 — 15,114 — Commercial paper 1,999 — 1,999 — Total available-for-sale securities $ 112,292 $ — $ 112,292 $ — Available-for-sale securities, long-term: U.S. Treasury securities $ 13,547 $ — $ 13,547 $ — Total available-for-sale securities, long-term $ 13,547 $ — $ 13,547 $ —

Available-for-sale Securities (

Available-for-sale Securities (Tables)	12 Months Ended
	Dec. 31, 2022
Investments, Debt and Equity Securities [Abstract]
Summary of Available-for-Sale Securities	The following table summarizes the Company’s available-for-sale securities (in thousands): December 31, 2022 Amortized Gross Gross Fair Value Available-for-sale securities: U.S. Treasury securities $ 36,452 $ — $ ( 206 ) $ 36,246 U.S. Agency bonds 22,550 8 ( 35 ) 22,523 U.S. Agency discount notes 11,175 10 — 11,185 Total available-for-sale securities $ 70,177 $ 18 $ ( 241 ) $ 69,954 December 31, 2021 Amortized Gross Gross Fair Value Available-for-sale securities: U.S. Treasury securities $ 61,450 $ — $ ( 77 ) $ 61,373 Corporate debt securities 33,814 — ( 8 ) 33,806 U.S. Agency bonds 15,123 — ( 9 ) 15,114 Commercial paper 1,999 — — 1,999 Total available-for-sale securities $ 112,386 $ — $ ( 94 ) $ 112,292 Available-for-sale securities, long-term: U.S. Treasury securities $ 13,585 $ — $ ( 38 ) $ 13,547 Total available-for-sale securities, long-term $ 13,585 $ — $ ( 38 ) $ 13,547

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment, Net	Property and equipment, net consisted of the following (in thousands): December 31, 2022 2021 Leasehold improvements $ 7,096 $ 7,096 Laboratory equipment 3,406 3,339 Computer equipment and software 212 212 Furniture and fixtures 947 947 Construction in progress 40 — Total property and equipment 11,701 11,594 Accumulated depreciation ( 7,175 ) ( 5,983 ) Property and equipment, net $ 4,526 $ 5,611

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	12 Months Ended
	Dec. 31, 2022
Payables and Accruals [Abstract]
Components of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consisted of the following (in thousands): Years Ended December 31, 2022 2021 Accrued research and development expenses $ 3,469 $ 3,152 Accrued compensation and related expenses 2,883 2,932 Accrued professional fees 1,170 380 Other accrued expenses 887 1,035 Equipment financing, current — 213 $ 8,409 $ 7,712

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2022
Leases [Abstract]
Components of Lease Cost	The components of lease cost for the year ended December 31, 2022 were as follows (in thousands): Operating lease cost $ 2,917 Variable lease cost 782 Short-term lease cost 17 Finance lease cost: Amortization of right-of-use assets 201 Interest expense on lease liabilities 14 Sublease income ( 2,476 ) Total lease cost $ 1,455
Schedule of Supplemental Cash Flow Information Related to Leases	Supplemental cash flow information related to the Company's leases for the year ended December 31, 2022 were as follow (in thousands): Cash paid for amounts included in the measurement of lease liabilities Operating cash flows for operating leases $ 3,616 Operating cash flows for finance leases $ 14 Financing cash flows for finance leases $ 213
Schedule of Future Minimum Lease Payments Under Noncancelable Leases	Future minimum lease payments under the Company’s noncancelable leases as of December 31, 2022 were as follows (in thousands): Operating Leases Finance Leases 2023 $ 3,705 $ 19 2024 3,796 — 2025 3,889 — 2026 3,984 — 2027 1,350 — Total lease payments 16,724 19 Present value adjustment ( 2,690 ) — Present value of lease payments $ 14,034 $ 19

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2022
Equity [Abstract]
Summary of Common Stock Reserved for Future Issuance	The Company had the following shares of common stock reserved for future issuance: December 31, 2022 2021 Shares reserved for exercise of outstanding stock options under the 2015 Stock 2,155,577 2,540,963 Shares reserved for exercise of outstanding stock options under the 2021 Stock 1,320,800 496,500 Shares reserved for vesting of restricted stock units granted under the 2021 Stock 219,742 — Shares reserved for future awards under the 2021 Stock Incentive Plan 1,561,034 1,221,593 Shares reserved for issuance under the 2021 Employee Stock Purchase Plan 815,556 566,037 Total shares of common stock reserved 6,072,709 4,825,093

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2022
Share-Based Payment Arrangement [Abstract]
Summary of Restricted Stock Activity	A summary of the Company’s restricted stock activity and related information is as follows: Number of Weighted Unvested as of December 31, 2021 12,537 $ 24.79 Vested ( 12,519 ) 24.80 Canceled/Forfeited ( 18 ) 15.37 Unvested as of December 31, 2022 — $ —
Summary of Restricted Stock Unit Activity	A summary of the Company’s restricted stock unit activity and related information is as follows: Number of Weighted Unvested as of December 31, 2021 — $ — Granted 313,185 3.50 Vested — — Canceled/Forfeited ( 93,443 ) 3.50 Unvested as of December 31, 2022 219,742 $ 3.50
Summary of Stock Option Activity	A summary of the Company’s stock option activity and related information is as follows: Number of Weighted Weighted Aggregate (In years) (In thousands) Outstanding as of December 31, 2021 3,037,463 $ 5.34 8.9 $ 629 Granted 1,075,200 Exercised — Cancelled/forfeited ( 636,286 ) Outstanding as of December 31, 2022 3,476,377 $ 4.76 7.4 $ 255 Exercisable as of December 31, 2022 1,671,073 $ 5.13 6.6 $ — Vested and expected to vest as of December 31, 2022 3,476,377 $ 4.76 7.4 $ 255
Summary of Estimated Fair Value of Stock Options using Black-Scholes Valuation Model with the Assumptions	The Company estimated the fair value of stock options at the date of grant using the Black-Scholes valuation model with the following assumptions: Year Ended December 31, 2022 2021 Risk-free interest rate 1.63 - 4.26 % 0.82 - 1.34 % Expected annual dividend yield 0.00 % 0.00 % Expected stock price volatility 86.7 - 94.1 % 85.4 - 89.3 % Expected term (in years) 5.5 - 6.1 5.0 - 6.1
Schedule of Components and Classification of Stock-Based Compensation Expense	The following table presents the components and classification of stock-based compensation expense (in thousands): Year Ended December 31, 2022 2021 Research and development $ 1,433 $ 1,237 General and administrative 1,767 1,580 Total stock-based compensation expense $ 3,200 $ 2,817

Net Loss per Share (Tables)

Net Loss per Share (Tables)	12 Months Ended
	Dec. 31, 2022
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders	Basic and diluted net loss per share attributable to common stockholders was calculated as follows (in thousands, except share and per share amounts) : Year Ended December 31, 2022 2021 Numerator: Net loss $ ( 63,005 ) $ ( 51,823 ) Cumulative dividends on convertible preferred stock — ( 2,309 ) Net loss attributable to common stockholders $ ( 63,005 ) $ ( 54,132 ) Denominator: Weighted-average shares of common stock outstanding, basic and diluted 24,960,008 21,733,960 Net loss per share attributable to common stockholders, basic and diluted $ ( 2.52 ) $ ( 2.49 )
Schedule of Anti-Dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share	The following table sets forth the outstanding shares of common stock equivalents, presented based on amounts outstanding at each period end, that were excluded from the calculation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have been anti-dilutive: Year Ended December 31, 2022 2021 Outstanding stock options 3,476,377 3,037,463 Unvested restricted stock units 219,742 — Unvested restricted stock awards — 12,537 Total 3,696,119 3,050,000

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Schedule of Loss before Provision for Income Tax	For financial reporting purposes, loss before provision for income taxes, includes the following components (in thousands): Year Ended December 31, 2022 2021 Domestic $ ( 62,859 ) $ ( 50,825 ) Foreign 94 799 Loss before income taxes $ ( 62,765 ) $ ( 50,026 )
Components of Provision (Benefit) for Income Taxes	The provision (benefit) for income taxes consists of the following (in thousands): Year Ended December 31, 2022 2021 Current: Federal $ — $ — State 13 — Foreign 227 1,797 Total Current 240 1,797 Deferred: Federal — — State — — Foreign — — Total Deferred — — Loss before income taxes $ 240 $ 1,797
Summary of Reconciliation of Expected Income Tax (Benefit) Computed Using Federal Statutory Income Tax Rate to Effective Income Tax Rate	A reconciliation of the expected income tax (benefit) computed using the federal statutory income tax rate to the Company’s effective income tax rate is as follows: Year Ended December 31, 2022 2021 Expected income tax benefit at the federal statutory rate 21.0 % 21.0 % State taxes, net 5.9 5.8 Foreign taxes — ( 0.5 ) Change in valuation allowance ( 28.6 ) ( 27.2 ) Research and development tax credits 3.2 0.7 Rate differential on foreign operations — ( 0.1 ) Stock compensation ( 0.9 ) ( 0.5 ) Uncertain Tax Position — ( 2.9 ) Permanent differences ( 0.5 ) 0.1 Other ( 0.5 ) — Effective income tax rate ( 0.4 )% ( 3.6 )%
Schedule of Significant Components of Deferred Tax Assets and Liabilities	The significant components of the Company’s deferred tax assets and liabilities consisted of the following (in thousands): December 31, 2022 2021 Deferred tax assets: Federal, state and foreign net operating loss carryforwards $ 59,068 $ 53,075 Research and development and other credits 3,835 1,840 Lease liability 3,800 — Capitalized research and development expenses 9,998 — Deferred rent and lease incentive obligation — 1,321 Accrued expenses and other 1,428 1,551 Total gross deferred tax assets 78,129 57,787 Valuation allowance ( 74,926 ) ( 57,013 ) Total deferred tax assets $ 3,203 $ 774 Deferred tax liabilities: Right of use assets ( 2,679 ) — Depreciation of fixed assets ( 524 ) ( 774 ) Total deferred tax liabilities $ ( 3,203 ) $ ( 774 ) Net deferred taxes $ — $ —
Schedule of Changes in Valuation Allowance for Deferred Tax Assets	Changes in the valuation allowance for deferred tax assets were as follows (in thousands): Year Ended December 31, 2022 2021 Valuation allowance at beginning of the year $ 57,013 $ 44,305 Increases recorded to income tax provision 17,913 12,708 Valuation allowance at end of year $ 74,926 $ 57,013
Summary of Reconciliation of Gross Unrecognized Tax Benefits	A reconciliation of the gross unrecognized tax benefits are as follows (in thousands): Year Ended December 31, 2022 2021 Unrecognized tax benefits at the beginning of the period $ 2,084 $ — Increases for current tax positions — 2,084 Reductions related to previous tax positions ( 85 ) — Reductions related to translation adjustments ( 369 ) — Unrecognized tax benefits at the end of the period $ 1,630 $ 2,084

Nature of the Business - Additi

Nature of the Business - Additional Information (Details) $ / shares in Units, $ in Thousands				12 Months Ended
	Feb. 24, 2021 USD ($) shares	Feb. 17, 2021 $ / shares shares	Feb. 05, 2021	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($) shares
Nature Of Business Disclosure [Line Items]
Aggregate proceeds from initial public offering | $	$ 125,000
Cash, cash equivalents and available-for-sale securities | $				$ 104,600
Accumulated deficit | $				$ 277,517	$ 214,512
Initial Public Offering
Nature Of Business Disclosure [Line Items]
Number of shares issued and sold | shares		7,062,000
Stock issued, price per share | $ / shares		$ 18
Underwriters
Nature Of Business Disclosure [Line Items]
Number of shares issued and sold | shares	600,000
Common Stock
Nature Of Business Disclosure [Line Items]
Reverse stock-split, description				on February 5, 2021, the Company’s board of directors approved a 1-for-5.3 reverse stock split of the Company’s common stock.
Reverse stock-split ratio			0.1886
Number of shares issued and sold | shares					7,662,000

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Schedule of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Cash and cash equivalents	$ 34,607	$ 36,455
Restricted cash, current	38
Restricted cash, long-term	924	1,128
Total cash, cash equivalents and restricted cash as shown on the statement of cash flows	$ 35,569	$ 37,583	$ 29,218

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Summary of Significant Accounting Policies [Line Items]
Off-balance sheet arrangements	$ 0	$ 0
Allowance of accounts receivable	0	0
Unrealized loss on available-for-sale securities	(91,000)	(131,000)
Research and development tax incentives	$ 200,000	$ 600,000
ASU 2016-02
Summary of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted [true false]	true
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2022
ASU 2019-12
Summary of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted [true false]	true
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2022
Change in accounting principle, accounting standards update, immaterial effect [true false]	true
ASU 2021-10
Summary of Significant Accounting Policies [Line Items]
Employee retention credit	$ 900,000
Change in accounting principle, accounting standards update, adopted [true false]	true
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2022
Change in accounting principle, accounting standards update, immaterial effect [true false]	true
ASU 2021-04
Summary of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted [true false]	true
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2022
Change in accounting principle, accounting standards update, immaterial effect [true false]	true
Maximum
Summary of Significant Accounting Policies [Line Items]
FDIC insured amount	$ 250,000

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Schedule of Property and Equipment Estimated Useful Lives (Details)	12 Months Ended
	Dec. 31, 2022
Computer equipment and software
Property, Plant and Equipment [Line Items]
Useful lives of property and equipment	3 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Useful lives of property and equipment	7 years
Laboratory equipment
Property, Plant and Equipment [Line Items]
Useful lives of property and equipment	5 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Useful lives of property and equipment	Shorter of useful life or remaining lease term

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Summary of Impact of Adoption (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Jan. 01, 2022	Dec. 31, 2021
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets	$ 9,859	$ 11,485
Finance lease right-of-use assets	34	235
Property and equipment, net	4,526	5,376	$ 5,611
Accrued expenses and other current liabilities		7,499	7,712
Deferred rent and lease incentive obligation, current			696
Operating lease liabilities, current	3,567	3,484
Finance lease liabilities, current	19	213
Deferred rent and lease incentive obligation, long-term			4,208
Operating lease liabilities, long-term	$ 10,467	12,905
Finance lease liabilities, long-term		$ 19
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Liabilities
Other long-term liabilities		$ 1,592	$ 1,611
Impact of Adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets		11,485
Finance lease right-of-use assets		235
Property and equipment, net		(235)
Accrued expenses and other current liabilities		(213)
Deferred rent and lease incentive obligation, current		(696)
Operating lease liabilities, current		3,484
Finance lease liabilities, current		213
Deferred rent and lease incentive obligation, long-term		(4,208)
Operating lease liabilities, long-term		12,905
Finance lease liabilities, long-term		19
Other long-term liabilities		$ (19)

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Financial Assets Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Available-for-sale securities	$ 69,954	$ 112,292
Available-for-sale securities, long-term		13,547
Fair Value, Measurements
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Total cash equivalents	34,059	31,726
Available-for-sale securities	69,954	112,292
Available-for-sale securities, long-term		13,547
Fair Value, Measurements | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Total cash equivalents	34,059	31,726
Fair Value, Measurements | Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Available-for-sale securities	69,954	112,292
Available-for-sale securities, long-term		13,547
Money Market Funds | Fair Value, Measurements
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Total cash equivalents	34,059	31,726
Money Market Funds | Fair Value, Measurements | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Total cash equivalents	34,059	31,726
U.S. Agency discount notes | Fair Value, Measurements
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Available-for-sale securities	11,185
U.S. Agency discount notes | Fair Value, Measurements | Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Available-for-sale securities	11,185
U.S. Treasury securities | Fair Value, Measurements
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Available-for-sale securities	36,246	61,373
Available-for-sale securities, long-term		13,547
U.S. Treasury securities | Fair Value, Measurements | Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Available-for-sale securities	36,246	61,373
Available-for-sale securities, long-term		13,547
Corporate debt securities | Fair Value, Measurements
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Available-for-sale securities		33,806
Corporate debt securities | Fair Value, Measurements | Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Available-for-sale securities		33,806
U.S. Agency bonds | Fair Value, Measurements
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Available-for-sale securities	22,523	15,114
U.S. Agency bonds | Fair Value, Measurements | Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Available-for-sale securities	$ 22,523	15,114
Commercial paper | Fair Value, Measurements
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Available-for-sale securities		1,999
Commercial paper | Fair Value, Measurements | Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Available-for-sale securities		$ 1,999

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value, assets, level 1 to level 2 transfers, amount	$ 0	$ 0
Fair value, assets, level 2 to level 1 transfers, amount	0	0
Fair value, assets transfers into level 3, amount	0	0
Fair value, assets transfers out of level 3, amount	0	0
Fair Value, Measurements
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Liabilities measured at fair value	$ 0	$ 0

Available-for-Sale Securities -

Available-for-Sale Securities - Summary of Available-for-Sale Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current
Available-for-sale Securities [Line Items]
Amortized Cost	$ 70,177	$ 112,386
Gross Unrealized Gains	18
Gross Unrealized Losses	(241)	(94)
Fair Value	69,954	112,292
Noncurrent
Available-for-sale Securities [Line Items]
Amortized Cost		13,585
Gross Unrealized Losses		(38)
Fair Value		13,547
U.S. Treasury securities | Current
Available-for-sale Securities [Line Items]
Amortized Cost	36,452	61,450
Gross Unrealized Losses	(206)	(77)
Fair Value	36,246	61,373
U.S. Treasury securities | Noncurrent
Available-for-sale Securities [Line Items]
Amortized Cost		13,585
Gross Unrealized Losses		(38)
Fair Value		13,547
Corporate debt securities | Current
Available-for-sale Securities [Line Items]
Amortized Cost		33,814
Gross Unrealized Losses		(8)
Fair Value		33,806
U.S. Agency bonds | Current
Available-for-sale Securities [Line Items]
Amortized Cost	22,550	15,123
Gross Unrealized Gains	8
Gross Unrealized Losses	(35)	(9)
Fair Value	22,523	15,114
U.S. Agency discount notes | Current
Available-for-sale Securities [Line Items]
Amortized Cost	11,175
Gross Unrealized Gains	10
Fair Value	$ 11,185
Commercial paper | Current
Available-for-sale Securities [Line Items]
Amortized Cost		1,999
Fair Value		$ 1,999

Available-for-Sale Securities_2

Available-for-Sale Securities - Additional Information (Details)	12 Months Ended
	Dec. 31, 2022 USD ($) Investment	Dec. 31, 2021 USD ($) Investment
Investments, Debt and Equity Securities [Abstract]
Number of investments in available-for-sale securities in unrealized loss position | Investment	25	43
Available-for-sale securities, unrealized loss position	$ 48,100,000	$ 120,300,000
Other-than-temporary impairments related to available-for-sale securities in an unrealized loss position	$ 0	$ 0
Investments matured	1 year	5 years
Available-for-sale securities, realized gains loss	$ 0	$ 0

Property and Equipment, Net - S

Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Jan. 01, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 11,701		$ 11,594
Accumulated depreciation	(7,175)		(5,983)
Property and equipment, net	4,526	$ 5,376	5,611
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	7,096		7,096
Laboratory equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	3,406		3,339
Computer equipment and software
Property, Plant and Equipment [Line Items]
Total property and equipment	212		212
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment	947		$ 947
Construction in Progress
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 40

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jul. 31, 2020	Dec. 31, 2022	Dec. 31, 2021	Jan. 01, 2022
Property, Plant and Equipment [Line Items]
Present value of lease payments		$ 19
Remaining portion of capital lease liability		19		$ 213
Depreciation expense		1,500	$ 1,400
Right-of-use asset, finance		$ 34		$ 235
Laboratory equipment
Property, Plant and Equipment [Line Items]
One-time cash payment	$ 500
Payments to acquire equipment on lease	$ 200
Lease term	2 years 6 months

Accrued Expenses Other Current

Accrued Expenses Other Current Liabilities - Components of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Payables and Accruals [Abstract]
Accrued research and development expenses	$ 3,469	$ 3,152
Accrued compensation and related expenses	2,883	2,932
Accrued professional fees	1,170	380
Other accrued expenses	887	1,035
Equipment financing, current		213
Accrued Expenses and Other Current Liabilities	$ 8,409	$ 7,712

Leases - Additional Information

Leases - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended						12 Months Ended
	Jan. 31, 2022	May 31, 2021	Jul. 31, 2020	Jan. 31, 2020	Sep. 30, 2019	Jul. 31, 2016	Dec. 31, 2022
Lessee, Lease, Description [Line Items]
Base rent payment						$ 2,100
Percentage of annual increase in operating lease						3%
Lease expiration date						2027-06
Operating lease, option to extend						true
Operating lease, renewal term						5 years
Lease secured by letter of credit						$ 500
Tenant improvement allowance by landlord						$ 5,300
Sublease Income							$ 2,476
Operating leases weighted-average remaining lease term							4 years 3 months 18 days
Operating lease weighted average incremental borrowing rate							8.70%
Finance lease weighted average remaining lease term							1 month 6 days
Finance lease weighted average incremental borrowing rate							10%
Variable lease cost							$ 782
Laboratory equipment
Lessee, Lease, Description [Line Items]
One-time cash payment			$ 500
Payments to acquire equipment on lease			$ 200
Lease term			2 years 6 months
Sublease Agreement | Office Space
Lessee, Lease, Description [Line Items]
Base rent payment	$ 300				$ 1,200
Lease expiration date					2027-01
Lease secured by letter of credit					$ 300
Lease term commencement month and year	2022-02
Lease term of contract	6 months
Sublease Income	$ 500
Lease term option to extend description	sublease granted the sublessee the right to extend for two terms of three months
Lease renewal term	3 months
Sublessee prepaid rent	$ 100
Sublease Agreement | Office and Laboratory Space
Lessee, Lease, Description [Line Items]
Base rent payment		$ 1,700
Lease term commencement month and year				2020-03
Lease term of contract				24 months
Sublease Income				$ 1,100
Lease term option to extend description				sublease provided the sublessee one option to extend for up to one year
Lease term option/right to extend				true
Lease renewal term				1 year
Percentage of sublease annual base rent increase				3%
Sublease extended date		Oct. 31, 2022
Security deposit				$ 200

Leases - Components of Lease Co

Leases - Components of Lease Cost (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($)
Leases [Abstract]
Operating lease cost	$ 2,917
Variable lease cost	782
Short-term lease cost	17
Finance lease cost:
Amortization of right-of-use assets	201
Interest expense on lease liabilities	14
Sublease income	(2,476)
Total lease cost	$ 1,455

Leases - Schedule of Supplement

Leases - Schedule of Supplemental Cash Flow Information Related to Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Operating cash flows for operating leases	$ 3,616
Operating cash flows for finance leases	14
Financing cash flows for finance leases	$ 213	$ 193

Leases - Schedule of Future Min

Leases - Schedule of Future Minimum Lease Payments Under Noncancelable Leases (Details) $ in Thousands	Dec. 31, 2022 USD ($)
Operating Leases
2023	$ 3,705
2024	3,796
2025	3,889
2026	3,984
2027	1,350
Total lease payments	16,724
Present value adjustment	(2,690)
Present value of lease payments	14,034
Finance Leases
2023	19
Total lease payments	19
Present value of lease payments	$ 19

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($)	1 Months Ended							12 Months Ended
	Jan. 31, 2022	May 31, 2021	Oct. 31, 2020	Jan. 31, 2020	Sep. 30, 2019	Aug. 31, 2019	Jul. 31, 2016	Dec. 31, 2022	Oct. 31, 2019
Other Commitments [Line Items]
Base rent payment							$ 2,100,000
Percentage of annual increase in operating lease							3%
Lease expiration date							2027-06
Operating lease, option to extend							true
Operating lease, renewal term							5 years
Lease secured by letter of credit							$ 500,000
Tenant improvement allowance by landlord							$ 5,300,000
Rent expenses								$ 2,917,000
UFRF License
Other Commitments [Line Items]
Upfront fee paid			$ 100,000
Upfront Fee Payable			100,000
Contingent milestone payments maximum amount upon the achievement of certain clinical and regulatory milestones			800,000
Contingent milestone payments maximum amount upon the achievement of certain commercial sales milestones			11,200,000
Clinical, regulatory or commercial milestones achieved			$ 0
UCSF License
Other Commitments [Line Items]
Contingent milestone payments maximum amount upon the achievement of certain regulatory milestones									$ 500,000
Contingent milestone payments maximum amount upon the achievement of certain commercial sales milestones									5,000,000
Clinical, regulatory or commercial milestones achieved									$ 0
The University of Missouri License
Other Commitments [Line Items]
Upfront fee paid						$ 100,000		$ 100,000
Contingent milestone payments maximum amount upon the achievement of certain regulatory milestones						800,000
Contingent milestone payments maximum amount upon the achievement of certain commercial sales milestones						$ 13,100,000
Sublease Agreement | Office Space
Other Commitments [Line Items]
Base rent payment	$ 300,000				$ 1,200,000
Lease expiration date					2027-01
Lease secured by letter of credit					$ 300,000
Sublease Agreement | Office and Laboratory Space
Other Commitments [Line Items]
Base rent payment		$ 1,700,000
Percentage of sublease annual base rent increase				3%
Security deposit				$ 200,000
Sublease extended date		Oct. 31, 2022

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Future Minimum Rental Payments (Details) $ in Thousands	Dec. 31, 2022 USD ($)
Lessee, Operating Lease, Liability, to be Paid [Abstract]
2023	$ 3,705
2024	3,796
2025	3,889
2026	3,984
2027	1,350
Total lease payments	$ 16,724

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) $ / shares in Units, $ in Thousands		1 Months Ended		12 Months Ended
	Jan. 01, 2023 USD ($) shares	Aug. 31, 2022 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2022 Vote $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 shares
Common stock, Shares authorized | shares				200,000,000	200,000,000
Common stock, Par value | $ / shares				$ 0.001	$ 0.001
Preferred stock, price per share | $ / shares				$ 0.001	$ 0.001
Preferred stock, Shares authorized | shares				5,000,000	5,000,000
Common shares, votes per share | Vote				1
Issuance of common stock upon closing of IPO | $					$ 124,779
Net proceeds from issuance of common stock after deducting commissions | $					128,240
Maximum | At-the-Market Offering
Issuance of common stock upon closing of IPO | $		$ 50,000
Common Stock
Issuance of common stock upon closing of IPO | $					$ 7
Shares outstanding | shares				24,964,502	24,951,983	521,052
Number of shares issued and sold | shares					7,662,000
Common Stock | At-the-Market Offering
Percentage of compensation on gross proceeds common stock sold				3%
Shares outstanding | shares				0
Common Stock | At-the-Market Offering | Subsequent Event
Number of shares issued and sold | shares	50,482
Net proceeds from issuance of common stock after deducting commissions | $	$ 200
Common Stock | Maximum
Issuance of common stock upon closing of IPO | $			$ 200,000

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Common Stock Reserved for Future Issuance (Details) - shares	Dec. 31, 2022	Dec. 31, 2021
Class Of Stock [Line Items]
Common stock reserved for future issuance	6,072,709	4,825,093
2015 Stock Incentive Plan
Class Of Stock [Line Items]
Shares reserved for exercise of outstanding stock options	2,155,577	2,540,963
2021 Stock Incentive Plan
Class Of Stock [Line Items]
Shares reserved for exercise of outstanding stock options	1,320,800	496,500
Shares reserved for vesting of restricted stock units granted	219,742
Common stock reserved for future issuance	1,561,034	1,221,593
2021 Employee Stock Purchase Plan
Class Of Stock [Line Items]
Common stock reserved for future issuance	815,556	566,037

Convertible Preferred Stock - A

Convertible Preferred Stock - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Temporary Equity [Line Items]
Convertible preferred stock, Shares authorized			155,398,078
Conversion of convertible preferred stock into common stock	16,662,011
Cumulative dividends on convertible preferred stock		$ 2,309
Dividends on common stock		$ 2,300
Dividends accrued	$ 0
Preferred Stock Issued	0
Preferred Stock Outstanding	0

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($)		12 Months Ended
	Jan. 01, 2022	Dec. 31, 2022	Dec. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense, income tax benefits		$ 0	$ 0
Restricted Stock Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares issued		0	0
Aggregate fair value of awards vested		$ 300,000	$ 600,000
Unrecognized compensation cost related to unvested stock		$ 0
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares reserved for outstanding awards granted		1,075,200
Unrecognized compensation cost related to unvested stock		$ 5,300,000
Weighted-average period of unvested stock		2 years 4 months 24 days
Weighted average grant-date fair value of share options granted		$ 2.49	$ 6.99
Stock options, exercised		0
Intrinsic value of options exercised			$ 200,000
RSUs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation cost related to unvested stock		$ 800,000
Award, description		Pursuant to the terms of the applicable award agreements, each RSU represents the right to receive one share of the Company’s common stock.
2015 Stock Incentive Plan | Initial Public Offering
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares reserved for outstanding awards granted		2,155,577
Number of shares remained available for issuance		0
2021 Stock Incentive Plan | Initial Public Offering
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock, authorized for issuance			1,718,093
Percentage of cumulative increase of number of common shares outstanding		4%
Increase in number of shares of common stock authorized for issuance	998,079
Number of shares reserved for outstanding awards granted		1,540,542
Number of shares remained available for issuance		1,561,034
2021 Employee Stock Purchase Plan | Initial Public Offering
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock, authorized for issuance			566,037
Increase in number of shares of common stock authorized for issuance	249,519
Number of shares remained available for issuance		815,556
Number of shares issued		0

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Restricted Stock Activity (Details) - Restricted Stock Awards	12 Months Ended
	Dec. 31, 2022 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Stock Outstanding, Beginning Balance | shares	12,537
Number of Stock, Vested | shares	(12,519)
Number of Stock, Canceled/Forfeited | shares	(18)
Weighted Average Grant Date Fair Value, Beginning Balance | $ / shares	$ 24.79
Weighted Average Grant Date Fair Value, Vested | $ / shares	24.80
Weighted Average Grant Date Fair Value, Canceled/Forfeited | $ / shares	$ 15.37

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Restricted Stock Unit Activity (Details) - Restricted Stock Units	12 Months Ended
	Dec. 31, 2022 $ / shares shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of Stock, Granted | shares	313,185
Number of Stock, Canceled/Forfeited | shares	(93,443)
Number of Stock Outstanding, Ending Balance | shares	219,742
Weighted Average Grant Date Fair Value, Granted | $ / shares	$ 3.50
Weighted Average Grant Date Fair Value, Canceled/Forfeited | $ / shares	3.50
Weighted Average Grant Date Fair Value, Ending Balance | $ / shares	$ 3.50

Stock-Based Compensation - Su_3

Stock-Based Compensation - Summary of Stock Option Activity (Details) - Stock Options - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Stock Options, Outstanding as of December 31, 2021	3,037,463
Number of Stock Options, Granted	1,075,200
Number of Stock Options, Exercised	0
Number of Stock Options, Cancelled/forfeited	(636,286)
Number of Stock Options, Outstanding as of December 31, 2022	3,476,377	3,037,463
Number of Stock Options, Exercisable as of December 31, 2022	1,671,073
Number of Stock Options, Vested and expected to vest as of December 31, 2022	3,476,377
Weighted Average Exercise Price, Outstanding as of December 31, 2021	$ 5.34
Weighted Average Exercise Price, Outstanding as of December 31, 2022	4.76	$ 5.34
Weighted Average Exercise Price, Exercisable as of December 31, 2022	5.13
Weighted Average Exercise Price, Vested and expected to vest as of December 31, 2022	$ 4.76
Weighted Average Remaining Contractual Term, Outstanding	7 years 4 months 24 days	8 years 10 months 24 days
Weighted Average Remaining Contractual Term, Exercisable as of December 31, 2022	6 years 7 months 6 days
Weighted Average Remaining Contractual Term, Vested and expected to vest as of December 31, 2022	7 years 4 months 24 days
Aggregate Intrinsic Value, Outstanding	$ 255	$ 629
Aggregate Intrinsic Value, Vested and expected to vest as of December 31, 2022	$ 255

Stock-Based Compensation - Su_4

Stock-Based Compensation - Summary of Estimated Fair Value of Stock Options using Black-Scholes Valuation Model with the Assumptions (Details) - Stock Options	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate, Minimum	1.63%	0.82%
Risk-free interest rate, Maximum	4.26%	1.34%
Expected annual dividend yield	0%	0%
Expected stock price volatility, Minimum	86.70%	85.40%
Expected stock price volatility, Maximum	94.10%	89.30%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	5 years 6 months	5 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	6 years 1 month 6 days	6 years 1 month 6 days

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Components and Classification of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 3,200	$ 2,817
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	1,433	1,237
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 1,767	$ 1,580

Net Loss per Share - Basic and

Net Loss per Share - Basic and Diluted Net Loss Per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Numerator:
Net loss	$ (63,005)	$ (51,823)
Cumulative dividends on convertible preferred stock		(2,309)
Net loss attributable to common stockholders	$ (63,005)	$ (54,132)
Denominator:
Weighted-average shares of common stock outstanding, basic	24,960,008	21,733,960
Weighted-average shares of common stock outstanding, diluted	24,960,008	21,733,960
Net loss per share attributable to common stockholders, basic	$ (2.52)	$ (2.49)
Net loss per share attributable to common stockholders, diluted	$ (2.52)	$ (2.49)

Net Loss per Share - Schedule o

Net Loss per Share - Schedule of Anti-Dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share, amount	3,696,119	3,050,000
Outstanding stock options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share, amount	3,476,377	3,037,463
Unvested restricted stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share, amount	219,742
Unvested restricted stock awards
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share, amount		12,537

License and Collaboration Agr_2

License and Collaboration Agreement with Regeneron - Additional Information (Details) - USD ($)	1 Months Ended		3 Months Ended	12 Months Ended
	Oct. 31, 2020	Nov. 30, 2017	Dec. 31, 2022	Dec. 31, 2022	Dec. 31, 2021
License And Collaboration Agreement With Regeneron [Line Items]
Research Term		5 years
Right to extend maximum research term		2 years
Upfront non-reimbursable fee		$ 25,000,000
Preferred stock, shares issued			0	0	0
Preferred stock, price per share			$ 0.001	$ 0.001	$ 0.001
Obliged to pay for each one year extension				$ 10,000,000
Eligible to receive for biologic research				35,500,000
Eligible to receive for research of small molecule				33,500,000
Upfront nonrefundable payment			$ 25,000,000	25,000,000
Ongoing research plan	$ 300,000			300,000
CDMO Initiation Fee	500,000
Milestone associated payment	500,000			5,500,000
Third party costs related to investigational new drug			10,000,000	10,000,000
Upfront payment				25,000,000
Milestone payment received				5,500,000
Extension fee			10,000,000	10,000,000
Transaction price under the collaboration				46,900,000
Remaining balance of reimbursable third party costs			1,400,000	1,400,000
Unbilled receivable related to extension fee					$ 10,000,000
Reduction in aggregate potential milestone payments	15,000,000
Transaction price				46,900,000
Received regeneron agreement amount				25,000,000
Preferred stock value issued
Contra-research and development expense				8,400,000	11,000,000
Deferred collaboration liability, current			9,383,000	9,383,000	8,118,000
Deferred collaboration liability, long term			6,765,000	6,765,000	16,431,000
Unbilled accounts receivable due from related party			0	0	$ 11,400,000
Obligated to pay				10,000,000
Maximum
License And Collaboration Agreement With Regeneron [Line Items]
Third party costs related to investigational new drug	$ 10,500,000		10,500,000	10,500,000
Minimum
License And Collaboration Agreement With Regeneron [Line Items]
Right to extend research term		1 year
Series C Preferred Stock
License And Collaboration Agreement With Regeneron [Line Items]
Preferred stock, shares issued	10,000,000
Preferred stock value issued			$ 4,400,000	$ 4,400,000
Series B Preferred Stock
License And Collaboration Agreement With Regeneron [Line Items]
Preferred stock, shares issued		12,500,000
Preferred stock, price per share		$ 2

Employee Retirement_Savings P_2

Employee Retirement/Savings Plan - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Maximum annual contribution per employee	4%	4%
Maximum contributions made by employer	$ 500,000	$ 300,000
Minimum
Defined Benefit Plan Disclosure [Line Items]
Percentage of employer matching contribution	50%	50%
Percentage of employer matching contribution gross pay	2%	2%
Maximum
Defined Benefit Plan Disclosure [Line Items]
Percentage of employer matching contribution	100%	100%
Percentage of employer matching contribution gross pay	3%	3%

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Operating Loss Carryforwards [Line Items]
Income tax expense (benefit)	$ 240,000	$ 1,797,000
Income tax benefit to U.S. operations due to uncertainty of future taxable income	$ 0	0
Tax Cuts and Jobs Act of 2017 research and development expenditures amortization period	5 years
Unrecognized tax benefits	$ 1,630,000	2,084,000
Unrecognized tax benefits that would affect income tax expense before consideration of valuation allowance	1,400,000
Unrecognized tax benefits deferred tax asset previously offset by a full valuation allowance	200,000
Accrued penalties and provisions for interest	500,000	400,000
Orphan Drug Tax Credit Carryforwards
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	$ 1,300,000
Tax credit carryforwards, expiration period	2043
Internal Revenue Service
Operating Loss Carryforwards [Line Items]
Annual limitation period subject to cumulative changes in ownership interest	3 years
Annual limitation subject to cumulative changes in ownership, percentage	50%
Australian Taxation Office
Operating Loss Carryforwards [Line Items]
Income tax return statute of limitation period	4 years
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 217,900,000	196,300,000
Net operating loss carryforwards with definite life	41,700,000
Net operating loss carryforwards with indefinite life	$ 176,200,000
Operating loss carryforwards, expiration period	2033
Federal | Research and Development Tax Credit Carryforwards
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	$ 1,900,000	$ 1,200,000
Tax credit carryforwards, expiration period	2033	2033
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 210,500,000	$ 187,900,000
Operating loss carryforwards, expiration period	2035	2035
State | Research and Development Tax Credit Carryforwards
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	$ 900,000	$ 800,000
Tax credit carryforwards, expiration period	2032	2032

Income Taxes - Schedule of Loss

Income Taxes - Schedule of Loss before Provision for Income Tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Domestic	$ (62,859)	$ (50,825)
Foreign	94	799
Net loss before provision for income taxes	$ (62,765)	$ (50,026)

Income Taxes - Components of Pr

Income Taxes - Components of Provision (Benefit) for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Current:
State	$ 13
Foreign	227	$ 1,797
Total Current	240	1,797
Loss before income taxes	$ 240	$ 1,797

Income Taxes - Summary of Recon

Income Taxes - Summary of Reconciliation of Expected Income Tax (Benefit) Computed Using Federal Statutory Income Tax Rate to Effective Income Tax Rate (Details)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Expected income tax benefit at the federal statutory rate	21%	21%
State taxes, net	5.90%	5.80%
Foreign taxes		(0.50%)
Change in valuation allowance	(28.60%)	(27.20%)
Research and development tax credits	3.20%	0.70%
Rate differential on foreign operations		(0.10%)
Stock compensation	(0.90%)	(0.50%)
Uncertain Tax Position		(2.90%)
Permanent differences	(0.50%)	0.10%
Other:	(0.50%)
Effective income tax rate	(0.40%)	(3.60%)

Income Taxes - Schedule of Sign

Income Taxes - Schedule of Significant Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Federal, state and foreign net operating loss carryforwards	$ 59,068	$ 53,075
Research and development and other credits	3,835	1,840
Lease liability	3,800
Capitalized research and development expenses	9,998
Deferred rent and lease incentive obligation		1,321
Accrued expenses and other	1,428	1,551
Total gross deferred tax assets	78,129	57,787
Valuation allowance	(74,926)	(57,013)	$ (44,305)
Total deferred tax assets	3,203	774
Deferred tax liabilities:
Right of use assets	(2,679)
Depreciation of fixed assets	(524)	(774)
Total deferred tax liabilities	$ (3,203)	$ (774)

Income Taxes - Schedule of Chan

Income Taxes - Schedule of Changes in Valuation Allowance for Deferred Tax Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Valuation allowance at beginning of the year	$ 57,013	$ 44,305
Increases recorded to income tax provision	17,913	12,708
Valuation allowance at end of year	$ 74,926	$ 57,013

Income Taxes - Summary of rec_2

Income Taxes - Summary of reconciliation of the gross unrecognized tax benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits, Beginning Balance	$ 2,084
Increases for current tax positions		$ 2,084
Reductions related to previous tax positions	(85)
Reductions related to translation adjustments	(369)
Unrecognized Tax Benefits, Ending Balance	$ 1,630	$ 2,084

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Related Party Transaction [Line Items]
Share of common stock held from Regeneron	24,964,502	24,951,983
Due to related party	$ 0	$ 200,000
Amount due to Regeneron	$ 0	$ 0
Shares held from Regeneron	0	0
Unbilled accounts receivable due from Regeneron	$ 0	$ 11,400,000
Consulting services expenses	0	200,000
Contra-research and development expense	$ 8,400,000	$ 11,000,000
Regeneron Agreement
Related Party Transaction [Line Items]
Share of common stock held from Regeneron	2,097,314
Percentage of common stock outstanding	8.40%

Subsequent Events Additional In

Subsequent Events Additional Information (Details) - USD ($) $ in Thousands		12 Months Ended
	Jan. 01, 2023	Dec. 31, 2021
Subsequent Event [Line Items]
Net proceeds from issuance of common stock after deducting commissions		$ 128,240
Common Stock
Subsequent Event [Line Items]
Number of shares issued and sold		7,662,000
Common Stock | At-the-Market Offering | Subsequent Event
Subsequent Event [Line Items]
Number of shares issued and sold	50,482
Net proceeds from issuance of common stock after deducting commissions	$ 200