Decibel Therapeutics (DBTX) 10-K 18 Mar 22 2021 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Mar. 09, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2021
Document Fiscal Year Focus	2021
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		24,956,347
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			$ 133.8
Documents Incorporated by Reference	The registrant intends to file a definitive proxy statement pursuant to Regulation 14A relating to the 2022 Annual Meeting of Stockholders within 120 days of the end of the registrant’s fiscal year ended December 31, 2021 . 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, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 36,455	$ 27,742
Available-for-sale securities	112,292	26,568
Accounts receivable from related party	11,402	1,237
Prepaid expenses and other current assets	4,042	2,281
Total current assets	164,191	57,828
Available-for-sale securities, long-term	13,547
Property and equipment, net	5,611	6,337
Other assets	1,128	3,120
Total assets	184,477	67,285
Current liabilities:
Accounts payable	4,012	2,131
Accrued expenses and other current liabilities	7,712	5,665
Deferred collaboration liability, current	8,118	10,968
Deferred rent and lease incentive obligation, current	696	610
Total current liabilities	20,538	19,374
Long-term liabilities:
Deferred collaboration liability, long term	16,431	4,177
Deferred rent and lease incentive obligation, long term	4,208	4,901
Other long-term liabilities	1,611	523
Total liabilities	42,788	28,975
Commitments and contingencies (Note 7)
Convertible preferred stock		93,091
Stockholders’ (deficit) equity:
Common stock, $0.001 par value; 200,000,000 shares authorized, 24,964,520 shares issued and 24,951,983 shares outstanding at December 31, 2021; 115,000,000 shares authorized, 573,793 shares issued and 521,052 shares outstanding at December 31, 2020	25	1
Additional paid-in capital	356,308	107,908
Accumulated other comprehensive loss	(132)	(1)
Accumulated deficit	(214,512)	(162,689)
Total stockholders’ equity (deficit)	141,689	(54,781)
Total liabilities, convertible preferred stock and stockholders’ equity (deficit)	$ 184,477	67,285
Series A convertible preferred stock
Long-term liabilities:
Convertible preferred stock		16,176
Series B convertible preferred stock
Long-term liabilities:
Convertible preferred stock		5,700
Series C convertible preferred stock
Long-term liabilities:
Convertible preferred stock		16,759
Series D convertible preferred stock
Long-term liabilities:
Convertible preferred stock		$ 54,456

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Convertible preferred stock, Shares authorized		155,398,078
Convertible preferred stock, Shares issued		139,527,869
Convertible preferred stock, Shares outstanding		139,527,869
Convertible preferred stock, Liquidation preference		$ 157,584
Preferred stock, Par value	$ 0.001	$ 0.001
Preferred stock, Shares authorized	5,000,000	0
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	115,000,000
Common stock, Shares issued	24,964,520	573,793
Common stock, Shares outstanding	24,951,983	521,052
Series A convertible preferred stock
Convertible preferred stock, Par value	$ 0.001	$ 0.001
Convertible preferred stock, Shares authorized	0	57,758,734
Convertible preferred stock, Shares issued	0	57,758,734
Convertible preferred stock, Shares outstanding	0	57,758,734
Convertible preferred stock, Liquidation preference		$ 40,284
Series B convertible preferred stock
Convertible preferred stock, Par value	$ 0.001	$ 0.001
Convertible preferred stock, Shares authorized	0	12,500,000
Convertible preferred stock, Shares issued	0	12,500,000
Convertible preferred stock, Shares outstanding	0	12,500,000
Convertible preferred stock, Liquidation preference		$ 16,334
Series C convertible preferred stock
Convertible preferred stock, Par value	$ 0.001	$ 0.001
Convertible preferred stock, Shares authorized	0	37,528,581
Convertible preferred stock, Shares issued	0	37,528,581
Convertible preferred stock, Shares outstanding	0	37,528,581
Convertible preferred stock, Liquidation preference		$ 45,457
Series D convertible preferred stock
Convertible preferred stock, Par value	$ 0.001	$ 0.001
Convertible preferred stock, Shares authorized	0	47,610,763
Convertible preferred stock, Shares issued	0	31,740,554
Convertible preferred stock, Shares outstanding	0	31,740,554
Convertible preferred stock, Liquidation preference		$ 55,509

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Operating expenses:
Research and development	$ 29,847	$ 25,322
General and administrative	20,384	14,241
Total operating expenses	50,231	39,563
Loss from operations	(50,231)	(39,563)
Other income:
Interest income	193	55
Other income, net	12	171
Total other income, net	205	226
Net loss before provision for income taxes	(50,026)	(39,337)
Provision for income taxes	(1,797)	0
Net loss	(51,823)	(39,337)
Cumulative dividends on convertible preferred stock	(2,309)	(12,176)
Gain on extinguishment of Series A, Series B and Series C convertible preferred stock	0	103,455
Undistributed earnings allocable to participating securities	0	(44,867)
Net income (loss) attributable to common stockholders, basic	(54,132)	7,075
Cumulative Dividends On Series B and Series C Convertible Preferred Stock	0	6,821
Gain on extinguishment of Series B and Series C convertible preferred stock	0	(61,949)
Undistributed earnings allocable to Series B and Series C participating securities	0	12,758
Net income (loss) attributable to common stockholders, diluted	$ (54,132)	$ (35,295)
Net income (loss) per share attributable to common stockholders
Basic	$ (2.49)	$ 14.84
Diluted	$ (2.49)	$ (19.65)
Weighted average shares of common stock outstanding
Basic	21,733,960	476,700
Diluted	21,733,960	1,795,860
Comprehensive loss:
Net loss	$ (51,823)	$ (39,337)
Other comprehensive income (loss):
Unrealized loss on available-for-sale securities, net of tax of $0	(131)	(11)
Total other comprehensive loss	(131)	(11)
Comprehensive loss	$ (51,954)	$ (39,348)

CONSOLIDATED STATEMENTS OF OP_2

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS)(Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
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) Income	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, 2019	$ (121,796)		$ 1,546	$ 10	$ (123,352)
Balance, Shares at Dec. 31, 2019						57,758,734	12,500,000	27,528,581
Balance at Dec. 31, 2019						$ 57,682	$ 24,957	$ 55,005
Balance, Shares at Dec. 31, 2019		434,942
Issuance of convertible preferred stock								$ 4,446
Issuance of convertible preferred stock, Shares								10,000,000
Extinguishment of Series A, Series B and Series C convertible preferred stock						$ (41,506)	$ (19,257)	$ (42,692)
Extinguishment of Series A, Series B and Series C convertible preferred stock, value	103,455		103,455
Issuance of Series D convertible preferred stock, net of issuance costs of $345									$ 54,456
Issuance of Series D convertible preferred stock, net of issuance costs of $345, Shares									31,740,554
Issuance of common stock upon exercise of stock options	70		70
Issuance of common stock upon exercise of stock options, Shares		15,849
Vesting of restricted common stock	24	$ 1	23
Vesting of restricted common stock, Shares		70,261
Stock-based compensation expense	2,814		2,814
Unrealized loss on available-for-sale securities	(11)			(11)
Net loss	(39,337)				(39,337)
Balance at Dec. 31, 2020	$ (54,781)	$ 1	107,908	(1)	(162,689)
Balance, Shares at Dec. 31, 2020	139,527,869					57,758,734	12,500,000	37,528,581	31,740,554
Balance at Dec. 31, 2020	$ 93,091					$ 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						0	0	0	0
Balance, Shares at Dec. 31, 2021		24,951,983

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' (DEFICIT) EQUITY (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Statement of Stockholders' Equity [Abstract]
Payments of Series D convertible preferred stock, issuance costs		$ 345
Issuance of common stock costs	$ 13,137

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Operating activities
Net loss	$ (51,823)	$ (39,337)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	2,817	2,814
Depreciation	1,413	1,642
(Gain) loss on disposal of property and equipment	(35)
Amortization (accretion) of available-for-sale securities	987	(33)
Changes in operating assets and liabilities:
Accounts receivable from related party	(10,165)	(1,237)
Prepaid expenses and other current assets	(1,761)	(1,024)
Accounts payable	1,881	1,123
Accrued expenses and other current liabilities	3,438	(278)
Deferred rent and lease incentive	(607)	(518)
Deferred collaboration liability	9,404	3,967
Other long-term liabilities	1,301	220
Net cash used in operating activities	(43,150)	(32,661)
Investing activities
Purchases of available-for-sale securities	(197,457)	(26,582)
Proceeds from maturities of available-for-sale securities	97,068	13,750
Proceeds from sale of property and equipment	139	92
Purchases of property and equipment	(745)	(273)
Net cash used in investing activities	(100,995)	(13,013)
Financing activities
Proceeds from the issuance of Series D convertible preferred stock	27,400	54,800
Payment of Series D convertible preferred stock issuance costs		(220)
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)	(206)
Proceeds from the exercise of stock options	319	70
Proceeds from equipment financing		499
Principal payments on equipment financing	(193)	(75)
Repurchases of early exercised restricted stock	(1)	(15)
Net cash provided by financing activities	152,510	54,853
Net increase in cash, cash equivalents and restricted cash	8,365	9,179
Cash, cash equivalents and restricted cash at beginning of period	29,218	20,039
Cash, cash equivalents and restricted cash at end of period	37,583	29,218
Supplemental cash flow information:
Cash paid for income taxes		7
Cash paid for interest	34	20
Supplemental disclosure of non-cash activities:
Gain on extinguishment of Series A, Series B and Series C convertible preferred stock		103,455
Issuance of Series C convertible preferred stock pursuant to Regeneron Amendment		4,446
Series D convertible preferred stock offering costs in accrued expenses		124
Initial public offering costs in accrued expenses		1,438
Property and equipment purchases in accrued expenses	46
Vesting of early exercised restricted stock	$ 18	$ 51

Nature of the Business

Nature of the Business	12 Months Ended
	Dec. 31, 2021
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. On October 30, 2020, the Company’s board of directors approved a 1-for- 10 reverse stock split of the Company’s common stock. 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 both reverse stock splits. 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. Liquidity Since its inception, the Company’s operations have been focused on organizing and staffing, business planning, raising capital, establishing the Company’s intellectual property portfolio and performing research and development of its product candidates, programs and platform. 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. As of December 31, 2021, the Company had cash, cash equivalents and available-for-sale securities of $ 162.3 million . The Company has determined that its existing capital resources will be sufficient to meet its projected operating expenses and capital expenditure requirements for at least twelve months from the date of issuance of these consolidated financial statements. The Company expects to experience negative cash flows from operations and net losses for the foreseeable future as it continues to invest significantly in research and development of its product candidates, preclinical and clinical development and platform. Management’s conclusion with respect to its ability to fund its operations is based on estimates that are subject to risks and uncertainties that may prove to be incorrect. If actual results differ from management’s estimates, the Company may be required to seek additional funding or curtail planned activities to reduce operating expenses, which may have an adverse impact on the Company’s ability to achieve its business objectives. Impact of the COVID-19 Pandemic 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. The Company is following, and plans to continue to follow, recommendations from federal, state and local governments regarding workplace policies, practices and procedures. In response to the COVID-19 pandemic and in accordance with direction from state and local governmental authorities, the Company previously restricted access to its facility to those individuals who must perform critical research, translational medicine and laboratory support activities that must be completed on site, limited the number of such people that can be present at its facility at any one time, and required that most of its employees work remotely. In February 2022 the Company re-opened its facility to all of its employees. Screening and enrollment in the Company's ongoing Phase 1b clinical trial of DB-020 in Australia and the United States have been adversely impacted by the COVID-19 pandemic. Patient screening and enrollment were paused in the second quarter of 2020 in both Australia and the United States, and screening for enrollment did not resume until early in the third quarter of 2020 in Australia and early in the fourth quarter of 2020 in the United States. The Company has also experienced delays in site start-up and the withdrawal of some sites in the United States. In addition, the Company and the third-party manufacturers, contract research organizations and academic collaborators that the Company engages have faced in the past and may face in the future disruptions that could affect its ability to initiate and complete preclinical studies or clinical trials, including disruptions in procuring items that are essential for research and development activities, such as, for example, raw materials used in the manufacture of its product candidates, laboratory supplies for preclinical studies and clinical trials, or animals that are used for preclinical testing, in each case, for which there may be shortages because of ongoing efforts to address the COVID-19 pandemic and supply chain disruptions. The Company cannot be certain what the overall impact of the COVID-19 pandemic will be on its business, and the pandemic has the potential to adversely affect the Company’s business, financial condition, results of operations and prospects.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2021
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, equity-based compensation, 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, and the accrual of research and development expenses. 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 is mainly comprised of corporate obligations and money market accounts invested in U.S. Treasury securities. 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 other assets on the consolidated balance sheets. Cash, cash equivalents and restricted cash consisted of the following (in thousands): December 31, 2021 2020 Cash and cash equivalents $ 36,455 $ 27,742 Restricted cash 1,128 1,476 Total cash, cash equivalents and restricted cash as shown on the statement $ 37,583 $ 29,218 Available-For-Sale Securities Available-for-sale securities primarily consist of corporate obligations, agency bonds and U.S. Treasury 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 income (loss), which is a separate component of stockholders’ (deficit) 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 income (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 investment-grade 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, 2021 and 2020, 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, 2021, and 2020 , 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, 2021 and 2020 . 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, 2021 and 2020 , 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. Deferred Offering Costs The Company capitalizes certain legal, professional, accounting and other third-party fees that are directly associated with in-process equity financings as deferred offering costs until the related financings are consummated. After consummation of the equity financing, such costs are reclassified as a reduction to additional paid-in capital generated as a result of the related financing. Should an in-process equity financing be abandoned, the deferred offering costs will be expensed immediately as a charge to operating expenses in the consolidated statements of operations and comprehensive income (loss). Deferred offering costs are presented as a component of other assets on the consolidated balance sheets. As of December 31, 2021, the Company had no deferred offering costs. As of December 31, 2020, the Company capitalized $ 1.6 million of deferred offering costs related to the IPO of its common stock. Deferred Rent The Company’s operating lease agreements include scheduled rent escalations over the lease term, as well as a tenant improvement allowance provided to the Company upon execution of the lease or as certain tenant improvement costs are incurred. Rent expense is recognized on a straight-line basis over the term of the lease. Tenant improvement allowances are amortized as earned on a straight-line basis over the term of the lease as a reduction to rent expense. Deferred rent consists of the difference between cash payments and the recognition of rent expense on a straight-line basis over the term of the lease and the unamortized portion of tenant improvement allowances, if applicable. Convertible Preferred Stock The Company records all convertible preferred stock upon issuance at its respective fair value or original issuance price less issuance costs, as stipulated by its terms. The Company classifies its convertible preferred stock outside of stockholders’ equity (deficit) as the redemption of such shares is outside the Company’s control. The Company does not adjust the carrying value of the convertible preferred stock to redemption value until the contingent events are considered probable of occurring. 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, facilities costs and laboratory supplies, depreciation, manufacturing expenses and external costs of outside vendors engaged to conduct preclinical and clinical development activities. 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 income (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 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 and founders, generally in the form of stock options and restricted stock. 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 primarily issues stock options and restricted stock with service-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. The Company has no awards with performance-based or 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 income (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 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 granted with service-based vesting conditions 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. Prior to the completion of its IPO, given the absence of an active market for our common stock, the fair values of the shares of common stock underlying its stock-based awards were determined on each grant date by the Company’s board of directors with input from management, considering its most recently available third-party valuations of its common stock and the board of director’s assessment of additional objective and subjective factors that it believed were relevant and which may have changed from the date of the most recent valuation through the grant date. Historically, these independent third-party valuations of its equity instruments were performed contemporaneously with identified value inflection points. The third-party valuations were prepared in accordance with the framework of the American Institute of Certified Public Accountants’ Technical Practice Aid, Valuation of Privately-Held Company Equity Securities Issued as Compensation, or the Practice Aid. The Practice Aid identifies various available methods for allocating enterprise value across classes and series of capital stock to determine the estimated fair value of common stock at each valuation date. In addition to considering the results of these third-party valuations, the board of directors considered various objective and subjective factors to determine the fair value of the Company’s equity instruments as of each grant date, which may be later than the most recently available third-party valuation date, including: • the lack of liquidity of our equity as a private company; • the prices of our convertible preferred stock sold to outside investors in arm’s length transactions and the rights, preferences and privileges of our convertible preferred stock as compared to those of our common stock, including the liquidation preferences of our convertible preferred stock; • the progress of our research and development efforts, including the status of preclinical studies and clinical trials for our product candidates; • our stage of development and business strategy and the material risks related to our business and industry; • the achievement of enterprise milestones, including entering into strategic collaborative and license agreements; • the valuation of publicly traded companies in the life sciences and biotechnology sectors, as well as recently completed mergers and acquisitions of peer companies; • any external market conditions affecting the biotechnology industry and trends within the biotechnology industry; • the likelihood of achieving a liquidity event, such as an initial public offering or a sale of our company, given prevailing market conditions; and • the analysis of initial public offerings and the market performance of similar companies in the biotechnology industry. Subsequent to the completion of the IPO, it is no longer necessary for the board of directors to estimate the fair value of the Company’s common stock in connection with its accounting for granted stock options and restricted stock awards, as the fair value of its common stock is determined based on the trading price of its common stock on the Nasdaq Global Select Market. Prior to the completion of its IPO, the Company used a hybrid of the probability-weighted expected returns method (“PWERM”), and the option pricing method (“OPM”), when allocating enterprise value to classes of securities. Under the PWERM, the value of an enterprise and its underlying common stock are estimated based on an analysis of future values for the enterprise, assuming various outcomes. The value of the common stock is based on the probability-weighted present value of expected future investment returns considering each of the possible outcomes and the rights of each class of equity. The future values of the common stock under the various outcomes are discounted back to the valuation date at an appropriate risk-adjusted discount rate and then probability weighted to determine the value for the common stock. The OPM treats common stock and preferred stock as call options on the enterprise’s equity value, with exercise prices based on the liquidation preferences of the preferred stock. Under this method, the common stock has value only if the funds available for distribution to stockholders exceed the value of the liquidation preferences at the time of a liquidity event. The Black-Scholes model is used to price the call option, and the model includes assumptions for the time to liquidity and the volatility of equity value. The hybrid method is a blend of the PWERM and OPM, estimating the probability-weighted value across multiple scenarios and then using the OPM to estimate the allocation of value within one or more of those scenarios. When using the hybrid method, the Company assumed three scenarios: an early IPO scenario, a late IPO scenario and a remain-private scenario. The IPO scenarios reflect an exit or liquidity event by means of a sale of common stock by the Company to the public where the estimated IPO price is based, in part, on a review of recent IPO information of comparable public companies at a similar stage to the Company at the time of their IPO. The comparable IPO companies considered for these scenarios consisted of biopharmaceutical companies at various stages of development ranging from discovery stage to completion of early-stage clinical trials. Additional comparable IPO companies at similar product development stages in the broader biopharmaceutical industry were also considered. The Company converted the estimated future value in an IPO to present value using a risk-adjusted discount rate. The equity value for the remain-private scenario was estimated using the discounted cash flow method or by back-solving to the price of a recently issued preferred stock. In the remain-private scenario, value is allocated to the Company’s equity securities using the OPM. In the OPM, volatility is estimated based on the trading histories of selected guideline public companies. The relative probability of each scenario was determined based on an assessment of then-current market conditions and the Company’s expectations as to the timing and prospects of an IPO. There are significant judgments and estimates inherent in the determination of the fair value of the common stock. These estimates and assumptions include a number of objective and subjective factors, including external market conditions, the prices at which the Company sold shares of preferred stock, the superior rights and preferences of securities senior to the common stock at the time of, and the likelihood of, achieving a liquidity event, such as an IPO or sale of the Company. Significant changes to the key assumptions used in the valuations could result in different fair values of common stock at each valuation date. 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’ (deficit) equity that result from transactions and economic events other than those with stockholders. There was a difference of $ 0.1 million and less than $ 0.1 million between net loss and comprehensive loss presented in the accompanying consolidated financial statements for the years ended December 31, 2021 and 2020 , respectively, which included unrealized gains and 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 p

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2021
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, 2021 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: US Treasury securities $ 61,373 $ — $ 61,373 $ — Corporate debt securities 33,806 — 33,806 — 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: US Treasury securities $ 13,547 $ — $ 13,547 $ — Total available-for-sale securities, long-term $ 13,547 $ — $ 13,547 $ — Balance at Quoted Prices Significant Significant Cash equivalents: Money market mutual funds $ 7,962 $ 7,962 $ — $ — Commercial paper 12,499 — 12,499 — Corporate debt securities 4,001 — 4,001 — Total cash equivalents $ 24,462 $ 7,962 $ 16,500 $ — Available-for-sale securities: US Treasury securities $ 3,027 $ — $ 3,027 $ — Corporate debt securities 1,286 — 1,286 — Commercial paper 19,481 — 19,481 — Certificates of deposit 2,774 — 2,774 — Total available-for-sale securities $ 26,568 $ — $ 26,568 $ — 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. During the years ended December 31, 2021 and 2020 , there were no transfers between Level 1, Level 2 and Level 3.

Available-for-sale Securities

Available-for-sale Securities	12 Months Ended
	Dec. 31, 2021
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, 2021 Amortized Gross Gross Fair Value Available-for-sale securities: US Treasury securities $ 61,450 $ — $ ( 77 ) $ 61,373 Corporate debt securities 33,814 — ( 8 ) 33,806 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: US Treasury securities $ 13,585 $ — $ ( 38 ) $ 13,547 Total available-for-sale securities, long-term $ 13,585 $ — $ ( 38 ) $ 13,547 December 31, 2020 Amortized Gross Gross Fair Value Available-for-sale securities: US Treasury securities $ 3,027 $ — $ — $ 3,027 Corporate debt securities 1,286 — — 1,286 Commercial paper 19,481 1 ( 1 ) 19,481 Certificates of deposit 2,775 — ( 1 ) 2,774 Total available-for-sale securities $ 26,569 $ 1 $ ( 2 ) $ 26,568 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, 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, 2021 , the Company did not hold any investments that matured beyond five years . During the year ended December 31, 2021 , the Company did not sell any available-for-sale securities and therefore did no t recognize any realized gains or losses. The Company had eight investments in available-for-sale securities in an unrealized loss position as of December 31, 2020 with a fair value of $ 17.1 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, 2020, 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. During the year ended December 31, 2020, 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, 2021
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, 2021 2020 Leasehold improvements $ 7,096 $ 7,096 Laboratory equipment 3,339 2,870 Computer equipment and software 212 212 Furniture and fixtures 947 947 Total property and equipment 11,594 11,125 Accumulated depreciation ( 5,983 ) ( 4,788 ) Property and equipment, net $ 5,611 $ 6,337 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 such transaction was a financing transaction as the Company will retain substantially all of the benefits and risks incident to the ownership of the laboratory equipment. The Company further concluded the lease is a capital lease. As such, the Company recorded a capital lease liability in the amount of $ 0.5 million which represents the present value of the Company’s remaining lease payments obligations . As of December 31, 2021, the remaining portion of the capital lease liability of $ 0.2 million is presented as a component of accrued expenses and other current liabilitie s. As of December 31, 2021 , the carrying value of the related assets was $ 0.2 million, net of accumulated amortization of $ 0.3 million w hich is included in the balance of accumulated depreciation presented above. The Company incurred depreciation expense of $ 1.4 million and $ 1.6 million in the years ended December 31, 2021 and 2020 , respectively.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	12 Months Ended
	Dec. 31, 2021
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, 2021 2020 Accrued research and development expenses $ 3,152 $ 680 Accrued payroll and related expenses 2,932 2,381 Accrued other and other current liabilities 1,035 557 Equipment financing, current 213 193 Accrued professional fees 380 1,854 $ 7,712 $ 5,665

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	7. Commitments and Contingencies Lease Obligations In July 2016, the Company entered into an operating lease for its facility. 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. As of December 31, 2021 and 2020 , the lease was secured by a letter of credit in the amount of $ 0.5 million and $ 0.8 million, respectively. In conjunction with the lease, the landlord provided the Company with a $ 5.3 million tenant improvement allowance. The Company concluded that the tenant improvements represent normal tenant improvements, and as such, the Company is capitalizing the costs, as incurred, as leasehold improvement assets. As of December 31, 2021 and 2020 , the Company recorded $ 7.1 million of tenant improvements on the consolidated balance sheets. The proceeds received from the landlord are recorded as an incentive obligation and amortized as a reduction of rent expense over the term of the lease. In September 2019, the Company entered into an operating lease under which the Company leased additional office space from a third-party tenant under a sublease agreement at its current 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 . As of December 31, 2021 and 2020 , the sublease was secured by a letter of credit in the amount of $ 0.5 million and $ 0.6 million, respectively. 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 twenty-four months . Annual base rent is $ 1.1 million for each year during the sublease term. The sublessee is obligated to pay its ratable portion of operating expenses during the sublease term. Subject to the Company’s consent, the sublease provides the sublessee one option to extend up to one year , subject to a 3.0 % rent increase. In May 2021, the subtenant exercised its right to extend the sublease term through October 31, 2022 . Under the exercised sublease term, base rent is $ 1.7 million for each year during the extension. The sublessee provided a security deposit of $ 0.2 million in cash which is presented as a component of other long-term liabilities on the consolidated balance sheets. Payments received under the sublease are recorded as a reduction to rent expense in the consolidated statements of operations and comprehensive income (loss). The Company recorded total rent expense of $ 1.2 million and $ 1.6 million for the years ended December 31, 2021 and 2020 , respectively. Included in the calculation of rent expense was $ 1.2 million and $ 1.2 million of rent expense for the years ended December 31, 2021 and 2020, respectively, related to the operating lease under which the Company is a sublessee. Future minimum rental payments under the operating leases as of December 31, 2021 were as follows (in thousands): Minimum Rental 2022 $ 3,616 2023 3,705 2024 3,795 2025 3,888 2026 3,984 Thereafter 1,357 Total $ 20,345 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”) 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. 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 income (loss). The consolidated financial statements as of December 31, 2021 and 2020 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. 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 income (loss). The consolidated financial statements as of December 31, 2021 and 2020 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”), 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. 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 income (loss). The consolidated financial statements as of December 31, 2021 and 2020 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, 2021 or 2020. 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, 2021, 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.

Restructuring

Restructuring	12 Months Ended
	Dec. 31, 2021
Restructuring and Related Activities [Abstract]
Restructuring	8. Restructuring In January and May 2020, the Company conducted a reduction in force that resulted in the termination of 45 full-time employees. Accordingly, during the year ended December 31, 2020, the Company recorded a restructuring charge of $ 3.5 million, which was comprised of termination benefits including severance, benefits and other payroll-related charges. These accrued restructuring costs are included as a component of accrued expenses and other current liabilities on the consolidated balance sheets. The Company did no t incur any restructuring costs during the year ended December 31, 2021. The following table summarizes the restructuring activity during the year ended December 31, 2021 and 2020 (in thousands): Accrued Balance at December 31, 2019 $ — Restructuring costs incurred 2,919 Termination benefits paid ( 1,496 ) Balance at March 31, 2020 $ 1,423 Restructuring costs incurred 554 Termination benefits paid ( 920 ) Balance at June 30, 2020 $ 1,057 Restructuring costs incurred — Termination benefits paid ( 863 ) Balance at September 30, 2020 $ 194 Restructuring costs incurred — Termination benefits paid ( 186 ) Balance at December 31, 2020 $ 8 Restructuring costs incurred — Termination benefits paid ( 8 ) Balance at March 31, 2021 $ — The following table summarizes the classification of restructuring expense in the consolidated statements of operations and comprehensive income (loss) for the years ended December 31, 2021 and 2020: Year Ended 2021 2020 Research and development $ — $ 2,723 General and administrative — 750 Total restructuring expense $ — $ 3,473 During the first quarter of 2020, the Company entered into retention agreements with certain key employees. Under the terms of these agreements, the Company agreed to make three retention payments to each key employee totaling $ 1.6 million in the aggregate if they remained employed at the Company through specified milestones. The first payments of $ 0.7 million in the aggregate were paid upon execution of the retention agreements. The second payments of $ 0.4 million in the aggregate became due to the key employees upon the closing of the Series D financing in November 2020 (see Note 10). All amounts owed related to the second payments were paid prior to December 31, 2020. The third payments of $ 0.5 million in the aggregate were paid in January 2021, including payments to certain employees who were required to remain employed through January 2022 in order to retain the first and third payments. These prepayments were amortized over the remaining employee service terms under the retention agreements. The first payments are subject to contractual claw-back features which require the repayment of previously paid amounts in the event the employee leaves the Company prior to the achievement of the third payment milestone. During the second quarter of 2020, the Company established additional employee bonuses in the aggregate amount of $ 0.4 million for the majority of employees who were not party to a retention agreement. The bonuses became due upon the closing of the Series D financing in November 2020. All amounts owed related to the additional employee bonuses were paid prior to December 31, 2020.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2021
Equity [Abstract]
Stockholders' Equity	9. Stockholders' Equity As of December 31, 2021, the Company’s Amended and Restated 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. As of December 31, 2020, the Company's Fourth Amended and Restated Certificate of Incorporation authorized the Company to issue 115,000,000 shares of common stock, $ 0.001 par value. Prior to the Company's IPO, the voting, dividend and liquidation rights of the holders of shares of common stock were subject to and qualified by the rights, powers and preferences of the holders of shares of the Company’s convertible preferred stock. 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, 2021 2020 Series A convertible preferred stock — 3,719,410 Series B convertible preferred stock — 989,299 Series C convertible preferred stock — 2,970,149 Series D convertible preferred stock — 5,988,773 Shares reserved for exercise of outstanding stock options under the 2015 Stock 2,540,963 2,686,120 Shares reserved for exercise of outstanding stock options under the 2021 Stock 496,500 — Shares reserved for future awards under the 2015 Stock Incentive Plan — 790,596 Shares reserved for future awards under the 2021 Stock Incentive Plan 1,221,593 — Shares reserved for future awards under the 2021 Employee Stock Purchase Plan 566,037 — Total common stock reserved 4,825,093 17,144,347

Convertible Preferred Stock

Convertible Preferred Stock	12 Months Ended
	Dec. 31, 2021
Temporary Equity Disclosure [Abstract]
Convertible Preferred Stock	10. Convertible Preferred Stock Prior to January 1, 2020, the Company issued 57,758,734 shares of $ 0.001 par value Series A convertible preferred stock (the “Series A Preferred Stock”) for net proceeds of $ 57.7 million, 12,500,000 shares of $ 0.001 par value Series B convertible preferred stock (the “Series B Preferred Stock”) for net proceeds of $ 25.0 million and 27,528,581 shares of $ 0.001 par value Series C convertible preferred stock (the “Series C Preferred Stock”) for net proceeds of $ 55.0 million. In October 2020, the Company amended the certificate of incorporation to increase the authorized number of shares of Series C Preferred Stock and authorize 47,610,763 shares of $ 0.001 par value Series D Preferred Stock for future issuance. Subsequent to the amendment, in October 2020, the Company issued 10,000,000 shares of Series C Preferred Stock to Regeneron in consideration for its entry into an amendment to the collaboration and license agreement (see Note 13). In November 2020, the Company entered into a stock purchase agreement with existing and new investors whereby the Company issued and sold 31,740,554 shares of Series D convertible preferred stock (the “Series D Preferred Stock” and collectively, with the Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock, the “Convertible Preferred Stock”) to investors at a per share price of $ 1.7265 for net proceeds of $ 54.5 million. The Company also had the obligation to sell and the investors had the obligation to purchase an additional 15,870,209 shares of Series D Preferred Stock at a price of $ 1.7265 per share for aggregate proceeds of $ 27.4 million upon the Company’s achievement of the dosing of the first patient in the Company’s planned Phase 1 clinical trial of DB-OTO (the “Second Tranche Closing”). Investors had the right to purchase the additional shares of Series D Preferred Stock at any point prior to the Second Tranche Closing and the Company’s obligation to sell and the investors obligation to purchase expired upon the closing of a qualified financing transaction. In January 2021, investors waived the achievement of the dosing of the first patient in the Phase 1 clinical trial of DB-OTO as a condition of the Second Tranche Closing. In February 2021, the Company issued and sold 15,870,209 shares of Series D Preferred Stock for aggregate net proceeds of $ 27.4 million at the Second Tranche Closing. In connection with the completion of the Company’s IPO on February 17, 2021, all outstanding shares of Convertible Preferred Stock automatically converted into shares of common stock and the Company amended the Certificate of Incorporation, which authorized the Company to issue 5,000,000 shares of $ 0.001 par value undesignated preferred stock. In connection with the issuance of the Series D Preferred Stock, the Company further amended the certificate of incorporation to modify certain of the rights, preference and privileges of the Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock. Specifically, the amended terms included (i) the reduction of the liquidation preferences of the Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock to 51.776 % of their respective values prior to the amendment and (ii) the favorable increase in the conversion prices and conversion ratios for Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock to account for the down round and provide for additional shares upon conversion to compensate the holders for the reduction in liquidation preference. The Company qualitatively assessed the significance of the modifications. Based on the qualitative assessment, the Company concluded the amendment amounted to an extinguishment of the existing Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock. As a result, the Company recorded a gain on extinguishment of the outstanding Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock measured as the difference between the fair value of the respective securities subsequent to the modification and the carrying value immediately before the extinguishment. The gain on extinguishment of $ 103.5 million was recorded to additional paid-in capital and is reflected as an adjustment in net income (loss) allocable to common stockholders used in the calculation of net income per share for the year ended December 31, 2020. The Company considered whether the Second Tranche Closing qualified as a separate freestanding financial instrument. To qualify as a separate freestanding financial instrument, the Second Tranche Closing would need to be (i) legally detachable and (ii) separately exercisable. The Company concluded the Second Tranche Closing was not legally detachable from the Series D Preferred Stock. Therefore, the Second Tranche Closing did not qualify as a separate freestanding financial instrument. The Company assessed each series of Convertible Preferred Stock for any embedded derivatives. The Company determined that each series of Convertible Preferred Stock represented an equity host under FASB ASC Topic 815, Derivatives and Hedging . The Company’s analysis was based on a consideration of all stated and implied substantive terms and features of each hybrid financial instrument and weighing those terms and features on the basis of the relevant facts and circumstances. None of the embedded features in the Convertible Preferred Stock required bifurcation because either they were considered to be clearly and closely related to the preferred equity host, or they did not meet the net settlement characteristic of a derivative. The Company accounts for beneficial conversion features of the Convertible Preferred Stock under FASB ASC Topic 470-20, Debt with Conversion and Other Options . At the time of the issuance of each series of the Convertible Preferred Stock, the Company’s common stock into which each such series of the Convertible Preferred Stock was then convertible had an estimated fair value less than the effective conversion price of each such series of Convertible Preferred Stock. Therefore, there was no intrinsic value on the respective commitment dates. As such, the Company concluded there were no beneficial conversion features associated with the Convertible Preferred Stock. The conversion prices of each series of Convertible Preferred Stock were subject to certain adjustments. To the extent the conversion price of a series of Convertible Preferred Stock was adjusted, the Company would assess whether a beneficial conversion feature existed for such series and would account for such feature in the period such adjustments to the conversion price occurred. In accordance with the guidance in FASB ASC Topic 480, Distinguishing Liabilities from Equity , the Convertible Preferred Stock was classified outside of stockholders’ (deficit) equity because the shares contained redemption features that were not solely within the control of the Company. As it related to the accretion to redemption value, the Convertible Preferred Stock was not then-redeemable, nor was it probable that the instrument would become redeemable, as it was only redeemable upon the occurrence of a contingent event. Accordingly, no accretion was recognized for the Convertible Preferred Stock and it would not be accreted until it was probable that the shares would become redeemable. At December 31, 2020, the occurrence of the contingent events was not considered probable. The Company’s Convertible Preferred Stock consisted of the following (in thousands, except share data): December 31, 2020 Preferred Preferred Carrying Liquidation Common Stock Series A Preferred Stock 57,758,734 57,758,734 $ 16,176 $ 40,284 3,719,410 Series B Preferred Stock 12,500,000 12,500,000 5,700 16,334 989,299 Series C Preferred Stock 37,528,581 37,528,581 16,759 45,457 2,970,149 Series D Preferred Stock 47,610,763 31,740,554 54,456 55,509 5,988,773 155,398,078 139,527,869 $ 93,091 $ 157,584 13,667,631 The Convertible Preferred Stock had the following rights and preferences as of December 31, 2020: Voting Prior to the IPO, the holders of the Convertible Preferred Stock voted as a single class and had one vote per share on general corporate matters. Significant transactions, including the consummation of the sale of the Company or an IPO, acquiring a business or the sale of company assets, redeeming or repurchasing shares, incurring indebtedness, issuing shares or any other series of capital units, declaring or paying dividends, commencing bankruptcy or insolvency actions, amending the research and development plan, or making any material change to the nature of the Company’s business, was required to be approved by at least 60.0 % of existing the preferred stockholders, voting as a single class. The holders of Series D Preferred Stock were entitled to elect up to three directors, and the holders of Convertible Preferred Stock, voting as a single class, had the right to elect up to three directors. Holders of common stock and Convertible Preferred stock voting as a single class were entitled to elect the balance of the total number of directors of the Company. Dividends Dividends accrued on Convertible Preferred Stock from day to day, whether or not earned or declared, and were cumulative, and payable solely upon liquidation, dissolution, winding up of the Company or a deemed liquidation event. Dividends accrued on Series A Preferred Stock at a rate of $ 0.08 per annum per share, on Series B Preferred Stock and Series C Preferred Stock at a rate of $ 0.16 per annum per share, and on Series D Preferred Stock at a rate of $ 0.13812 per annum per share. During the year ended December 31, 2020, dividends accrued on Convertible Preferred Stock totaled $ 12.2 million. On November 2, 2020, concurrent with the issuance and sale of the Company’s Series D Preferred Stock and pursuant to the related amendment to the certificate of incorporation, the dividends accrued on Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock were reduced to 51.776 % of the balance then-accrued and unpaid (the “Pre-Series D Cumulative Dividends”). Thereafter, dividends continued to accrue and at the stated dividend rates (the “Post-Series D Cumulative Dividends”) and the balance of total cumulative dividends was equal to the Pre-Series D Cumulative Dividends plus the Post-Series D Cumulative Dividends. No dividends were declared or paid during the years ended December 31, 2021 or 2020. Cumulative dividends on the Company’s Convertible Preferred Stock consisted of the following (in thousands): December 31, 2020 Series A Preferred Stock $ 10,399 Series B Preferred Stock 3,398 Series C Preferred Stock 6,623 Series D Preferred Stock 709 $ 21,129 During the year ended December 31, 2021, $ 2.3 million of dividends accrued prior to the completion of the IPO. Subsequent to the completion of the IPO, no shares of Convertible Preferred Stock were issued or outstanding and therefore no dividends accrued. Conversion Shares of Convertible Preferred Stock were convertible at any time at the option of the holder into such number of shares as is determined by dividing the original issuance price by the conversion price in effect at the time. Original issue prices were $ 1.00 per share for Series A Preferred Stock, $ 2.00 per share for Series B Preferred Stock and Series C Preferred Stock, and $ 1.7265 per share for Series D Preferred Stock. As of December 31, 2020, the conversion price for Series A Preferred Stock was $ 15.529 per share, the conversion price for Series B Preferred Stock and C Preferred Stock was $ 25.27 per share and the conversion price for Series D Preferred Stock was $ 9.15 per share. The original issue price was subject in each case to certain adjustments to reflect the issuance of common stock, options, warrants, or other rights to subscribe for or to purchase shares of the Company’s common stock for consideration per share less than the conversion price then in effect and subsequent stock dividends and stock splits. As of December 31, 2020, all outstanding shares of Convertible Preferred Stock were to automatically convert upon the completion of either an IPO at a price per share of at least $ 13.7259 , as adjusted for stock splits or stock dividends, resulting in gross proceeds to the Company of at least $ 75.0 million or the vote or written consent of 60 % the holders of the majority of the then-outstanding shares of Convertible Preferred Stock on an as-converted to common stock basis. Liquidation Preference Holders of Convertible Preferred Stock were entitled to a liquidation preference in the event of any voluntary or involuntary liquidation, dissolution, or winding up of the Company. In the case of Series D Preferred Stock, the liquidation preference was equal to the greater of (i) $ 1.7265 per share plus any dividends accrued but unpaid, together with any other dividends declared but unpaid or (ii) any such amount per share as would have been payable had all shares of Series D Preferred Stock been converted into common stock immediately prior to such liquidation event. In the case of Series B Preferred Stock and Series C Preferred Stock, after the payment of preferential amounts required to be paid to the holders of Series D Preferred Stock, the liquidation preference was equal to the greater of (i) the sum of $ 1.03552 per share, plus the respective Pre-Series D Cumulative Dividends accrued but unpaid, whether or not declared, plus the respective Post-Series D Cumulative Dividends accrued but unpaid, whether or not declared, together with any other dividends declared but unpaid or (ii) any such amount per share as would have been payable had all shares of Series B Preferred Stock and Series C Preferred Stock been converted into common stock immediately prior to such liquidation event. In the case of Series A Preferred Stock, after the payment of preferential amounts required to be paid to the holders of Series D Preferred Stock and Series B Preferred Stock and Series C Preferred Stock, the liquidation preference was equal to the greater of (i) the sum of $ 0.51776 per share, plus the respective Pre-Series D Cumulative Dividends accrued but unpaid, whether or not declared, plus the respective Post-Series D Cumulative Dividends accrued but unpaid, whether or not declared, together with any other dividends declared but unpaid or (ii) any such amount per share as would have been payable had all shares of Series A Preferred Stock been converted into common stock immediately prior to such liquidation event. A deemed liquidation event was defined as a merger (unless the shares of capital stock prior to the transaction represent the majority of the post-merger voting rights) or the sale or transfer of substantially all of the assets of the Company unless (i) the holders of at least 60.0% of the then outstanding shares of Convertible Preferred Stock on an as-converted to common stock basis and (ii) the holders of a majority of the then outstanding Series D Preferred Stock on an as-converted to common stock basis, elected otherwise. After all preferential payments, the common stockholders were entitled to share in the remaining assets of the Company on a pro rata basis. Redemption The Convertible Preferred Stock did not have any redemption rights that were at the election of the holder. However, the Convertible Preferred Stock was redeemable upon the occurrence of certain contingent events, including a deemed liquidation event. Rights and Preferences Specific to the Series B Convertible Preferred Shares The holder of Series B Preferred Stock had a right of first offer with respect to the Company’s sale of new securities, including the common stock offered in an IPO, allowing the holder of Series B Preferred Stock to purchase up to the lesser of (1) one-third of the aggregate number of new securities then being offered and (2) such number of new securities such that, immediately following the closing of such sale, the holder of Series B Preferred Stock would own 25 % of the Company’s outstanding capital stock on a fully diluted basis immediately following the closing of such sale. The right of first offer granted to the holder of Series B Preferred Stock preceded the first offer rights of holders of Series A Preferred Stock and Series C Preferred Stock. Additionally, the holder had the right to purchase, in a side-by-side private placement at the time of a qualified IPO, such number of new shares of Common Stock such that, immediately following the closing of such IPO, the holder would own 30 % of the Company’s outstanding capital stock on a fully diluted basis.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2021
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	11. Stock-Based Compensation 2015 Stock Incentive Plan As of December 31, 2020, there were 3,930,701 shares of common stock authorized for issuance under the 2015 Stock Incentive Plan (the “2015 Plan”) under which the Company could grant equity awards to eligible employees, officers, directors, consultants and advisors. Subsequent to the pricing of the Company’s IPO on February 11, 2021, no further awards were to be made under the 2015 Plan; however, awards outstanding under the 2015 Plan continue to be governed by the 2015 Plan. 2021 Stock Incentive Plan In January 2021, the Board of Directors of the Company approved, and in February 2021 the Company's stockholders approved, the 2021 Stock Option and Incentive Plan (the “2021 Plan”), which became effective immediately prior to the pricing of the Company’s IPO. The 2021 Plan allows the Company to grant stock options, stock appreciation rights, restricted stock, restricted stock units and other stock-based awards for the purchase of that number of shares of Common Stock equal to the sum of (i) 849,056 shares of Common Stock plus (ii) such additional number of shares of Common Stock (up to 3,529,250 shares of Common Stock as is equal to the sum of (x) the number of shares of Common Stock reserved for issuance under the 2015 Plan that remain available for issuance under the 2015 Plan immediately prior to the effectiveness of the Company’s IPO and (y) the number shares of Common Stock subject to awards under the 2015 Plan which awards expire, terminate or are otherwise surrendered, canceled, forfeited or repurchased by the Corporation at their original issuance price pursuant to a contractual repurchase right, and pursuant to which the number of shares of Common Stock that may be issued under the 2021 Plan shall be automatically increased as provided in the 2021 Plan. As of December 31, 2021 , 496,500 shares were reserved for outstanding awards granted under the 2021 Plan and 1,221,593 shares remained available for issuance. Stock options issued under the 2021 Plan expire ten years from the date of grant. The number of shares available for future grant does not include the shares added to the 2021 Plan reserve on January 1, 2022 as a result of an automatic increase in the shares available under the 2021 Plan in accordance with its terms. 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. Awards issued under the 2021 Plan generally vest over a 4-year period with vesting of awards subject to the recipient’s continued employment or service . Shares that expire, are terminated, repurchased, surrendered or canceled under the 2021 Plan without having been fully exercised are available for future awards under the 2021 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. 2021 Employee Stock Purchase Plan In January 2021, the Board of Directors of the Company approved, and in February 2021 the Company’s stockholders approved, the 2021 Employee Stock Purchase Plan (the “2021 ESPP”). Under the 2021 ESPP, the Company is authorized to issue 566,037 shares of our common stock, subject to annual increases, and eligible employees are able to purchase shares of common stock at a specified discount. As of December 31, 2021 , no shares have been issued under the 2021 ESPP and as such, 566,037 shares remained available for issuance under the 2021 ESPP. The number of shares available for issuance under the 2021 ESPP does not include the shares added to the 2021 ESPP reserve on January 1, 2022 as a result of an automatic increase in the shares available under the 2021 ESPP in accordance with its terms. Restricted Stock A summary of the Company’s restricted stock activity and related information is as follows: Number of Weighted Unvested as of December 31, 2020 52,741 $ 19.10 Vested ( 34,759 ) 17.21 Repurchased ( 777 ) 0.53 Canceled/Forfeited ( 4,668 ) 20.96 Unvested as of December 31, 2021 12,537 $ 24.79 The aggregate fair value of restricted stock awards that vested during the years ended December 31, 2021 and 2020 was $ 0.6 million and $ 1.4 million, respectively. No restricted stock awards were issued upon the early exercise of stock options during the years ended December 31, 2021 and 2020. As of December 31, 2021 , total unrecognized compensation cost related to the unvested restricted stock awards was approximately $ 0.3 million, which is expected to be recognized over a weighted-average period of 0.5 years. 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, 2020 2,686,120 $ 4.53 9.9 $ 3,781 Granted 681,200 9.25 Exercised ( 72,161 ) 4.40 Cancelled/forfeited ( 257,696 ) 7.50 Outstanding as of December 31, 2021 3,037,463 $ 5.34 8.9 $ 629 Exercisable as of December 31, 2021 1,160,914 $ 4.96 8.7 $ 271 Vested and expected to vest as of December 31, 2021 3,037,463 $ 5.34 8.9 $ 629 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, 2021 2020 Risk-free interest rate 0.82 - 1.34 % 0.39 - 0.53 % Expected annual dividend yield 0.00 % 0.00 % Expected stock price volatility 85.4 - 89.3 % 89.0 - 90.7 % Expected term (in years) 5.0 - 6.1 5.0 - 6.1 The weighted-average grant date fair value per share of options granted during the year ended December 31, 2021 and 2020 was $ 6.99 and $ 3.19 , respectively. The intrinsic value of options exercised during the year ended December 31, 2021 and 2020 was $ 0.2 million and $ 0.1 million. As of December 31, 2021 , total unrecognized compensation cost related to the unvested stock options was approximately $ 7.2 million, which is expected to be recognized over a weighted-average period of 2.92 years. Stock-Based Compensation Expense The following table presents the components and classification of stock-based compensation expense (in thousands): Year Ended December 31, 2021 2020 Research and development $ 1,237 $ 1,239 General and administrative 1,580 1,575 Total stock-based compensation expense $ 2,817 $ 2,814 No related income tax benefits were recorded during the years ended December 31, 2021 or 2020 .

Net Income (Loss) per Share

Net Income (Loss) per Share	12 Months Ended
	Dec. 31, 2021
Earnings Per Share [Abstract]
Net Income (Loss) per Share	12. Net Income (Loss) per Share The following is a reconciliation of weighted-average shares of common stock outstanding used in calculating basic net income per share to weighted-average shares of common stock outstanding used in calculating diluted net loss per share: Year Ended December 31, 2021 2020 Weighted-average shares of common stock outstanding, basic 21,733,960 476,700 Add: Effect of dilutive securities Series B Preferred Stock — 365,541 Series C Preferred Stock — 953,619 Total 21,733,960 1,795,860 Weighted-average shares of common stock outstanding, basic and diluted did not require reconciliation for the year ended December 31, 2021 as all outstanding shares of common stock equivalents were excluded from the calculation of diluted net loss per share attributable to common stockholders. 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, 2021 2020 Series A Preferred Stock — 3,719,410 Series B Preferred Stock — — Series C Preferred Stock — — Series D Preferred Stock — 5,988,773 Outstanding stock options 3,037,463 2,686,120 Unvested restricted stock 12,537 52,741 3,050,000 12,447,044

License and Collaboration Agree

License and Collaboration Agreement with Regeneron	12 Months Ended
	Dec. 31, 2021
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 a license and collaboration agreement with Regeneron (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 will oversee 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 cost needed to achieve 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 “Amended Agreement”) 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 amendment, the Company issued 10,000,000 shares of Series C Preferred Stock to Regeneron in consideration for its entry into the 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 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 “CDMO Initiation Fee”). 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 investigational new drug (“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 is obligated to pay the Company an extension fee of $ 10.0 million in the fourth quarter of 2022. As of December 31, 2021,the Company had an unbilled receivable of $ 11.4 million related to the remaining balance of reimbursable third-party costs related to 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, 2021, the Company had received an aggregate of $ 5.5 million in milestone payments from Regeneron pursuant to the collaboration. As of December 31, 2021, 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. 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 income (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 was 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 income (loss) based on the Company’s progress towards completion of its research activities under the research plan. Amended Agreement The Company concluded that both the Company and Regeneron remain active participants in the research and development activities under the 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, 2020, the transaction price under the collaboration was $ 35.8 million consisting of (i) $ 25.0 million received pursuant to the Regeneron Agreement, (ii) $ 0.3 million received to fund the ongoing research plan, (iii) $ 4.4 million for the first pre-IND milestone achieved in November 2020, $ 0.5 million of which was received as the CDMO Initiation Fee in October 2020, and (iv) $ 10.5 million in reimbursements for third-party costs related to IND-enabling studies for DB-OTO, partially offset by the fair value of the Series C 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 $ 11.0 million and $ 2.0 million of contra-research and development expense for the year ended December 31, 2021 and 2020, respectively. The contra-research and development recorded in the year ended December 31, 2021 included a cumulative catch-up amount of approximately $ 0.5 million related to the achievement of the second pre-IND milestone, which was fully constrained as of December 31, 2020, and a cumulative catch-up amount of $ 4.8 million related to the increase in transaction price related to the extension in November 2021. The cumulative-catch up amounts and progress achieved in the period were partially offset by increases to the Company's cost estimates related to completing the performance obligation. As of December 31, 2021 and 2020 , there was $ 8.1 million and $ 11.0 million of deferred collaboration liability classified in current liabilities, respectively, and $ 16.4 million and $ 4.2 million of deferred collaboration liability classified in long-term liabilities, respectively. As of December 31, 2021 , the Company had $ 11.4 million of unbilled accounts receivable, which is classified in accounts receivable from related party on the consolidated balance sheets, which includes $ 1.4 million of expected cost reimbursement from Regeneron for costs incurred related to the Company's IND enabling study for DB-OTO and the $ 10.0 million amount Regeneron is obligated to pay the Company in November 2022 related to the research term extension .

Employee Retirement_Savings Pla

Employee Retirement/Savings Plan	12 Months Ended
	Dec. 31, 2021
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 year ended December 31, 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 $ 0.3 million for the year ended December 31, 2021 . The Company did no t make matching contributions for the year ended December 31, 2020.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	15. Income Taxes 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. For financial reporting purposes, loss before provision for income taxes, includes the following components (in thousands): Year Ended December 31, 2021 2020 Domestic $ ( 50,825 ) $ ( 37,501 ) Foreign 799 ( 1,836 ) Loss before income taxes $ ( 50,026 ) $ ( 39,337 ) The provision (benefit) for income taxes consists of the following (in thousands): Year Ended December 31, 2021 2020 Current: Federal $ — $ — State — — Foreign 1,797 — Total Current 1,797 — Deferred: Federal — — State — — Foreign — — Total Deferred — — Loss before income taxes $ 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, 2021 2020 Expected income tax benefit at the federal statutory rate 21.0 % 21.0 % State taxes 5.8 5.8 Foreign taxes ( 0.5 ) ( 1.0 ) Change in valuation allowance ( 27.2 ) ( 25.7 ) Research and development tax credits 0.7 0.9 Foreign rate differential ( 0.1 ) 0.4 Stock compensation ( 0.5 ) ( 0.8 ) Uncertain Tax Position ( 2.9 ) — Permanent differences 0.1 ( 0.6 ) Effective income tax rate ( 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, 2021 2020 Deferred tax assets: Federal, state and foreign net operating loss carryforwards $ 53,075 $ 41,379 Research and development and other credits 1,840 1,333 Deferred rent and lease incentive obligation 1,321 1,506 Accrued expenses and other 1,551 1,063 Total gross deferred tax assets 57,787 45,281 Valuation allowance ( 57,013 ) ( 44,305 ) Total deferred tax assets $ 774 $ 976 Deferred tax liabilities: Depreciation of fixed assets ( 774 ) ( 976 ) Total deferred tax liabilities $ ( 774 ) $ ( 976 ) 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, 2021. Management considered the Company’s cumulative net losses and concluded as of December 31, 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, 2021. Changes in the valuation allowance for deferred tax assets were as follows (in thousands): Year Ended December 31, 2021 2020 Valuation allowance at beginning of the year $ 44,305 $ 34,203 Increases recorded to income tax provision 12,708 10,102 Valuation allowance at end of year $ 57,013 $ 44,305 Subject to the limitations described below, at December 31, 2021 and 2020, the Company had U.S. federal net operating loss carryforwards of approximately $ 196.3 million and $ 148.7 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, 2021, the Company had net operating losses of $ 154.6 million which had an indefinite life. As of December 31, 2021 and 2020, the Company had state net operating loss carryforwards of approximately $ 187.9 million and $ 146.0 million, respectively, to offset future state taxable income, which will begin to expire in 2035 . Subject to the limitations described below, at December 31, 2021 and 2020, the Company had federal research and development tax credit carryforwards of $ 1.2 million and $ 0.8 million, respectively, which expire beginning in 2033 . As of December 31, 2021 and 2020, the Company had state research and development tax credit carryforwards of $ 0.8 million and $ 0.5 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, 2021, the Company had $ 2.1 million of gross unrecognized tax benefits, of which $ 1.2 million would affect income tax expense if recognized, before consideration of the Company’s valuation allowance. As of December 31, 2021, the gross unrecognized tax benefits included $ 0.9 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. As of December 31, 2021, the Company has accrued penalties and provisions for interest of $ 0.4 million. As of December 31, 2020 the Company had no accrued penalties and provisions for interest. A reconciliation of the gross unrecognized tax benefits are as follows (in thousands): Year Ended December 31, 2021 2020 Unrecognized tax benefits at the beginning of the period $ — $ — Increases for current tax positions 2,084 — Increases for previous tax positions — — Decreases for previous tax positions — — Unrecognized tax benefits at the end of the period $ 2,084 $ —

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2021
Related Party Transactions [Abstract]
Related Party Transactions	16. Related Party Transactions Regeneron is an investor in and related party of the Company. In October 2020, the Company issued 10,000,000 shares of Series C Preferred Stock in consideration for its entry into the amendment to the collaboration agreement with Regeneron (see Note 10). During the years ended December 31, 2021 and 2020 , the Company recognized $ 11.0 million and $ 2.0 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 income (loss). As of December 31, 2021 and 2020 , the Company had $ 11.4 million and $ 1.2 million, respectively, of unbilled receivables due from Regeneron (see Note 13). The Company did not have any amounts due to Regeneron. For the years ended December 31, 2021 and 2020, the Company recorded expenses of $ 0.2 million and $ 0.1 million, respectively, of consulting services provided by an entity affiliated with a shareholder of the Company and a member of the Board. The Company terminated its prior arrangement with the entity affiliated with a shareholder of the Company and member of the Board effective December 31, 2021.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2021
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.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2021
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, equity-based compensation, 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, and the accrual of research and development expenses. 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 is mainly comprised of corporate obligations and money market accounts invested in U.S. Treasury securities. 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 other assets on the consolidated balance sheets. Cash, cash equivalents and restricted cash consisted of the following (in thousands): December 31, 2021 2020 Cash and cash equivalents $ 36,455 $ 27,742 Restricted cash 1,128 1,476 Total cash, cash equivalents and restricted cash as shown on the statement $ 37,583 $ 29,218
Available-For-Sale Securities	Available-For-Sale Securities Available-for-sale securities primarily consist of corporate obligations, agency bonds and U.S. Treasury 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 income (loss), which is a separate component of stockholders’ (deficit) 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 income (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 investment-grade 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, 2021 and 2020, 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, 2021, and 2020 , 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, 2021 and 2020 .
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, 2021 and 2020 , 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.
Deferred Offering Costs	Deferred Offering Costs The Company capitalizes certain legal, professional, accounting and other third-party fees that are directly associated with in-process equity financings as deferred offering costs until the related financings are consummated. After consummation of the equity financing, such costs are reclassified as a reduction to additional paid-in capital generated as a result of the related financing. Should an in-process equity financing be abandoned, the deferred offering costs will be expensed immediately as a charge to operating expenses in the consolidated statements of operations and comprehensive income (loss). Deferred offering costs are presented as a component of other assets on the consolidated balance sheets. As of December 31, 2021, the Company had no deferred offering costs. As of December 31, 2020, the Company capitalized $ 1.6 million of deferred offering costs related to the IPO of its common stock.
Deferred Rent	Deferred Rent The Company’s operating lease agreements include scheduled rent escalations over the lease term, as well as a tenant improvement allowance provided to the Company upon execution of the lease or as certain tenant improvement costs are incurred. Rent expense is recognized on a straight-line basis over the term of the lease. Tenant improvement allowances are amortized as earned on a straight-line basis over the term of the lease as a reduction to rent expense. Deferred rent consists of the difference between cash payments and the recognition of rent expense on a straight-line basis over the term of the lease and the unamortized portion of tenant improvement allowances, if applicable.
Convertible Preferred Stock	Convertible Preferred Stock The Company records all convertible preferred stock upon issuance at its respective fair value or original issuance price less issuance costs, as stipulated by its terms. The Company classifies its convertible preferred stock outside of stockholders’ equity (deficit) as the redemption of such shares is outside the Company’s control. The Company does not adjust the carrying value of the convertible preferred stock to redemption value until the contingent events are considered probable of occurring.
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, facilities costs and laboratory supplies, depreciation, manufacturing expenses and external costs of outside vendors engaged to conduct preclinical and clinical development activities. 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 income (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 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 and founders, generally in the form of stock options and restricted stock. 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 primarily issues stock options and restricted stock with service-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. The Company has no awards with performance-based or 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 income (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 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 granted with service-based vesting conditions 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. Prior to the completion of its IPO, given the absence of an active market for our common stock, the fair values of the shares of common stock underlying its stock-based awards were determined on each grant date by the Company’s board of directors with input from management, considering its most recently available third-party valuations of its common stock and the board of director’s assessment of additional objective and subjective factors that it believed were relevant and which may have changed from the date of the most recent valuation through the grant date. Historically, these independent third-party valuations of its equity instruments were performed contemporaneously with identified value inflection points. The third-party valuations were prepared in accordance with the framework of the American Institute of Certified Public Accountants’ Technical Practice Aid, Valuation of Privately-Held Company Equity Securities Issued as Compensation, or the Practice Aid. The Practice Aid identifies various available methods for allocating enterprise value across classes and series of capital stock to determine the estimated fair value of common stock at each valuation date. In addition to considering the results of these third-party valuations, the board of directors considered various objective and subjective factors to determine the fair value of the Company’s equity instruments as of each grant date, which may be later than the most recently available third-party valuation date, including: • the lack of liquidity of our equity as a private company; • the prices of our convertible preferred stock sold to outside investors in arm’s length transactions and the rights, preferences and privileges of our convertible preferred stock as compared to those of our common stock, including the liquidation preferences of our convertible preferred stock; • the progress of our research and development efforts, including the status of preclinical studies and clinical trials for our product candidates; • our stage of development and business strategy and the material risks related to our business and industry; • the achievement of enterprise milestones, including entering into strategic collaborative and license agreements; • the valuation of publicly traded companies in the life sciences and biotechnology sectors, as well as recently completed mergers and acquisitions of peer companies; • any external market conditions affecting the biotechnology industry and trends within the biotechnology industry; • the likelihood of achieving a liquidity event, such as an initial public offering or a sale of our company, given prevailing market conditions; and • the analysis of initial public offerings and the market performance of similar companies in the biotechnology industry. Subsequent to the completion of the IPO, it is no longer necessary for the board of directors to estimate the fair value of the Company’s common stock in connection with its accounting for granted stock options and restricted stock awards, as the fair value of its common stock is determined based on the trading price of its common stock on the Nasdaq Global Select Market. Prior to the completion of its IPO, the Company used a hybrid of the probability-weighted expected returns method (“PWERM”), and the option pricing method (“OPM”), when allocating enterprise value to classes of securities. Under the PWERM, the value of an enterprise and its underlying common stock are estimated based on an analysis of future values for the enterprise, assuming various outcomes. The value of the common stock is based on the probability-weighted present value of expected future investment returns considering each of the possible outcomes and the rights of each class of equity. The future values of the common stock under the various outcomes are discounted back to the valuation date at an appropriate risk-adjusted discount rate and then probability weighted to determine the value for the common stock. The OPM treats common stock and preferred stock as call options on the enterprise’s equity value, with exercise prices based on the liquidation preferences of the preferred stock. Under this method, the common stock has value only if the funds available for distribution to stockholders exceed the value of the liquidation preferences at the time of a liquidity event. The Black-Scholes model is used to price the call option, and the model includes assumptions for the time to liquidity and the volatility of equity value. The hybrid method is a blend of the PWERM and OPM, estimating the probability-weighted value across multiple scenarios and then using the OPM to estimate the allocation of value within one or more of those scenarios. When using the hybrid method, the Company assumed three scenarios: an early IPO scenario, a late IPO scenario and a remain-private scenario. The IPO scenarios reflect an exit or liquidity event by means of a sale of common stock by the Company to the public where the estimated IPO price is based, in part, on a review of recent IPO information of comparable public companies at a similar stage to the Company at the time of their IPO. The comparable IPO companies considered for these scenarios consisted of biopharmaceutical companies at various stages of development ranging from discovery stage to completion of early-stage clinical trials. Additional comparable IPO companies at similar product development stages in the broader biopharmaceutical industry were also considered. The Company converted the estimated future value in an IPO to present value using a risk-adjusted discount rate. The equity value for the remain-private scenario was estimated using the discounted cash flow method or by back-solving to the price of a recently issued preferred stock. In the remain-private scenario, value is allocated to the Company’s equity securities using the OPM. In the OPM, volatility is estimated based on the trading histories of selected guideline public companies. The relative probability of each scenario was determined based on an assessment of then-current market conditions and the Company’s expectations as to the timing and prospects of an IPO. There are significant judgments and estimates inherent in the determination of the fair value of the common stock. These estimates and assumptions include a number of objective and subjective factors, including external market conditions, the prices at which the Company sold shares of preferred stock, the superior rights and preferences of securities senior to the common stock at the time of, and the likelihood of, achieving a liquidity event, such as an IPO or sale of the Company. Significant changes to the key assumptions used in the valuations could result in different fair values of common stock at each valuation date.
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’ (deficit) equity that result from transactions and economic events other than those with stockholders. There was a difference of $ 0.1 million and less than $ 0.1 million between net loss and comprehensive loss presented in the accompanying consolidated financial statements for the years ended December 31, 2021 and 2020 , respectively, which included unrealized gains and 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 income (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. As there is no authoritative guidance under GAAP for accounting for grants to for-profit business entities, the Company accounts for the grant by analogy to International Accounting Standards 20 – Accounting for Government Grants and Disclosure of Government Assistance (“IAS 20”). During the fourth quarter of 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 for in the CARES Act and it was reasonably assured that it will receive the employee retention credit. The employee retention credit is recorded in research and development expenses and general and administrative expenses in the manner in which the qualified wages and related costs were classified.
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. As there is no authoritative guidance under GAAP for accounting for grants to for-profit business entities, the Company accounts for the grant by analogy to IAS 20. 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, 2021 and 2020 , respectively, the Company recorded $ 0.6 million and $ 0.5 million 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 Issued Accounting Pronouncement	Recently Issued Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-02 , Leases (Topic 842), Amendments to the FASB Accounting Standards Codification (“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. This guidance is effective for the Company on January 1, 2022, with early adoption permitted. The Company is currently assessing the potential impact that ASC 842 may have on its consolidated financial statements and related disclosures. 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 most significant impacts of adoption will include: (i) the recognition of operating lease right-of-use assets and lease liabilities arising from its leases of office and laboratory space as of January 1, 2022; (ii) the derecognition of deferred rent and unamortized tenant incentives as of January 1, 2022; (iii) the recognition of a finance lease right-of-use asset and lease liability arising from its lease of laboratory equipment as of January 1, 2022; (iv) the derecognition of capital lease liabilities and the carrying value of the related laboratory equipment as of January 1, 2022; and (v) new and expanded disclosure requirements which will first be presented in its Form 10-Q for the quarterly period ending March 31, 2022. 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, with early adoption permitted. The Company is currently evaluating the potential impact that ASU 2016-13 may have on its consolidated financial statements and related disclosures. In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740)—Simplifying the Accounting for Income Taxes (“ASU 2019-12”), as part of its initiative to reduce complexity in the accounting standards. The amendments in ASU 2019-12 eliminate certain exceptions related to the approach for intraperiod 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 the accounting for income taxes. ASU 2019-12 is effective for the Company on January 1, 2022, with early adoption permitted. The Company does not expect that the adoption of ASU 2019-12 will have a material impact on its 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. 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) . This standard will have an effective and transition date of January 1, 2022. This standard 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. The standard 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. The standard additionally provides guidance on measuring and recognizing the effect of a modification or an exchange. The Company does not currently expect the adoption of this standard to have a material impact on the Company's consolidated financial statements. In November 2021, the FASB issued ASU No. 2021-10, Government Assistance (Topic 832): Disclosures by Business Entities about Government Assistance . This standard has an effective and transition date of January 1, 2022. This standard increases the transparency of transactions with the government that are accounted for by applying a grant or contribution accounting model, and 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. This standard 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 does not currently expect the adoption of this standard to have a material impact on the Company's consolidated financial statements.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2021
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, 2021 2020 Cash and cash equivalents $ 36,455 $ 27,742 Restricted cash 1,128 1,476 Total cash, cash equivalents and restricted cash as shown on the statement $ 37,583 $ 29,218
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

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2021
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, 2021 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: US Treasury securities $ 61,373 $ — $ 61,373 $ — Corporate debt securities 33,806 — 33,806 — 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: US Treasury securities $ 13,547 $ — $ 13,547 $ — Total available-for-sale securities, long-term $ 13,547 $ — $ 13,547 $ — Balance at Quoted Prices Significant Significant Cash equivalents: Money market mutual funds $ 7,962 $ 7,962 $ — $ — Commercial paper 12,499 — 12,499 — Corporate debt securities 4,001 — 4,001 — Total cash equivalents $ 24,462 $ 7,962 $ 16,500 $ — Available-for-sale securities: US Treasury securities $ 3,027 $ — $ 3,027 $ — Corporate debt securities 1,286 — 1,286 — Commercial paper 19,481 — 19,481 — Certificates of deposit 2,774 — 2,774 — Total available-for-sale securities $ 26,568 $ — $ 26,568 $ —

Available-for-sale Securities (

Available-for-sale Securities (Tables)	12 Months Ended
	Dec. 31, 2021
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, 2021 Amortized Gross Gross Fair Value Available-for-sale securities: US Treasury securities $ 61,450 $ — $ ( 77 ) $ 61,373 Corporate debt securities 33,814 — ( 8 ) 33,806 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: US Treasury securities $ 13,585 $ — $ ( 38 ) $ 13,547 Total available-for-sale securities, long-term $ 13,585 $ — $ ( 38 ) $ 13,547 December 31, 2020 Amortized Gross Gross Fair Value Available-for-sale securities: US Treasury securities $ 3,027 $ — $ — $ 3,027 Corporate debt securities 1,286 — — 1,286 Commercial paper 19,481 1 ( 1 ) 19,481 Certificates of deposit 2,775 — ( 1 ) 2,774 Total available-for-sale securities $ 26,569 $ 1 $ ( 2 ) $ 26,568

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment, Net	Property and equipment, net consisted of the following (in thousands): December 31, 2021 2020 Leasehold improvements $ 7,096 $ 7,096 Laboratory equipment 3,339 2,870 Computer equipment and software 212 212 Furniture and fixtures 947 947 Total property and equipment 11,594 11,125 Accumulated depreciation ( 5,983 ) ( 4,788 ) Property and equipment, net $ 5,611 $ 6,337

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	12 Months Ended
	Dec. 31, 2021
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, 2021 2020 Accrued research and development expenses $ 3,152 $ 680 Accrued payroll and related expenses 2,932 2,381 Accrued other and other current liabilities 1,035 557 Equipment financing, current 213 193 Accrued professional fees 380 1,854 $ 7,712 $ 5,665

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rental Payments	Future minimum rental payments under the operating leases as of December 31, 2021 were as follows (in thousands): Minimum Rental 2022 $ 3,616 2023 3,705 2024 3,795 2025 3,888 2026 3,984 Thereafter 1,357 Total $ 20,345

Restructuring (Tables)

Restructuring (Tables)	12 Months Ended
	Dec. 31, 2021
Restructuring and Related Activities [Abstract]
Summary of Restructuring Activity	The following table summarizes the restructuring activity during the year ended December 31, 2021 and 2020 (in thousands): Accrued Balance at December 31, 2019 $ — Restructuring costs incurred 2,919 Termination benefits paid ( 1,496 ) Balance at March 31, 2020 $ 1,423 Restructuring costs incurred 554 Termination benefits paid ( 920 ) Balance at June 30, 2020 $ 1,057 Restructuring costs incurred — Termination benefits paid ( 863 ) Balance at September 30, 2020 $ 194 Restructuring costs incurred — Termination benefits paid ( 186 ) Balance at December 31, 2020 $ 8 Restructuring costs incurred — Termination benefits paid ( 8 ) Balance at March 31, 2021 $ —
Summary of Restructuring Expense	The following table summarizes the classification of restructuring expense in the consolidated statements of operations and comprehensive income (loss) for the years ended December 31, 2021 and 2020: Year Ended 2021 2020 Research and development $ — $ 2,723 General and administrative — 750 Total restructuring expense $ — $ 3,473

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2021
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, 2021 2020 Series A convertible preferred stock — 3,719,410 Series B convertible preferred stock — 989,299 Series C convertible preferred stock — 2,970,149 Series D convertible preferred stock — 5,988,773 Shares reserved for exercise of outstanding stock options under the 2015 Stock 2,540,963 2,686,120 Shares reserved for exercise of outstanding stock options under the 2021 Stock 496,500 — Shares reserved for future awards under the 2015 Stock Incentive Plan — 790,596 Shares reserved for future awards under the 2021 Stock Incentive Plan 1,221,593 — Shares reserved for future awards under the 2021 Employee Stock Purchase Plan 566,037 — Total common stock reserved 4,825,093 17,144,347

Convertible Preferred Stock (Ta

Convertible Preferred Stock (Tables)	12 Months Ended
	Dec. 31, 2021
Temporary Equity Disclosure [Abstract]
Schedule of Convertible Preferred Stock	The Company’s Convertible Preferred Stock consisted of the following (in thousands, except share data): December 31, 2020 Preferred Preferred Carrying Liquidation Common Stock Series A Preferred Stock 57,758,734 57,758,734 $ 16,176 $ 40,284 3,719,410 Series B Preferred Stock 12,500,000 12,500,000 5,700 16,334 989,299 Series C Preferred Stock 37,528,581 37,528,581 16,759 45,457 2,970,149 Series D Preferred Stock 47,610,763 31,740,554 54,456 55,509 5,988,773 155,398,078 139,527,869 $ 93,091 $ 157,584 13,667,631
Schedule of Cumulative Dividends	Cumulative dividends on the Company’s Convertible Preferred Stock consisted of the following (in thousands): December 31, 2020 Series A Preferred Stock $ 10,399 Series B Preferred Stock 3,398 Series C Preferred Stock 6,623 Series D Preferred Stock 709 $ 21,129

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2021
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, 2020 52,741 $ 19.10 Vested ( 34,759 ) 17.21 Repurchased ( 777 ) 0.53 Canceled/Forfeited ( 4,668 ) 20.96 Unvested as of December 31, 2021 12,537 $ 24.79
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, 2020 2,686,120 $ 4.53 9.9 $ 3,781 Granted 681,200 9.25 Exercised ( 72,161 ) 4.40 Cancelled/forfeited ( 257,696 ) 7.50 Outstanding as of December 31, 2021 3,037,463 $ 5.34 8.9 $ 629 Exercisable as of December 31, 2021 1,160,914 $ 4.96 8.7 $ 271 Vested and expected to vest as of December 31, 2021 3,037,463 $ 5.34 8.9 $ 629
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, 2021 2020 Risk-free interest rate 0.82 - 1.34 % 0.39 - 0.53 % Expected annual dividend yield 0.00 % 0.00 % Expected stock price volatility 85.4 - 89.3 % 89.0 - 90.7 % Expected term (in years) 5.0 - 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, 2021 2020 Research and development $ 1,237 $ 1,239 General and administrative 1,580 1,575 Total stock-based compensation expense $ 2,817 $ 2,814

Net Income (Loss) per Share (Ta

Net Income (Loss) per Share (Tables)	12 Months Ended
	Dec. 31, 2021
Earnings Per Share [Abstract]
Schedule of Reconciliation of Weighted Average Shares of Common Stock	The following is a reconciliation of weighted-average shares of common stock outstanding used in calculating basic net income per share to weighted-average shares of common stock outstanding used in calculating diluted net loss per share: Year Ended December 31, 2021 2020 Weighted-average shares of common stock outstanding, basic 21,733,960 476,700 Add: Effect of dilutive securities Series B Preferred Stock — 365,541 Series C Preferred Stock — 953,619 Total 21,733,960 1,795,860
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, 2021 2020 Series A Preferred Stock — 3,719,410 Series B Preferred Stock — — Series C Preferred Stock — — Series D Preferred Stock — 5,988,773 Outstanding stock options 3,037,463 2,686,120 Unvested restricted stock 12,537 52,741 3,050,000 12,447,044

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Schedule of Loss before Provision for Income Tax	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. For financial reporting purposes, loss before provision for income taxes, includes the following components (in thousands): Year Ended December 31, 2021 2020 Domestic $ ( 50,825 ) $ ( 37,501 ) Foreign 799 ( 1,836 ) Loss before income taxes $ ( 50,026 ) $ ( 39,337 )
Components of Provision (Benefit) for Income Taxes	The provision (benefit) for income taxes consists of the following (in thousands): Year Ended December 31, 2021 2020 Current: Federal $ — $ — State — — Foreign 1,797 — Total Current 1,797 — Deferred: Federal — — State — — Foreign — — Total Deferred — — Loss before income taxes $ 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, 2021 2020 Expected income tax benefit at the federal statutory rate 21.0 % 21.0 % State taxes 5.8 5.8 Foreign taxes ( 0.5 ) ( 1.0 ) Change in valuation allowance ( 27.2 ) ( 25.7 ) Research and development tax credits 0.7 0.9 Foreign rate differential ( 0.1 ) 0.4 Stock compensation ( 0.5 ) ( 0.8 ) Uncertain Tax Position ( 2.9 ) — Permanent differences 0.1 ( 0.6 ) Effective income tax rate ( 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, 2021 2020 Deferred tax assets: Federal, state and foreign net operating loss carryforwards $ 53,075 $ 41,379 Research and development and other credits 1,840 1,333 Deferred rent and lease incentive obligation 1,321 1,506 Accrued expenses and other 1,551 1,063 Total gross deferred tax assets 57,787 45,281 Valuation allowance ( 57,013 ) ( 44,305 ) Total deferred tax assets $ 774 $ 976 Deferred tax liabilities: Depreciation of fixed assets ( 774 ) ( 976 ) Total deferred tax liabilities $ ( 774 ) $ ( 976 ) 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, 2021 2020 Valuation allowance at beginning of the year $ 44,305 $ 34,203 Increases recorded to income tax provision 12,708 10,102 Valuation allowance at end of year $ 57,013 $ 44,305
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, 2021 2020 Unrecognized tax benefits at the beginning of the period $ — $ — Increases for current tax positions 2,084 — Increases for previous tax positions — — Decreases for previous tax positions — — Unrecognized tax benefits at the end of the period $ 2,084 $ —

Nature of the Business - Additi

Nature of the Business - Additional Information (Details) $ / shares in Units, $ in Millions	Feb. 24, 2021USD ($)shares	Feb. 17, 2021$ / sharesshares	Feb. 05, 2021	Oct. 30, 2020	Dec. 31, 2021USD ($)shares
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
Aggregate proceeds from initial public offering | $	$ 125
Cash, cash equivalents and available-for-sale securities | $					$ 162.3
Initial Public Offering
Nature Of Business Disclosure [Line Items]
Number of shares issued and sold		7,062,000
Stock issued, price per share | $ / shares		$ 18
Underwriters
Nature Of Business Disclosure [Line Items]
Number of shares issued and sold	600,000
Common Stock
Nature Of Business Disclosure [Line Items]
Reverse stock-split, description					On October 30, 2020, the Company’s board of directors approved a 1-for-10 reverse stock split of the Company’s common stock. 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	0.1
Number of shares issued and sold					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, 2021	Dec. 31, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Cash and cash equivalents	$ 36,455	$ 27,742
Restricted cash	1,128	1,476
Total cash, cash equivalents and restricted cash as shown on the statement of cash flows	$ 37,583	$ 29,218	$ 20,039

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2021	Dec. 31, 2020
Summary of Significant Accounting Policies [Line Items]
Off-balance sheet arrangements	$ 0	$ 0	$ 0
Allowance of accounts receivable	0	0	0
Unrealized loss on available-for-sale securities		(131,000)	(11,000)
Deferred offering costs	0	0
Employee retention credit	900,000
Research and development tax incentives	600,000	600,000	500,000
Maximum
Summary of Significant Accounting Policies [Line Items]
FDIC insured amount	$ 250,000	$ 250,000
Unrealized loss on available-for-sale securities			(100,000)
Initial Public Offering
Summary of Significant Accounting Policies [Line Items]
Deferred offering costs			$ 1,600,000

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Schedule of Property and Equipment Estimated Useful Lives (Details)	12 Months Ended
	Dec. 31, 2021
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

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Financial Assets Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Available-for-sale securities	$ 112,292	$ 26,568
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	31,726	24,462
Available-for-sale securities	112,292	26,568
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	31,726	7,962
Fair Value, Measurements | Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Total cash equivalents		16,500
Available-for-sale securities	112,292	26,568
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	31,726	7,962
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	31,726	7,962
Corporate debt securities | Fair Value, Measurements
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Total cash equivalents		4,001
Available-for-sale securities	33,806	1,286
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]
Total cash equivalents		4,001
Available-for-sale securities	33,806	1,286
Commercial paper | Fair Value, Measurements
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Total cash equivalents		12,499
Available-for-sale securities	1,999	19,481
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]
Total cash equivalents		12,499
Available-for-sale securities	1,999	19,481
Agency bonds | Fair Value, Measurements
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Available-for-sale securities	15,114
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	15,114
US Treasury securities | Fair Value, Measurements
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Available-for-sale securities	61,373	3,027
Available-for-sale securities, long-term	13,547
US 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	61,373	3,027
Available-for-sale securities, long-term	$ 13,547
Certificates of deposit | Fair Value, Measurements
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Available-for-sale securities		2,774
Certificates of deposit | 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		$ 2,774

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Fair Value Disclosures [Abstract]
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

Available-for-Sale Securities -

Available-for-Sale Securities - Summary of Available-for-Sale Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current
Available-for-sale Securities [Line Items]
Amortized Cost	$ 112,386	$ 26,569
Gross Unrealized Gain		1
Gross Unrealized Loss	(94)	(2)
Fair Value	112,292	26,568
Noncurrent
Available-for-sale Securities [Line Items]
Amortized Cost	13,585
Gross Unrealized Loss	(38)
Fair Value	13,547
US Treasury securities | Current
Available-for-sale Securities [Line Items]
Amortized Cost	61,450	3,027
Gross Unrealized Loss	(77)
Fair Value	61,373	3,027
US Treasury securities | Noncurrent
Available-for-sale Securities [Line Items]
Amortized Cost	13,585
Gross Unrealized Loss	(38)
Fair Value	13,547
Corporate debt securities | Current
Available-for-sale Securities [Line Items]
Amortized Cost	33,814	1,286
Gross Unrealized Loss	(8)
Fair Value	33,806	1,286
Agency bonds | Current
Available-for-sale Securities [Line Items]
Amortized Cost	15,123
Gross Unrealized Loss	(9)
Fair Value	15,114
Commercial paper | Current
Available-for-sale Securities [Line Items]
Amortized Cost	1,999	19,481
Gross Unrealized Gain		1
Gross Unrealized Loss		(1)
Fair Value	$ 1,999	19,481
Certificates of deposit | Current
Available-for-sale Securities [Line Items]
Amortized Cost		2,775
Gross Unrealized Loss		(1)
Fair Value		$ 2,774

Available-for-Sale Securities_2

Available-for-Sale Securities - Additional Information (Details)	12 Months Ended
	Dec. 31, 2021USD ($)Investment	Dec. 31, 2020USD ($)Investment
Investments, Debt and Equity Securities [Abstract]
Number of investments in available-for-sale securities in unrealized loss position | Investment	43	8
Available-for-sale securities, unrealized loss position	$ 120,300,000	$ 17,100,000
Other-than-temporary impairments related to available-for-sale securities in an unrealized loss position	$ 0	0
Investments matured	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, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 11,594	$ 11,125
Accumulated depreciation	(5,983)	(4,788)
Property and equipment, net	5,611	6,337
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	3,339	2,870
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

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jul. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Capital lease liability		$ 0.5
Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration]		Liabilities
Remaining portion of capital lease liability		$ 0.2
Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]		Accrued Liabilities And Other Current Liabilities
Depreciation expense		$ 1.4	$ 1.6
Finance lease, carrying value		$ 0.2
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]		Other Assets, Noncurrent
Finance lease, accumulated amortization		$ 0.3
Laboratory equipment
Property, Plant and Equipment [Line Items]
One-time cash payment	$ 0.5
Payments to acquire equipment on lease	$ 0.2
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, 2021	Dec. 31, 2020
Payables and Accruals [Abstract]
Accrued research and development expense	$ 3,152	$ 680
Accrued payroll and related expenses	2,932	2,381
Accrued other and other current liabilities	1,035	557
Equipment financing, current	213	193
Accrued professional fees	380	1,854
Accrued Expenses and Other Current Liabilities	$ 7,712	$ 5,665

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($)	1 Months Ended						12 Months Ended
	May 31, 2021	Oct. 31, 2020	Jan. 31, 2020	Sep. 30, 2019	Aug. 31, 2019	Jul. 31, 2016	Dec. 31, 2021	Dec. 31, 2020	Oct. 31, 2019
Other Commitments [Line Items]
Base rent payment						$ 2,100,000
Percentage of annual increase in operating lease						3.00%
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	$ 800,000
Tenant improvement allowance by landlord							5,300,000
Tenant improvements							7,100,000	7,100,000
Rent expenses							1,200,000	1,600,000
Cash refund related to research and development activities received							1,200,000	1,200,000
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
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
The University of Missouri License
Other Commitments [Line Items]
Upfront fee paid					$ 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				$ 1,200,000
Lease expiration date				2027-01
Lease secured by letter of credit							$ 500,000	$ 600,000
Sublease Agreement | Office and Laboratory Space
Other Commitments [Line Items]
Base rent payment	$ 1,700,000
Lease term commencement month and year			2020-03
Lease term of contract			24 months
Sublease Income			$ 1,100,000
Lease term option to extend			true
Lease term option to extend description			sublease provides the sublessee one option to extend up to one year
Lease renewal term			1 year
Percentage of sublease annual base rent increase			3.00%
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, 2021USD ($)
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2022	$ 3,616
2023	3,705
2024	3,795
2025	3,888
2026	3,984
Thereafter	1,357
Total	$ 20,345

Restructuring - Additional Info

Restructuring - Additional Information (Details)	1 Months Ended		3 Months Ended				12 Months Ended
	Jan. 31, 2021USD ($)	Nov. 30, 2020USD ($)	Dec. 31, 2020USD ($)	Sep. 30, 2020USD ($)	Jun. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2021USD ($)	Dec. 31, 2020USD ($)	May 31, 2020Employee
Restructuring Cost And Reserve [Line Items]
Termination of full-time employees | Employee									45
Restructuring charges					$ 554,000	$ 2,919,000	$ 0	$ 3,473,000
Retention cost					400,000	1,600,000
Termination benefits paid			$ (186,000)	$ (863,000)	$ (920,000)	(1,496,000)
First Payment Upon Execution of Retention Agreement
Restructuring Cost And Reserve [Line Items]
Retention cost						$ 700,000
Second Payment Upon Closing of Series D Financing
Restructuring Cost And Reserve [Line Items]
Retention cost		$ 400,000
Third Payment Upon Execution of Retention Agreement
Restructuring Cost And Reserve [Line Items]
Retention cost	$ 500,000

Restructuring - Summary of Rest

Restructuring - Summary of Restructuring Activity (Details) - USD ($)	3 Months Ended				12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Restructuring and Related Activities [Abstract]
Balance	$ 194,000	$ 1,057,000	$ 1,423,000		$ 8,000
Restructuring costs incurred			554,000	$ 2,919,000	$ 0	$ 3,473,000
Termination benefits paid	(186,000)	(863,000)	(920,000)	(1,496,000)
Balance	$ 8,000	$ 194,000	$ 1,057,000	$ 1,423,000		$ 8,000

Restructuring - Summary of Re_2

Restructuring - Summary of Restructuring Expense (Details) - USD ($)	3 Months Ended		12 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Restructuring Cost And Reserve [Line Items]
Restructuring charges	$ 554,000	$ 2,919,000	$ 0	$ 3,473,000
Research and Development
Restructuring Cost And Reserve [Line Items]
Restructuring charges				2,723,000
General and Administrative
Restructuring Cost And Reserve [Line Items]
Restructuring charges				$ 750,000

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details)	Dec. 31, 2021Vote$ / sharesshares	Dec. 31, 2020$ / sharesshares
Equity [Abstract]
Common stock, Shares authorized | shares	200,000,000	115,000,000
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	0
Common shares, votes per share | Vote	1

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Common Stock Reserved for Future Issuance (Details) - shares	Dec. 31, 2021	Dec. 31, 2020
Class Of Stock [Line Items]
Common stock reserved for future issuance	4,825,093	17,144,347
2015 Stock Incentive Plan
Class Of Stock [Line Items]
Common stock reserved for future issuance		790,596
Shares reserved for exercise of outstanding stock options	2,540,963	2,686,120
2021 Stock Incentive Plan
Class Of Stock [Line Items]
Common stock reserved for future issuance	1,221,593
Shares reserved for exercise of outstanding stock options	496,500
2021 Employee Stock Purchase Plan
Class Of Stock [Line Items]
Common stock reserved for future issuance	566,037
Series A convertible preferred stock
Class Of Stock [Line Items]
Common stock reserved for future issuance		3,719,410
Series B convertible preferred stock
Class Of Stock [Line Items]
Common stock reserved for future issuance		989,299
Series C convertible preferred stock
Class Of Stock [Line Items]
Common stock reserved for future issuance		2,970,149
Series D convertible preferred stock
Class Of Stock [Line Items]
Common stock reserved for future issuance		5,988,773

Convertible Preferred Stock - A

Convertible Preferred Stock - Additional Information (Details) - USD ($)	1 Months Ended		12 Months Ended
	Feb. 28, 2021	Nov. 30, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Feb. 17, 2021	Nov. 02, 2020	Oct. 31, 2020
Temporary Equity [Line Items]
Preferred Stock Issued				139,527,869
Net proceeds from issuance of convertible preferred stock			$ 27,400,000	$ 54,800,000
Convertible preferred stock, Shares authorized				155,398,078
Preferred stock, shares issued			0	0
Preferred stock, Shares authorized			5,000,000	0
Preferred stock, Par value			$ 0.001	$ 0.001
Convertible preferred stock, liquidation preference percentage								51.776%
Gain on extinguishment of convertible preferred stock				$ 103,500,000
Preferred stock voting rights			Prior to the IPO, the holders of the Convertible Preferred Stock voted as a single class and had one vote per share on general corporate matters. Significant transactions, including the consummation of the sale of the Company or an IPO, acquiring a business or the sale of company assets, redeeming or repurchasing shares, incurring indebtedness, issuing shares or any other series of capital units, declaring or paying dividends, commencing bankruptcy or insolvency actions, amending the research and development plan, or making any material change to the nature of the Company’s business, was required to be approved by at least 60.0% of existing the preferred stockholders, voting as a single class. The holders of Series D Preferred Stock were entitled to elect up to three directors, and the holders of Convertible Preferred Stock, voting as a single class, had the right to elect up to three directors. Holders of common stock and Convertible Preferred stock voting as a single class were entitled to elect the balance of the total number of directors of the Company.
Minimum voting percentage approved by existing preferred stockholders			60.00%
Dividends accrued				12,200,000
Dividends declared or paid			$ 0	$ 0
Preferred Stock Outstanding				139,527,869
Temporary equity voting percentage				60.00%
Deemed liquidation event voting rights description			the holders of at least 60.0% of the then outstanding shares of Convertible Preferred Stock on an as-converted to common stock basis and (ii) the holders of a majority of the then outstanding Series D Preferred Stock on an as-converted to common stock basis, elected otherwise. After all preferential payments, the common stockholders were entitled to share in the remaining assets of the Company on a pro rata basis.
Rights and preferences specific to the series B convertible preferred shares description			The holder of Series B Preferred Stock had a right of first offer with respect to the Company’s sale of new securities, including the common stock offered in an IPO, allowing the holder of Series B Preferred Stock to purchase up to the lesser of (1) one-third of the aggregate number of new securities then being offered and (2) such number of new securities such that, immediately following the closing of such sale, the holder of Series B Preferred Stock would own 25% of the Company’s outstanding capital stock on a fully diluted basis immediately following the closing of such sale. The right of first offer granted to the holder of Series B Preferred Stock preceded the first offer rights of holders of Series A Preferred Stock and Series C Preferred Stock. Additionally, the holder had the right to purchase, in a side-by-side private placement at the time of a qualified IPO, such number of new shares of Common Stock such that, immediately following the closing of such IPO, the holder would own 30% of the Company’s outstanding capital stock on a fully diluted basis.
Minimum
Temporary Equity [Line Items]
Gross proceeds from issuance of initial public offering				$ 75,000,000
Initial Public Offering
Temporary Equity [Line Items]
Dividends accrued			$ 2,300,000			$ 0
Initial Public Offering | Minimum
Temporary Equity [Line Items]
Conversion price per share				$ 13.7259
Series A convertible preferred stock
Temporary Equity [Line Items]
Preferred Stock Issued			0	57,758,734	57,758,734
Convertible preferred stock, Par value			$ 0.001	$ 0.001	$ 0.001
Net proceeds from issuance of convertible preferred stock					$ 57,700,000
Convertible preferred stock, Shares authorized			0	57,758,734
Dividends accrued rate per share			$ 0.08
Preferred Stock Outstanding			0	57,758,734	57,758,734
Conversion price per share			$ 1	$ 15.529
Temporary equity, liquidation preference description			(i) the sum of $0.51776 per share, plus the respective Pre-Series D Cumulative Dividends accrued but unpaid, whether or not declared, plus the respective Post-Series D Cumulative Dividends accrued but unpaid, whether or not declared, together with any other dividends declared but unpaid or (ii) any such amount per share as would have been payable had all shares of Series A Preferred Stock been converted into common stock immediately prior to such liquidation event.
Temporary equity, liquidation preference per share			$ 0.51776
Series B convertible preferred stock
Temporary Equity [Line Items]
Preferred Stock Issued			0	12,500,000	12,500,000
Convertible preferred stock, Par value			$ 0.001	$ 0.001	$ 0.001
Net proceeds from issuance of convertible preferred stock					$ 25,000,000
Convertible preferred stock, Shares authorized			0	12,500,000
Dividends accrued rate per share			$ 0.16
Preferred Stock Outstanding			0	12,500,000	12,500,000
Conversion price per share			$ 2	$ 25.27
Temporary equity, liquidation preference description			the sum of $1.03552 per share, plus the respective Pre-Series D Cumulative Dividends accrued but unpaid, whether or not declared, plus the respective Post-Series D Cumulative Dividends accrued but unpaid, whether or not declared, together with any other dividends declared but unpaid or (ii) any such amount per share as would have been payable had all shares of Series B Preferred Stock and Series C Preferred Stock been converted into common stock immediately prior to such liquidation event.
Temporary equity, liquidation preference per share			$ 1.03552
Percentage of outstanding capital stock on fully diluted basis			25.00%
Series B convertible preferred stock | Initial Public Offering
Temporary Equity [Line Items]
Percentage of outstanding capital stock on fully diluted basis			30.00%
Series C convertible preferred stock
Temporary Equity [Line Items]
Preferred Stock Issued			0	37,528,581	27,528,581
Convertible preferred stock, Par value			$ 0.001	$ 0.001	$ 0.001
Net proceeds from issuance of convertible preferred stock					$ 55,000,000
Convertible preferred stock, Shares authorized			0	37,528,581
Issuance of convertible preferred stock, Shares				10,000,000
Preferred stock, shares issued								10,000,000
Dividends accrued rate per share			$ 0.16
Preferred Stock Outstanding			0	37,528,581	27,528,581
Conversion price per share			$ 2	$ 25.27
Temporary equity, liquidation preference description			the sum of $1.03552 per share, plus the respective Pre-Series D Cumulative Dividends accrued but unpaid, whether or not declared, plus the respective Post-Series D Cumulative Dividends accrued but unpaid, whether or not declared, together with any other dividends declared but unpaid or (ii) any such amount per share as would have been payable had all shares of Series B Preferred Stock and Series C Preferred Stock been converted into common stock immediately prior to such liquidation event.
Temporary equity, liquidation preference per share			$ 1.03552
Series D convertible preferred stock
Temporary Equity [Line Items]
Preferred Stock Issued		31,740,554	0	31,740,554
Convertible preferred stock, Par value			$ 0.001	$ 0.001				$ 0.001
Net proceeds from issuance of convertible preferred stock	$ 27,400,000	$ 54,500,000
Convertible preferred stock, Shares authorized			0	47,610,763				47,610,763
Issuance of convertible preferred stock, Shares	15,870,209		15,870,209
Price per share, convertible preferred stock		$ 1.7265
Dividends accrued rate per share			$ 0.13812
Preferred Stock Outstanding			0	31,740,554
Conversion price per share			$ 1.7265	$ 9.15
Temporary equity, liquidation preference description			$1.7265 per share plus any dividends accrued but unpaid, together with any other dividends declared but unpaid or (ii) any such amount per share as would have been payable had all shares of Series D Preferred Stock been converted into common stock immediately prior to such liquidation event.
Temporary equity, liquidation preference per share			$ 1.7265
Series D convertible preferred stock | Entity Obligation to Sell and Obligation to Purchase Additional Shares by Investor [Member] | Upon Second Tranche Closing [Member]
Temporary Equity [Line Items]
Net proceeds from issuance of convertible preferred stock		$ 27,400,000
Issuance of convertible preferred stock, Shares		15,870,209
Price per share, convertible preferred stock		$ 1.7265
Series A, Series B and Series C convertible preferred stock
Temporary Equity [Line Items]
Dividend accrued percentage							51.776%
Convertible Preferred Stock | Initial Public Offering
Temporary Equity [Line Items]
Preferred Stock Issued						0
Preferred Stock Outstanding			0

Convertible Preferred Stock - S

Convertible Preferred Stock - Schedule of Convertible Preferred Stock (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Nov. 30, 2020	Oct. 31, 2020	Dec. 31, 2019
Temporary Equity [Line Items]
Preferred Stock Authorized		155,398,078
Preferred Stock Issued		139,527,869
Preferred Stock Outstanding		139,527,869
Carrying Value		$ 93,091
Liquidation Preference		$ 157,584
Common Stock Issuable Upon Conversion		13,667,631
Series A convertible preferred stock
Temporary Equity [Line Items]
Preferred Stock Authorized	0	57,758,734
Preferred Stock Issued	0	57,758,734			57,758,734
Preferred Stock Outstanding	0	57,758,734			57,758,734
Carrying Value		$ 16,176			$ 57,682
Liquidation Preference		$ 40,284
Common Stock Issuable Upon Conversion		3,719,410
Series B convertible preferred stock
Temporary Equity [Line Items]
Preferred Stock Authorized	0	12,500,000
Preferred Stock Issued	0	12,500,000			12,500,000
Preferred Stock Outstanding	0	12,500,000			12,500,000
Carrying Value		$ 5,700			$ 24,957
Liquidation Preference		$ 16,334
Common Stock Issuable Upon Conversion		989,299
Series C convertible preferred stock
Temporary Equity [Line Items]
Preferred Stock Authorized	0	37,528,581
Preferred Stock Issued	0	37,528,581			27,528,581
Preferred Stock Outstanding	0	37,528,581			27,528,581
Carrying Value		$ 16,759			$ 55,005
Liquidation Preference		$ 45,457
Common Stock Issuable Upon Conversion		2,970,149
Series D convertible preferred stock
Temporary Equity [Line Items]
Preferred Stock Authorized	0	47,610,763		47,610,763
Preferred Stock Issued	0	31,740,554	31,740,554
Preferred Stock Outstanding	0	31,740,554
Carrying Value		$ 54,456
Liquidation Preference		$ 55,509
Common Stock Issuable Upon Conversion		5,988,773

Convertible Preferred Stock -_2

Convertible Preferred Stock - Schedule of Cumulative Dividends on Convertible Preferred Stock (Details) $ in Thousands	Dec. 31, 2020USD ($)
Temporary Equity [Line Items]
Cumulative dividends	$ 21,129
Series A convertible preferred stock
Temporary Equity [Line Items]
Cumulative dividends	10,399
Series B convertible preferred stock
Temporary Equity [Line Items]
Cumulative dividends	3,398
Series C convertible preferred stock
Temporary Equity [Line Items]
Cumulative dividends	6,623
Series D convertible preferred stock
Temporary Equity [Line Items]
Cumulative dividends	$ 709

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	4,825,093	17,144,347
Issuance of common stock upon exercise of stock options	$ 319,000	$ 70,000
Stock-based compensation expense, income tax benefits	0	0
Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Aggregate fair value of awards vested	600,000	1,400,000
Unrecognized compensation cost related to unvested stock	$ 300,000
Weighted-average period of unvested stock	6 months
Issuance of common stock upon exercise of stock options	$ 0	$ 0
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares reserved for outstanding awards granted	681,200
Unrecognized compensation cost related to unvested stock	$ 7,200,000
Weighted-average period of unvested stock	2 years 11 months 1 day
Weighted average grant-date fair value of share options granted	$ 6.99	$ 3.19
Intrinsic value of options exercised	$ 200,000	$ 100,000
2015 Stock Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock, authorized for issuance		3,930,701
Common stock reserved for future issuance		790,596
2015 Stock Incentive Plan | Initial Public Offering | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	3,529,250
2021 Stock Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	1,221,593
Vesting period	4 years
Vesting description	generally vest over a 4-year period with vesting of awards subject to the recipient’s continued employment or service
2021 Stock Incentive Plan | Initial Public Offering
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	849,056
Number of shares reserved for outstanding awards granted	496,500
Number of shares remained available for issuance	1,221,593
Stock option plan expiration period	10 years
2021 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance	566,037
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
Number of shares remained available for issuance	566,037
Number of shares issued	0

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Restricted Stock Activity (Details) - Restricted Stock	12 Months Ended
	Dec. 31, 2021$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Stock Outstanding, Beginning Balance | shares	52,741
Number of Stock, Vested | shares	(34,759)
Number of Stock, Repurchased | shares	(777)
Number of Stock, Canceled/Forfeited | shares	(4,668)
Number of Stock Outstanding, Ending Balance | shares	12,537
Weighted Average Grant Date Fair Value, Beginning Balance | $ / shares	$ 19.10
Weighted Average Grant Date Fair Value, Vested | $ / shares	17.21
Weighted Average Grant Date Fair Value, Repurchased | $ / shares	0.53
Weighted Average Grant Date Fair Value, Canceled/Forfeited | $ / shares	20.96
Weighted Average Grant Date Fair Value, Ending Balance | $ / shares	$ 24.79

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Stock Option Activity (Details) - Stock Options - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Stock Options, Outstanding as of December 31, 2020	2,686,120
Number of Stock Options, Granted	681,200
Number of Stock Options, Exercised	(72,161)
Number of Stock Options, Cancelled/forfeited	(257,696)
Number of Stock Options, Outstanding as of December 31, 2021	3,037,463	2,686,120
Number of Stock Options, Exercisable as of September 30, 2021	1,160,914
Number of Stock Options, Vested and expected to vest as of December 31, 2021	3,037,463
Weighted Average Exercise Price, Outstanding as of December 31, 2020	$ 4.53
Weighted Average Exercise Price, Granted	9.25
Weighted Average Exercise Price, Exercised	4.40
Weighted Average Exercise Price, Cancelled/forfeited	7.50
Weighted Average Exercise Price, Outstanding as of December 31, 2021	5.34	$ 4.53
Weighted Average Exercise Price, Exercisable as of September 30, 2021	4.96
Weighted Average Exercise Price, Vested and expected to vest as of December 31, 2021	$ 5.34
Weighted Average Remaining Contractual Term, Outstanding	8 years 10 months 24 days	9 years 10 months 24 days
Weighted Average Remaining Contractual Term, Exercisable as of September 30, 2021	8 years 8 months 12 days
Weighted Average Remaining Contractual Term, Vested and expected to vest as of December 31, 2021	8 years 10 months 24 days
Aggregate Intrinsic Value, Outstanding	$ 629	$ 3,781
Aggregate Intrinsic Value, Exercisable as of September 30, 2021	271
Aggregate Intrinsic Value, Vested and expected to vest as of December 31, 2021	$ 629

Stock-Based Compensation - Su_3

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, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate, Minimum	0.82%	0.39%
Risk-free interest rate, Maximum	1.34%	0.53%
Expected annual dividend yield	0.00%	0.00%
Expected stock price volatility, Minimum	85.40%	89.00%
Expected stock price volatility, Maximum	89.30%	90.70%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)	5 years	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, 2021	Dec. 31, 2020
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 2,817	$ 2,814
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	1,237	1,239
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 1,580	$ 1,575

Net Income (Loss) Per Share - S

Net Income (Loss) Per Share - Schedule of Reconciliation of Weighted Average Shares of Common Stock (Details) - shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted-average shares of common stock outstanding, basic	21,733,960	476,700
Weighted Average Number of Shares Outstanding, Basic and Diluted, Total	21,733,960	1,795,860
Series B Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Effect of dilutive securities		365,541
Series C Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Effect of dilutive securities		953,619

Net Income (Loss) Per Share - A

Net Income (Loss) Per Share - Additional Information (Details) - shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average shares of common stock outstanding, basic and diluted	21,733,960	1,795,860

Net Income (Loss) Per Share -_2

Net Income (Loss) Per Share - Schedule of Anti-Dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share, amount	3,050,000	12,447,044
Series A Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share, amount	0	3,719,410
Series B Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share, amount	0	0
Series C Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share, amount	0	0
Series D Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of earnings per share, amount	0	5,988,773
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	3,037,463	2,686,120
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	12,537	52,741

License and Collaboration Agr_2

License and Collaboration Agreement with Regeneron - Additional Information (Details) - USD ($)	1 Months Ended				3 Months Ended	12 Months Ended
	Nov. 30, 2022	Nov. 30, 2020	Oct. 31, 2020	Nov. 30, 2017	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
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
Preferred stock, price per share						$ 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
Ongoing research plan			$ 300,000				$ 300,000
CDMO Initiation Fee			500,000
Milestone associated payment		$ 4,400,000	500,000
Upfront payment						25,000,000
Milestone payment received						5,500,000
Unbilled receivable related to extension fee						10,000,000
Reduction in aggregate potential milestone payments			15,000,000
Transaction price							35,800,000
Received regeneron agreement amount							25,000,000
Contra-research and development expense						11,000,000	2,000,000
Cumulative catch-up amount						500,000	4,800,000
Deferred collaboration liability, current						8,118,000	10,968,000
Deferred collaboration liability, long term						16,431,000	4,177,000
Unbilled accounts receivable due from related party						11,400,000	1,200,000
Expected costs reimbursement from regeneron for costs incurred						$ 1,400,000
Scenario Forecast
License And Collaboration Agreement With Regeneron [Line Items]
Extension fee					$ 10,000,000
Obligated to pay	$ 10,000,000				$ 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
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
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, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Maximum annual contribution per employee	4.00%
Maximum contributions made by employer	$ 300,000	$ 0
Minimum
Defined Benefit Plan Disclosure [Line Items]
Percentage of employer matching contribution	50.00%
Percentage of employer matching contribution gross pay	2.00%
Maximum
Defined Benefit Plan Disclosure [Line Items]
Percentage of employer matching contribution	100.00%
Percentage of employer matching contribution gross pay	3.00%

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Operating Loss Carryforwards [Line Items]
Income tax expense (benefit)	$ 1,797,000	$ 0
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	$ 2,084,000
Unrecognized tax benefits that would affect income tax expense before consideration of valuation allowance	1,200,000
Unrecognized tax benefits deferred tax asset previously offset by a full valuation allowance	900,000
Accrued penalties and provisions for interest	$ 400,000	0
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	50.00%
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	$ 196,300,000	148,700,000
Net operating loss carryforwards with definite life	41,700,000
Net operating loss carryforwards with indefinite life	$ 154,600,000
Operating loss carryforwards, expiration period	2033
Federal | Research and Development Tax Credit Carryforwards
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	$ 1,200,000	$ 800,000
Tax credit carryforwards, expiration period	2033	2033
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 187,900,000	$ 146,000,000
Operating loss carryforwards, expiration period	2035	2035
State | Research and Development Tax Credit Carryforwards
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	$ 800,000	$ 500,000
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, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Domestic	$ (50,825)	$ (37,501)
Foreign	799	(1,836)
Net loss before provision for income taxes	$ (50,026)	$ (39,337)

Income Taxes - Components of Pr

Income Taxes - Components of Provision (Benefit) for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Current:
Foreign	$ 1,797
Total Current	1,797
Loss before income taxes	$ 1,797	$ 0

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, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Expected income tax benefit at the federal statutory rate	21.00%	21.00%
State taxes	5.80%	5.80%
Foreign taxes	(0.50%)	(1.00%)
Change in valuation allowance	(27.20%)	(25.70%)
Research and development tax credits	0.70%	0.90%
Foreign rate differential	(0.10%)	0.40%
Stock compensation	(0.50%)	(0.80%)
Uncertain Tax Position	(2.90%)
Permanent differences	0.10%	(0.60%)
Effective income tax rate	(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, 2021	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Federal, state and foreign net operating loss carryforwards	$ 53,075	$ 41,379
Research and development and other credits	1,840	1,333
Deferred rent and lease incentive obligation	1,321	1,506
Accrued expenses and other	1,551	1,063
Total gross deferred tax assets	57,787	45,281
Valuation allowance	(57,013)	(44,305)	$ (34,203)
Total deferred tax assets	774	976
Deferred tax liabilities:
Depreciation of fixed assets	(774)	(976)
Total deferred tax liabilities	$ (774)	$ (976)

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, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Valuation allowance at beginning of the year	$ 44,305	$ 34,203
Increases recorded to income tax provision	12,708	10,102
Valuation allowance at end of year	$ 57,013	$ 44,305

Income Taxes - Summary of rec_2

Income Taxes - Summary of reconciliation of the gross unrecognized tax benefits (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021USD ($)
Income Tax Disclosure [Abstract]
Increases for current tax positions	$ 2,084
Unrecognized Tax Benefits, Ending Balance	$ 2,084

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Oct. 31, 2020
Related Party Transaction [Line Items]
Shares held from Regeneron	0	0
Unbilled accounts receivable due from Regeneron	$ 11.4	$ 1.2
Consulting services expenses	0.2	0.1
Contra-research and development expense	$ 11	$ 2
Series C Preferred Stock
Related Party Transaction [Line Items]
Shares held from Regeneron			10,000,000