Akouos (AKUS) 10-Q12 May 222021 Q3 Quarterly reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2022	Apr. 29, 2022
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Mar. 31, 2022
Current Fiscal Year End Date	--12-31
Entity File Number	001-39343
Entity Registrant Name	AKOUOS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	81-1716654
Entity Address, Address Line One	645 Summer Street, Suite 200
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02210
City Area Code	857
Local Phone Number	410-1818
Title of 12(b) Security	Common Stock, $0.0001 Par Value per Share
Trading Symbol	AKUS
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		34,626,156
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Entity Central Index Key	0001722271
Amendment Flag	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current Assets
Cash and cash equivalents	$ 54,382	$ 121,907
Marketable securities	154,716	110,545
Prepaid expenses and other current assets	2,353	3,711
Total current assets	211,451	236,163
Property and equipment, net	21,849	19,803
Operating lease rightofuse assets	20,167	20,341
Restricted cash	2,448	2,448
Other assets	43
Total assets	255,958	278,755
Current Liabilities
Accounts payable	1,331	1,280
Accrued expenses and other current liabilities	16,517	14,850
Operating lease liabilities	711	671
Total current liabilities	18,559	16,801
Operating lease liabilities, net of current portion	28,415	28,304
Total liabilities	46,974	45,105
Commitments and contingencies (See Note 11)
Stockholders' Equity
Common stock, $0.0001 par value: Authorized: 200,000,000 shares at March 31, 2022 and December 31, 2021. Issued and outstanding: 34,605,503 and 34,498,443 shares at March 31, 2022 and December 31, 2021, respectively.	3	3
Additional paidin capital	405,094	402,244
Accumulated other comprehensive loss	(735)	(202)
Accumulated deficit	(195,378)	(168,395)
Total stockholders' equity	208,984	233,650
Total liabilities and stockholders' equity	$ 255,958	$ 278,755

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2022	Dec. 31, 2021
CONDENSED CONSOLIDATED BALANCE SHEETS
Preferred stock, Par value	$ 0.0001	$ 0.0001
Preferred stock, Shares authorized	5,000,000	5,000,000
Preferred stock, Shares issued	0	0
Preferred stock, Shares outstanding	0	0
Common stock, Par value	$ 0.0001	$ 0.0001
Common stock, Shares authorized	200,000,000	200,000,000
Common stock, Shares issued	34,605,503	34,498,443
Common stock, Shares outstanding	34,605,503	34,498,443

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENT OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating expenses:
Research and development	$ 20,388	$ 11,258
General and administrative	6,646	4,890
Total operating expenses	27,034	16,148
Loss from operations	(27,034)	(16,148)
Other income (expense):
Interest income	257	509
Other expense, net	(206)	(447)
Total other income, net	51	62
Net loss	$ (26,983)	$ (16,086)
Net loss per share attributable to common stockholders, basic	$ (0.78)	$ (0.47)
Net loss per share attributable to common stockholders, diluted	$ (0.78)	$ (0.47)
Weighted-average common shares outstanding, basic	34,528,992	34,284,419
Weighted-average common shares outstanding, diluted	34,528,992	34,284,419
Unrealized gain (loss) on marketable securities	$ (533)	$ 28
Total other comprehensive income (loss)	(533)	28
Total comprehensive loss	$ (27,516)	$ (16,058)

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Accumulated Deficit	Total
Balances at beginning of period at Dec. 31, 2020	$ 3	$ 392,322	$ 13	$ (81,724)	$ 310,614
Balances at beginning of period (in shares) at Dec. 31, 2020	34,383,719
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options		225			225
Issuance of common stock upon exercise of stock options (in shares)	62,197
Vesting of restricted common stock from early-exercised stock options		21			21
Stock-based compensation expense		2,000			2,000
Net loss				(16,086)	(16,086)
Unrealized gain (loss) on marketable securities			28		28
Balances at end of period at Mar. 31, 2021	$ 3	394,568	41	(97,810)	296,802
Balances at end of period (in shares) at Mar. 31, 2021	34,445,916
Balances at beginning of period at Dec. 31, 2021	$ 3	402,244	(202)	(168,395)	233,650
Balances at beginning of period (in shares) at Dec. 31, 2021	34,498,443
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options		220			220
Issuance of common stock upon exercise of stock options (in shares)	107,060
Vesting of restricted common stock from early-exercised stock options		4			4
Stock-based compensation expense		2,626			2,626
Net loss				(26,983)	(26,983)
Unrealized gain (loss) on marketable securities			(533)		(533)
Balances at end of period at Mar. 31, 2022	$ 3	$ 405,094	$ (735)	$ (195,378)	$ 208,984
Balances at end of period (in shares) at Mar. 31, 2022	34,605,503

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities:
Net loss	$ (26,983)	$ (16,086)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	748	544
Net amortization of premiums and accretion of discounts on marketable securities	188	442
Amortization of operating lease right-of-use assets	174	96
Stockbased compensation expense	2,626	2,000
Loss on disposal of property and equipment		5
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	1,358	(1,796)
Accounts payable	51	97
Other assets	(43)	10
Operating lease liabilities	151	(163)
Accrued expenses and other current liabilities	1,671	(1,071)
Net cash used in operating activities	(20,059)	(15,922)
Cash flows from investing activities:
Purchases of property and equipment	(2,794)	(4,107)
Purchases of marketable securities	(64,892)	(70,302)
Proceeds from sales or maturities of marketable securities	20,000	140,000
Net cash provided by (used in) investing activities	(47,686)	65,591
Cash flows from financing activities:
Payments of finance lease obligations		(63)
Proceeds from exercise of stock options	220	246
Net cash provided by financing activities	220	183
Net increase (decrease) in cash, cash equivalents and restricted cash	(67,525)	49,852
Cash, cash equivalents and restricted cash at beginning of period	124,355	70,249
Cash, cash equivalents and restricted cash at end of period	56,830	120,101
Supplemental cash flow information:
Cash paid for interest		1
Supplemental disclosure of noncash investing and financing information:
Vesting of common stock subject to repurchase	4	21
Remeasurement of operating lease right-of-use asset for lease modification		5,592
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	54,382	117,653
Restricted cash	2,448	2,448
Total cash, cash equivalents and restricted cash shown in the statement of cash flows	$ 56,830	$ 120,101

Nature of the Business and Basi

Nature of the Business and Basis of Presentation	3 Months Ended
Nature of the Business and Basis of Presentation	Mar. 31, 2022
Nature of the Business and Basis of Presentation
Nature of the Business and Basis of Presentation	1. Nature of the Business and Basis of Presentation Akouos, Inc., together with its consolidated subsidiary (the “Company” or “Akouos”), is a precision genetic medicine company dedicated to its mission of developing gene therapies with the potential to restore, improve, and preserve high-acuity physiologic hearing for individuals who live with disabling hearing loss worldwide. The Company was formed as a limited liability corporation under the laws of the Commonwealth of Massachusetts in March 2016 under the name Akouos, LLC and converted into a corporation under the laws of the State of Delaware in November 2016 under the name Akouos, Inc. The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry, including, but not limited to, development by competitors of new technological innovations, dependence on key personnel, protection of proprietary technology, compliance with government regulations, the impact of the COVID-19 pandemic, and the ability to secure additional capital to fund operations. Product candidates currently under development will require significant additional research and development efforts, including extensive preclinical and clinical testing and 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 development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales. On June 30, 2020, the Company completed its initial public offering of its common stock and issued and sold 14,375,000 shares of its common stock, at a public offering price of $17.00 per share, for gross proceeds of $244.4 million, or net proceeds of $223.8 million after deducting underwriting discounts, commissions, and offering expenses. In August 2021, the Company entered into a sales agreement (“the ATM Sales Agreement”) with Cowen and Company, LLC, (“Cowen”) to issue and sell, from time to time at prevailing market prices, shares of the Company’s common stock having aggregate gross proceeds of up to $100.0 million. Sales of common stock under the ATM Sales Agreement may be made by any method that is deemed an “at the market” offering as defined in Rule 415(a)(4) under the Securities Act of 1933, as amended. The Company agreed to pay Cowen a commission of 3.0% of the aggregate gross proceeds of any shares sold by Cowen under the ATM Sales Agreement. As of March 31, 2022, no sales have been made pursuant to the ATM Sales Agreement. The accompanying condensed consolidated financial statements have been prepared on the basis of continuity of operations, realization of assets, and the satisfaction of liabilities and commitments in the ordinary course of business. The Company has primarily funded its operations with proceeds from sales of convertible preferred stock and proceeds from the Company’s initial public offering of common stock. The Company has incurred losses and negative cash flows from operations since its inception. As of March 31, 2022, the Company had an accumulated deficit of $195.4 million. The Company expects that its operating losses and negative cash flows will continue for the foreseeable future. The Company expects that its existing cash, cash equivalents and marketable securities will be sufficient to fund its operating expenses and capital expenditure requirements for at least 12 months from the issuance date of the interim condensed consolidated financial statements. The Company expects to seek additional funding through public and private equity financings, debt financings, collaborations, licensing arrangements, and/or strategic alliances. The Company may not be able to obtain financing on acceptable terms, or at all, and the Company may not be able to enter into collaborations or other such arrangements. The terms of any financing may adversely affect the holdings or the rights of the Company’s stockholders. If the Company is unable to obtain funding, the Company could be forced to delay, reduce, or eliminate some or all of its research and development programs, product portfolio expansion, or commercialization efforts, which could adversely affect its business prospects. Although management continues to pursue these plans, there is no assurance that the Company will be successful in obtaining sufficient funding on terms acceptable to the Company to fund continuing operations, if at all. Impact of the COVID-19 Pandemic The COVID-19 pandemic has caused many governments to implement measures to slow the spread of the pandemic. The pandemic and government measures taken in response have had and will continue to have a significant impact, both direct and indirect, on businesses and commerce, as worker shortages have occurred, supply chains have been disrupted, and facilities and production have been suspended. The Company has experienced manufacturing delays at its third-party manufacturers, including delays related to the COVID-19 pandemic, and may experience additional delays in the future, including supply chain delays or shortages, which could further delay product development timelines. The future progression of the pandemic and its continued effects on the Company’s business and operations are uncertain. The COVID-19 pandemic may affect the Company’s ability to initiate and complete nonclinical studies, delay the initiation of its planned clinical trial or future clinical trials, disrupt regulatory activities, or have other adverse effects on its business and operations. In particular, the Company and its third-party manufacturers and contract research organizations may face additional disruptions that may affect the Company’s ability to initiate and complete nonclinical studies, obtain nonclinical and clinical supplies, and initiate clinical trial sites. The pandemic may cause significant disruptions in the financial markets, which could impact the Company’s ability to raise additional funds to support its operations. Moreover, the pandemic has significantly impacted economies worldwide, which could result in adverse effects on the Company’s business and operations. As described above, to date, the Company has experienced a business disruption at its third-party manufacturers, including delays related to the COVID-19 pandemic. The Company is continuing to monitor the impact of the COVID-19 pandemic on its business and financial statements. To date, the Company has not incurred impairment losses in the carrying values of its assets as a result of the pandemic and it is not aware of any specific related event or circumstance that would require it to revise its estimates reflected in these condensed consolidated financial statements. The extent to which the COVID-19 pandemic will continue to directly or indirectly impact the Company’s business, results of operations and financial condition, including planned and future clinical trials and research and development costs, will depend on future developments that are highly uncertain, including as a result of new information that may emerge concerning COVID-19, the actions taken to contain or treat it, and the duration and intensity of the related effects. Basis of Presentation The accompanying condensed consolidated financial statements reflect the operations of the Company and its wholly owned, domestic subsidiary. Intercompany balances and transactions have been eliminated in consolidation. The accompanying condensed consolidated financial statements have been prepared in conformity with generally accepted accounting principles 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 Update (“ASU”) of the Financial Accounting Standards Board (“FASB”). Use of Estimates The preparation of the Company’s consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenue and expenses during the reporting periods. Significant estimates and assumptions reflected in these condensed consolidated financial statements include, but are not limited to, the accrual of research and development expenses. The Company bases its estimates on historical experience, known trends, and other market specific or other relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates, as there are changes in circumstances, facts, and experience. Changes in estimates are recorded in the period in which they become known. Actual results may differ from those estimates or assumptions. Unaudited Interim Financial Information The accompanying condensed consolidated balance sheet as of March 31, 2022, the condensed consolidated statements of operations and comprehensive loss for the three months ended March 31, 2022 and 2021, the condensed consolidated statements of cash flows for the three months ended March 31, 2022 and 2021 and the condensed consolidated statements of stockholders’ equity for the three months ended March 31, 2022 and 2021 are unaudited. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited annual consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of March 31, 2022 and the results of its operations for the three months ended March 31, 2022 and 2021 and its cash flows for the three months ended March 31, 2022 and 2021. The financial data and other information disclosed in these notes related to the three months ended March 31, 2022 and 2021 are also unaudited. The results for the three months ended March 31, 2022 and 2021 are not necessarily indicative of results to be expected for the year ending December 31, 2022, any other interim periods, or any future year or period. The accompanying balance sheet as of December 31, 2021 has been derived from the Company’s audited financial statements for the year ended December 31, 2021. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to rules and regulations. However, the Company believes that the disclosures are adequate to make the information presented not misleading. The accompanying unaudited condensed consolidated financial statements and notes should be read in conjunction with the audited consolidated financial statements and related notes for the year ended December 31, 2021 included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2021 filed with the Securities and Exchange Commission (the “SEC”) on March 29, 2022 (the “Annual Report on Form 10-K”).

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
Summary of Significant Accounting Policies	Mar. 31, 2022
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Summary of Significant Accounting Policies The significant accounting policies and estimates used in the preparation of the accompanying consolidated financial statements are described in the Company’s audited consolidated financial statements included in the Annual Report on Form 10-K. There have been no material changes in the Company’s significant accounting policies during the three months ended March 31, 2022. Recently Adopted Accounting Pronouncements In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU ”) Income Taxes Recently Issued Accounting Pronouncements From time to time, new accounting pronouncements are issued by the FASB or other standard-setting bodies that the Company adopts as of the specified effective date. The Company qualifies as an “emerging growth company” as defined in the Jumpstart Our Business Startups Act of 2012 and has elected not to “opt out” of the extended transition period related to complying with new or revised accounting standards, which means that when a standard is issued or revised and it has different application dates for public and non-public companies, the Company can adopt the new or revised standard at the time non-public companies adopt the new or revised standard and can do so until such time that the Company either (i) irrevocably elects to “opt out” of such extended transition period or (ii) no longer qualifies as an emerging growth company. The Company may choose to early adopt any new or revised accounting standards whenever such early adoption is permitted for non-public companies. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments Codification Improvements to Topic 326, Financial Instruments—Credit Losses Financial Instruments—Credit Losses (Topic 326): Targeted Transition Relief

Fair Value Measurements

Fair Value Measurements	3 Months Ended
Fair Value Measurements	Mar. 31, 2022
Fair Value Measurements
Fair Value Measurements	3. Fair Value Measurements The following tables present the Company’s fair value hierarchy for its assets that are measured at fair value on a recurring basis and indicate the level within the fair value hierarchy of the valuation techniques the Company utilized to determine such fair value: Fair Value Measurements at March 31, 2022 Using: (in thousands) Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 55,895 $ — $ — $ 55,895 Restricted cash: Money market funds 2,448 — — 2,448 Marketable securities: U.S. Treasury notes — 154,716 — 154,716 $ 58,343 $ 154,716 $ — $ 213,059 Fair Value Measurements at December 31, 2021 Using: (in thousands) Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 121,018 $ — $ — $ 121,018 Restricted cash: Money market funds 2,448 — — 2,448 Marketable securities: U.S. Treasury notes — 110,545 — 110,545 $ 123,466 $ 110,545 $ — $ 234,011 U.S. government money market funds were valued by the Company based on quoted market prices, which represent a Level 1 measurement within the fair value hierarchy. As of March 31, 2022, the Company’s marketable securities consisted of U.S. Treasury notes, which were valued based on Level 2 inputs. In determining the fair value of its U.S. Treasury notes, the Company relied on quoted prices for similar securities in active markets or other inputs that are observable or can be corroborated by observable market data. During the three months ended March 31, 2022 and 2021, there were no transfers between Level 1, Level 2, and Level 3 of the fair value hierarchy.

Marketable Securities

Marketable Securities	3 Months Ended
Marketable Securities	Mar. 31, 2022
Marketable securities
Marketable securities	4. Marketable Securities As of March 31, 2022 and December 31, 2021, the fair value of available-for-sale marketable debt securities by type of security was as follows: March 31, 2022 Gross Gross Amortized Unrealized Unrealized Fair (in thousands) Cost Gain Loss Value Assets Marketable securities: U.S. Treasury notes $ 155,451 $ — $ (735) $ 154,716 $ 155,451 $ — $ (735) $ 154,716 December 31, 2021 Gross Gross Amortized Unrealized Unrealized Fair (in thousands) Cost Gain Loss Value Assets Marketable securities: U.S. Treasury notes $ 110,747 $ — $ (202) $ 110,545 $ 110,747 $ — $ (202) $ 110,545 At March 31, 2022 and December 31, 2021, all available-for-sale marketable securities had contractual maturities of less than two years.

Property and Equipment, Net

Property and Equipment, Net	3 Months Ended
Property and Equipment, Net	Mar. 31, 2022
Property and Equipment, Net
Property and Equipment, Net	5. Property and Equipment, Net Property and equipment, net consisted of the following: (in thousands) March 31, 2022 December 31, 2021 Laboratory equipment $ 8,226 $ 7,595 Furniture and fixtures 611 600 Leasehold improvements 15,871 15,871 Construction in progress 2,668 516 27,376 24,582 Less: Accumulated depreciation and amortization (5,527) (4,779) $ 21,849 $ 19,803 Depreciation and amortization expense for the three months ended March 31, 2022 and March 31, 2021 was approximately $0.7 million and $0.5 million, respectively.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	3 Months Ended
Accrued Expenses and Other Current Liabilities	Mar. 31, 2022
Accrued Expenses and Other Current Liabilities
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) March 31, 2022 December 31, 2021 Accrued manufacturing expenses $ 9,859 $ 8,039 Accrued employee compensation and benefits 1,325 3,234 Accrued external research and development expenses 3,671 2,507 Accrued professional fees 1,595 983 Other 67 87 $ 16,517 $ 14,850

Stockholders' Equity

Stockholders' Equity	3 Months Ended
Stockholders' Equity	Mar. 31, 2022
Stockholders' Equity
Stockholders' Equity	7. Stockholders’ Equity Common Stock As of March 31, 2022 and December 31, 2021, the Company’s certificate of incorporation, as amended and restated, authorized the Company to issue 200,000,000 shares of common stock, $0.0001 par value per share. On June 30, 2020, the Company completed its initial public offering of its common stock and issued and sold 14,375,000 shares of common stock, at a public offering price of $17.00 per share, for gross proceeds of $244.4 million, or net proceeds of $223.8 million after deducting underwriting discounts, commissions, and offering expenses. In August 2021, the Company entered into the ATM Sales Agreement with Cowen to issue and sell from time to time at prevailing market prices, up to $100.0 million in shares of the Company’s common stock. As of March 31, 2022, the Company has not yet issued or sold any securities under the ATM Sales Agreement. Preferred Stock As of March 31, 2022 and December 31, 2021, the Company’s certificate of incorporation, as amended and restated, authorized the Company to issue 5,000,000 shares of preferred stock, $0.0001 par value per share. As of March 31, 2022 and December 31, 2021, no shares of preferred stock were issued or outstanding .

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
Stock-Based Compensation	Mar. 31, 2022
Stock-Based Compensation
Stock-Based Compensation	8 2016 Stock Plan The Company’s 2016 Stock Plan (the “2016 Plan”) provides for the Company to grant incentive stock options or non-qualified stock options, restricted stock, restricted stock units, and other equity awards to employees, directors, and consultants of the Company. The 2016 Plan is administered by the board of directors or, at the discretion of the board of directors, by a committee of the board of directors. The board of directors may also delegate to one or more officers of the Company the power to grant awards to employees and certain officers of the Company. The exercise prices, vesting, and other restrictions are determined at the discretion of the board of directors, or its committee or any such officer if so delegated. Stock options granted under the 2016 Plan with service-based vesting conditions generally vest over four years ten years As of March 31, 2022 and December 31, 2021, no shares remained available for future issuance under the 2016 Plan. 2020 Stock Plan On May 28, 2020, the Company’s board of directors adopted, and on June 17, 2020 its stockholders approved, the 2020 Stock Plan (the “2020 Plan”). The 2020 Plan provides for the grant of incentive stock options, non-statutory stock options, stock appreciation rights, restricted stock awards, restricted stock units, and other stock-based awards. The number of shares initially reserved for issuance under the 2020 Plan is the sum of 4,294,594, plus the number of shares (up to 3,622,691 shares) equal to the sum of (i) the number of shares remaining available for issuance under the 2016 Plan upon the effectiveness of the 2020 Plan and (ii) the number of shares of common stock subject to outstanding awards granted under the 2016 Plan that expire, terminate or are otherwise surrendered, cancelled, forfeited or repurchased by the Company at their original issuance price pursuant to a contractual repurchase right. The number of shares of common stock that may be issued under the 2020 Plan will automatically increase on the first day of each fiscal year, beginning with the fiscal year ending December 31, 2021 and continuing for each fiscal year until, and including, the fiscal year ending December 31, 2030, equal to the lowest of (i) 2,728,610 shares, (ii) 4% of the number of shares of common stock outstanding on such date, and (iii) an amount determined by the Company’s board of directors. On January 1, 2022, the number of shares reserved for issuance under the 2020 Plan increased, pursuant to the terms of the 2020 Plan, by an additional 1,379,937 shares, equal to 4% of the Company’s then outstanding common stock. The shares of common stock underlying any awards that are forfeited, cancelled, held back upon exercise or settlement of an award to satisfy the exercise price or tax withholding, repurchased or are otherwise terminated by the Company under the 2020 Plan will be added back to the shares of common stock available for issuance under the 2020 Plan. As of March 31, 2022, the total number of shares of common stock available for issuance under the 2020 Plan is 4,606,996 shares. 2020 Employee Stock Purchase Plan On May 28, 2020, the Company’s board of directors adopted, and on June 17, 2020 its stockholders approved, the 2020 Employee Stock Purchase Plan (the “2020 ESPP”). A total of 360,651 shares of common stock were initially reserved for issuance under this plan. The number of shares of common stock that may be issued under the 2020 ESPP will automatically increase on the first day of each fiscal year, beginning with the fiscal year commencing on January 1, 2021 and continuing for each fiscal year until, and including, the fiscal year commencing on January 1, 2031, equal to the lowest of (i) 640,630 shares, (ii) 1% of the number of shares of common stock outstanding on such date, and (iii) an amount determined by the Company’s board of directors. On January 1, 2022, the number of shares reserved for issuance under the 2020 ESPP increased, pursuant to the terms of the 2020 ESPP, by an additional 344,984 shares, equal to 1% of the Company’s then outstanding common stock. As of March 31, 2022, the total number of shares of common stock available for issuance under the 2020 ESPP is 1,049,472. Stock Option Valuation The fair value of stock option grants is estimated using the Black-Scholes option-pricing model. The Company historically has been a private company and lacks company-specific historical and implied volatility information. Therefore, it estimates its expected stock volatility based on the historical volatility of a publicly traded set of peer companies and expects to continue to do so until such time as it has adequate historical data regarding the volatility of its own traded stock price. For options with service-based vesting conditions, the expected term of the Company’s stock options has been determined utilizing the “simplified” method for awards that qualify as “plain-vanilla” options. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield is based on the fact that the Company has never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future. Stock Options The following table summarizes the Company’s stock option activity since December 31, 2021: Weighted ‑ Weighted ‑ Average Average Aggregate Number of Exercise Contractual Intrinsic Shares Price Term (in years) Value (in thousands) Outstanding as of December 31, 2021 4,392,836 $ 11.71 8.3 $ 6,801 Granted 1,601,700 $ 5.80 Exercised (107,060) $ 2.05 Forfeited and cancelled (158,863) $ 13.98 Outstanding as of March 31, 2022 5,728,613 $ 10.20 8.7 $ 1,976 Vested and expected to vest as of March 31, 2022 5,728,613 $ 10.20 8.7 $ 1,976 Options exercisable as of March 31, 2022 1,579,119 $ 9.87 7.9 $ 1,451 The weighted-average grant-date fair value of stock options granted during the three months ended March 31, 2022 and 2021 was $4.11 per share and $12.14 per share, respectively. Early Exercise of Stock Options into Restricted Stock Certain option grants permit option holders to elect to exercise unvested options in exchange for unvested common stock. The options that are exercised prior to vesting will continue to vest according to the respective option agreement, and such unvested shares are subject to repurchase by the Company at the optionee’s original exercise price in the event the optionee’s service with the Company voluntarily or involuntarily terminates. A summary of the Company’s unvested common stock from option early exercises that is subject to repurchase by the Company is as follows: Shares Unvested restricted common stock as of December 31, 2021 14,070 Vested (3,775) Unvested restricted common stock as of March 31, 2022 10,295 Proceeds from the early exercise of options are recorded as a liability within accrued expenses and other current liabilities on the condensed consolidated balance sheet. The liability for unvested common stock subject to repurchase is then reclassified to additional paid-in capital as the Company’s repurchase right lapses. The shares purchased by the employees and directors pursuant to the early exercise of stock options are not deemed, for accounting purposes, to be outstanding until those shares have vested. As of March 31, 2022 and December 31, 2021, the liability related to the payments for unvested shares from early-exercised options was less than $0.1 million at each date. Restricted Common Stock Awards The Company has both (i) granted restricted stock awards, with the recipient not paying for the shares of common stock, and (ii) issued and sold restricted stock, with the recipient purchasing the common stock at its fair value per share. In both circumstances, the restricted shares of common stock have service-based vesting conditions and unvested shares are either subject to forfeiture by the employee or subject to repurchase by the Company, at the lesser of holder’s original purchase price or fair value, in the event the holder’s service with the Company voluntarily or involuntarily terminates. Service-based restricted stock awards generally vest over four years Proceeds from the issuance and sale of restricted common stock are recorded as a liability within accrued expenses and other current liabilities on the condensed consolidated balance sheet. The liability for unvested common stock subject to repurchase is then reclassified to additional paid-in capital as the Company’s repurchase right lapses. Shares of restricted common stock granted or sold to employees and directors are not deemed, for accounting purposes, to be outstanding until those shares have vested. The Company did not grant or sell restricted common stock awards during 2021 or the three months ended March 31, 2022. As of March 31, 2022, there was no remaining liability related to the payments received for shares of unvested restricted stock. As of December 31, 2021, the liability related to the payments received for shares of unvested restricted stock was less than $0.1 million. The following table summarizes the Company’s restricted common stock award activity for the three months ended March 31, 2022: Weighted ‑ Average Grant ‑ Date Shares Fair Value Unvested restricted common stock as of December 31, 2021 770 $ 0.85 Vested (770) 0.85 Unvested restricted common stock as of March 31, 2022 — $ — The total fair value of restricted common stock vested during the three months ended March 31, 2022 was less than $0.1 million. Stock-Based Compensation The Company records compensation cost for all stock-based payment arrangements, including employee, director, and consultant stock options and restricted stock. The Company recorded stock-based compensation expense in the following expense categories of its consolidated statements of operations and comprehensive loss (in thousands): Three Months Ended March 31, 2022 2021 Research and development expenses $ 997 $ 954 General and administrative expenses 1,629 1,046 $ 2,626 $ 2,000 As of March 31, 2022, there was $28.5 million of unrecognized compensation cost related to unvested stock options, which is expected to be recognized over a weighted-average period of 2.9 years.

License Agreements

License Agreements	3 Months Ended
License Agreements	Mar. 31, 2022
License Agreements
License Agreements	9. License Agreements License Agreement with Massachusetts Eye and Ear In October 2017, the Company entered into a license agreement with Massachusetts Eye and Ear Infirmary and the Schepens Eye Research Institute, Inc. (collectively referred to as “MEE”) (the “MEE License”). Under the MEE License, the Company received an exclusive, non-transferable, sublicensable, worldwide, royalty-bearing license to certain patent rights and know-how, including rights related to adeno-associated virus (“AAV”) ancestral technology, including AAVAnc80, to use, research, develop, manufacture, and commercialize licensed products in the treatment, diagnosis, and prevention of any and all balance disorders, including hearing disorders of the inner ear, in each case, with a total prevalence in the United States of less than 3,000 patients, and an exclusive, non-transferable, sublicensable right and license under MEE’s rights, title, and interest in certain patents co-owned by MEE and Children’s Medical Center Corporation to use, research, develop, manufacture, and commercialize licensed products. The Company is obligated to use commercially reasonable efforts to develop and commercialize the MEE licensed products, including filing an investigational new drug application (“IND”) in the United States or investigational medicinal product dossier (“IMPD”) in any country in the European Union or an equivalent application in any country within 18 months of completion of specified toxicology studies for a licensed product. Upon entering into the MEE License in 2017, the Company issued to MEE shares of the Company’s common stock then having a fair value of $0.1 million. The Company is obligated to make aggregate milestone payments to MEE of up to $17.7 million upon the achievement of specified development, regulatory, and sales milestones. The Company is also obligated to pay tiered royalties of a mid to high single-digit percentage based on annual net sales of licensed products by the Company and any of its affiliates and sublicensees. Royalties will be paid by the Company on a licensed product-by-licensed product and country-by-country basis beginning after the first commercial sale of an MEE licensed product and lasting until the later of (i) the expiration of the last valid claim in the licensed patents or (ii) ten years The MEE License remains in effect until the last expiration date of the last to expire MEE Royalty Term, unless terminated earlier. The Company has the right to terminate the MEE License at will, with or without cause, by 90 days’ advance written notice to MEE or upon MEE’s material breach of the MEE License, provided that MEE does not cure such material breach within a specified period. MEE has the right to terminate the MEE License in its entirety if (i) the Company fails to make any payment due within a specified period after MEE notifies the Company of such failure, (ii) the Company or its affiliates challenge the validity of the licensed patent rights, (iii) the Company fails to maintain required insurance, or (iv) the Company becomes insolvent or bankrupt. MEE also has the right to terminate the Company’s rights to specific intellectual property rights it has licensed to the Company under the MEE License if the Company materially breaches certain diligence obligations and does not cure within a specified period after written notice from MEE. During the three months ended March 31, 2022 and 2021, the Company did not make any payments to MEE or recognize any research and development expenses under the MEE License. Sublicense Agreement with Lonza Houston, Inc. In October 2017, the Company entered into a sublicense agreement with Lonza Houston, Inc. (“Lonza”), as amended in December 2018 (the “Lonza Sublicense”). Under the agreement, the Company received an exclusive, non-transferable, sublicensable, worldwide, royalty-bearing sublicense to certain patent rights and know-how related to AAV ancestral technology, including AAVAnc80, to use, research, develop, manufacture, and commercialize licensed products for the treatment, diagnosis, and prevention of any and all balance disorders or diseases pertaining to the inner ear and/or any and all hearing diseases or disorders, including hearing disorders of the inner ear, but excluding all such disorders or diseases with a total prevalence in the United States of less than 3,000 patients. The Company is obligated to use commercially reasonable efforts to develop and commercialize the Lonza sublicensed products, including filing an IND in the United States or IMPD in any country in the European Union or an equivalent application in any country within 18 months of completion of specified toxicology studies for a licensed product. Upon entering into the Lonza Sublicense in 2017, the Company issued to Lonza shares of the Company’s common stock then having a fair value of $0.1 million. The Company is obligated to make aggregate milestone payments to Lonza of up to $18.5 million upon the achievement of specified development, regulatory, and sales milestones. The Company is also obligated to pay tiered royalties of a mid to high single-digit percentage based on annual net sales of licensed products by the Company and any of its affiliates and sublicensees as denoted in the Lonza Sublicense. Royalties will be paid by the Company on a licensed product-by-licensed product and country-by-country basis beginning after the first commercial sale of a Lonza sublicensed product and lasting until the later of (i) the expiration of the last valid claim in the patent or (ii) ten years The Lonza Sublicense remains in effect until the last expiration date of the last to expire Lonza Royalty Term, unless terminated earlier. The Company has the right to terminate the Lonza Sublicense at will, with or without cause, by 90 days’ advance written notice to Lonza or upon Lonza’s material breach of the Lonza Sublicense, provided that Lonza does not cure such material breach within a specified period. Lonza has the right to terminate the Lonza Sublicense in its entirety if (i) the Company fails to make any payment due within a specified period after Lonza notifies the Company of such failure, (ii) the Company or its affiliates challenge the validity of the sublicensed patent rights, (iii) the Company fails to maintain required insurance, or (iv) the Company becomes insolvent or bankrupt. Lonza also has the right to terminate the Company’s rights to specific intellectual property rights it has sublicensed to the Company under the Lonza Sublicense if the Company materially breaches certain diligence obligations and does not cure within a specified period after written notice from Lonza. During the three months ended March 31, 2022 and 2021 the Company did not make any payments to Lonza or recognize any research and development expenses under the Lonza Sublicense.

Leases

Leases	3 Months Ended
Leases	Mar. 31, 2022
Leases
Leases	10. Leases The Company leases its office and laboratory facility in Boston, Massachusetts pursuant to a lease agreement entered into in December 2018 (the “2018 Lease”), which includes a lease incentive, fixed payment escalations, and a rent holiday. The 2018 Lease term commenced in May 2019, which was the point at which the Company obtained control of the leased premises, and expires in February 2028. Under the 2018 Lease, the Company is entitled to one option to extend the lease term for an additional five years Leases The Company entered into an amendment in January 2021 to its 2018 Lease (the “Amended 2018 Lease”). Under the Amended 2018 Lease, the Company’s leased space expanded the 2018 leased premises to include an additional 37,500 square feet for a total of approximately 75,000 square feet and extended the term of the 2018 Lease for a new ten-year term. The term extension of existing square feet under the 2018 Lease is accounted for as a lease modification, which resulted in the remeasurement of the existing right-of-use asset and lease liability of $5.9 million and $13.1 million, respectively, to $11.5 million and $18.7 million, respectively, in January 2021, the effective date of the Amended 2018 Lease agreement, and is accounted for as an operating lease. The lease term of the additional leased premises commenced in April 2021 , which was the point at which the Company obtained control of the leased premises. On commencement date the Company recorded a right-of-use asset and lease liability of $9.9 million, respectively, and is accounted for as an operating lease. The Amended 2018 Lease included a landlord-provided tenant improvement allowance of up to $7.1 million to be applied to the costs of the construction of leasehold improvements. The Company determined that it owns the leasehold improvements related to the amended 2018 Lease and, as such, reflected the $7.1 million lease incentive as a reduction of the rental payments used to measure the operating lease liability, and, in turn, the operating lease right-of-use asset as of the lease commencement date in April 2021. As of March 31, 2022, the Company has not yet received any payment reimbursements from the lessor for leasehold improvement costs related to the Amended 2018 Lease. The components of the Company’s lease expense are as follows: (in thousands) March 31, 2022 Operating lease cost $ 1,116 Variable lease cost $ 85 Supplemental disclosure of cash flow information related to leases was as follows: (in thousands) March 31, 2022 Cash paid for amounts included in the measurement of operating lease liabilities (operating cash flows) $ 792 The weighted-average remaining lease term and discount rate were as follows: March 31, 2022 December 31, 2021 Weighted‑average remaining lease term (in years) used for: Operating leases 9.75 10.00 Weighted‑average discount rate used for: Operating leases 10.00 % 10.00 % Because the interest rate implicit in the lease was not readily determinable, the borrowing rate was used to calculate the present value of the Amended 2018 Lease. In determining its incremental borrowing rate, the Company considered its credit quality and assessed interest rates available in the market for similar borrowings, adjusted for the impact of collateral over the term of the lease. Future annual lease payments under the Amended 2018 Lease as of March 31, 2022 were as follows (in thousands): Years Ending December 31, Operating Leases 2022 $ (4,597) 2023 5,020 2024 5,611 2025 5,786 2026 5,959 Thereafter 34,419 Total future lease payments 52,198 Less: Imputed interest (23,072) Total lease liabilities $ 29,126 The following table presents lease assets and liabilities and their classification on the consolidated balance sheet (in thousands): March 31, December 31, Leases Consolidated Balance Sheet Classification (unaudited) 2022 2021 Assets: Operating lease assets Operating lease right‑of‑use assets $ 20,167 $ 20,341 Total lease assets $ 20,167 $ 20,341 Liabilities: Current: Operating lease liabilities Operating lease liabilities $ 711 $ 671 Non‑current: Operating lease liabilities Operating lease liabilities, net of current portion 28,415 28,304 Total lease liabilities $ 29,126 $ 28,975

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
Commitments and Contingencies	Mar. 31, 2022
Commitments and Contingencies
Commitments and Contingencies	11. Commitments and Contingencies 401(k) Plan The Company has a defined-contribution plan under Section 401(k) of the Internal Revenue Code of 1986 (the “401(k) Plan”). The 401(k) Plan covers all employees who meet defined minimum age and service requirements and allows participants to defer a portion of their annual compensation on a pre-tax basis. The Company has made contributions to the 401(k) plan and recorded contribution expense of $0.2 million for the three months ended March 31, 2022. The Company did not make any contributions during the three month period ended March 31, 2021. Indemnification Agreements In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, contract research organizations, business partners, and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with members of its board of directors and certain of its executive officers that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. The Company has not incurred any material costs as a result of such indemnifications and is not currently aware of any indemnification claims. Legal Proceedings 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 the authoritative guidance that addresses accounting for contingencies. The Company expenses as incurred the costs related to such legal proceedings.

Net Loss per Share

Net Loss per Share	3 Months Ended
Net Loss per Share	Mar. 31, 2022
Net Loss per Share
Net Loss per Share	12. Net Loss per Share Net Loss per Share Basic and diluted net loss per share attributable to common stockholders was calculated as follows: Three Months Ended March 31, (in thousands, except share and per share data) 2022 2021 Numerator: Net loss attributable to common stockholders $ (26,983) $ (16,086) Denominator: Weighted‑average common shares outstanding, basic and diluted 34,528,992 34,284,419 Net loss per share attributable to common stockholders, basic and diluted $ (0.78) $ (0.47) The Company’s potential dilutive securities have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share. Therefore, the weighted-average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common stockholders is the same. The Company excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect: March 31, 2022 2021 Unvested restricted common stock 10,295 90,844 Stock options to purchase common stock 5,728,613 4,356,486 5,738,908 4,447,330

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2022
Summary of Significant Accounting Policies
Recently Adopted and Issued Accounting Pronouncements	Recently Adopted Accounting Pronouncements In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU ”) Income Taxes Recently Issued Accounting Pronouncements From time to time, new accounting pronouncements are issued by the FASB or other standard-setting bodies that the Company adopts as of the specified effective date. The Company qualifies as an “emerging growth company” as defined in the Jumpstart Our Business Startups Act of 2012 and has elected not to “opt out” of the extended transition period related to complying with new or revised accounting standards, which means that when a standard is issued or revised and it has different application dates for public and non-public companies, the Company can adopt the new or revised standard at the time non-public companies adopt the new or revised standard and can do so until such time that the Company either (i) irrevocably elects to “opt out” of such extended transition period or (ii) no longer qualifies as an emerging growth company. The Company may choose to early adopt any new or revised accounting standards whenever such early adoption is permitted for non-public companies. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments Codification Improvements to Topic 326, Financial Instruments—Credit Losses Financial Instruments—Credit Losses (Topic 326): Targeted Transition Relief

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
Fair Value Measurements (Tables)	Mar. 31, 2022
Fair Value Measurements
Schedule of fair value hierarchy for its assets and liabilities that are measured at fair value on a recurring basis	Fair Value Measurements at March 31, 2022 Using: (in thousands) Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 55,895 $ — $ — $ 55,895 Restricted cash: Money market funds 2,448 — — 2,448 Marketable securities: U.S. Treasury notes — 154,716 — 154,716 $ 58,343 $ 154,716 $ — $ 213,059 Fair Value Measurements at December 31, 2021 Using: (in thousands) Level 1 Level 2 Level 3 Total Assets: Cash equivalents: Money market funds $ 121,018 $ — $ — $ 121,018 Restricted cash: Money market funds 2,448 — — 2,448 Marketable securities: U.S. Treasury notes — 110,545 — 110,545 $ 123,466 $ 110,545 $ — $ 234,011

Marketable Securities (Tables)

Marketable Securities (Tables)	3 Months Ended
Marketable Securities (Tables)	Mar. 31, 2022
Marketable securities
Schedule of the fair value of available-for-sale marketable debt securities by type of security	March 31, 2022 Gross Gross Amortized Unrealized Unrealized Fair (in thousands) Cost Gain Loss Value Assets Marketable securities: U.S. Treasury notes $ 155,451 $ — $ (735) $ 154,716 $ 155,451 $ — $ (735) $ 154,716 December 31, 2021 Gross Gross Amortized Unrealized Unrealized Fair (in thousands) Cost Gain Loss Value Assets Marketable securities: U.S. Treasury notes $ 110,747 $ — $ (202) $ 110,545 $ 110,747 $ — $ (202) $ 110,545

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	3 Months Ended
Property and Equipment, Net (Tables)	Mar. 31, 2022
Property and Equipment, Net
Schedule of property and equipment, net	(in thousands) March 31, 2022 December 31, 2021 Laboratory equipment $ 8,226 $ 7,595 Furniture and fixtures 611 600 Leasehold improvements 15,871 15,871 Construction in progress 2,668 516 27,376 24,582 Less: Accumulated depreciation and amortization (5,527) (4,779) $ 21,849 $ 19,803

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	3 Months Ended
Accrued Expenses and Other Current Liabilities (Tables)	Mar. 31, 2022
Accrued Expenses and Other Current Liabilities
Schedule of accrued expenses and other current liabilities	(in thousands) March 31, 2022 December 31, 2021 Accrued manufacturing expenses $ 9,859 $ 8,039 Accrued employee compensation and benefits 1,325 3,234 Accrued external research and development expenses 3,671 2,507 Accrued professional fees 1,595 983 Other 67 87 $ 16,517 $ 14,850

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
Stock-Based Compensation (Tables)	Mar. 31, 2022
Stock-Based Compensation
Schedule of stock option activity	Weighted ‑ Weighted ‑ Average Average Aggregate Number of Exercise Contractual Intrinsic Shares Price Term (in years) Value (in thousands) Outstanding as of December 31, 2021 4,392,836 $ 11.71 8.3 $ 6,801 Granted 1,601,700 $ 5.80 Exercised (107,060) $ 2.05 Forfeited and cancelled (158,863) $ 13.98 Outstanding as of March 31, 2022 5,728,613 $ 10.20 8.7 $ 1,976 Vested and expected to vest as of March 31, 2022 5,728,613 $ 10.20 8.7 $ 1,976 Options exercisable as of March 31, 2022 1,579,119 $ 9.87 7.9 $ 1,451
Schedule of unvested common stock from option early exercises	Shares Unvested restricted common stock as of December 31, 2021 14,070 Vested (3,775) Unvested restricted common stock as of March 31, 2022 10,295
Schedule of restricted common stock award activity	Weighted ‑ Average Grant ‑ Date Shares Fair Value Unvested restricted common stock as of December 31, 2021 770 $ 0.85 Vested (770) 0.85 Unvested restricted common stock as of March 31, 2022 — $ —
Schedule of stock based compensation expense	The Company recorded stock-based compensation expense in the following expense categories of its consolidated statements of operations and comprehensive loss (in thousands): Three Months Ended March 31, 2022 2021 Research and development expenses $ 997 $ 954 General and administrative expenses 1,629 1,046 $ 2,626 $ 2,000

Leases (Tables)

Leases (Tables)	3 Months Ended
Leases (Tables)	Mar. 31, 2022
Leases
Schedule of lease costs, supplemental disclosure, weighted average lease term and discount rate and lease classification	(in thousands) March 31, 2022 Operating lease cost $ 1,116 Variable lease cost $ 85 Supplemental disclosure of cash flow information related to leases was as follows: (in thousands) March 31, 2022 Cash paid for amounts included in the measurement of operating lease liabilities (operating cash flows) $ 792 The weighted-average remaining lease term and discount rate were as follows: March 31, 2022 December 31, 2021 Weighted‑average remaining lease term (in years) used for: Operating leases 9.75 10.00 Weighted‑average discount rate used for: Operating leases 10.00 % 10.00 %
Schedule of future annual payments under operating lease	Future annual lease payments under the Amended 2018 Lease as of March 31, 2022 were as follows (in thousands): Years Ending December 31, Operating Leases 2022 $ (4,597) 2023 5,020 2024 5,611 2025 5,786 2026 5,959 Thereafter 34,419 Total future lease payments 52,198 Less: Imputed interest (23,072) Total lease liabilities $ 29,126
Schedule of lease assets and liabilities and their classification on the consolidated balance sheet	The following table presents lease assets and liabilities and their classification on the consolidated balance sheet (in thousands): March 31, December 31, Leases Consolidated Balance Sheet Classification (unaudited) 2022 2021 Assets: Operating lease assets Operating lease right‑of‑use assets $ 20,167 $ 20,341 Total lease assets $ 20,167 $ 20,341 Liabilities: Current: Operating lease liabilities Operating lease liabilities $ 711 $ 671 Non‑current: Operating lease liabilities Operating lease liabilities, net of current portion 28,415 28,304 Total lease liabilities $ 29,126 $ 28,975

Net Loss per Share (Tables)

Net Loss per Share (Tables)	3 Months Ended
Net Loss per Share (Tables)	Mar. 31, 2022
Net Loss per Share
Schedule of net loss per share	Three Months Ended March 31, (in thousands, except share and per share data) 2022 2021 Numerator: Net loss attributable to common stockholders $ (26,983) $ (16,086) Denominator: Weighted‑average common shares outstanding, basic and diluted 34,528,992 34,284,419 Net loss per share attributable to common stockholders, basic and diluted $ (0.78) $ (0.47)
Schedule of securities excluded from computation of net loss per share	March 31, 2022 2021 Unvested restricted common stock 10,295 90,844 Stock options to purchase common stock 5,728,613 4,356,486 5,738,908 4,447,330

Nature of the Business and Ba_2

Nature of the Business and Basis of Presentation (Details) - USD ($) $ / shares in Units, $ in Thousands	Jun. 30, 2020	Aug. 31, 2021	Mar. 31, 2022	Dec. 31, 2021
Temporary Equity [Line Items]
Accumulated deficit			$ (195,378)	$ (168,395)
Scenario, Plan [Member]
Temporary Equity [Line Items]
Gross proceeds to be received from issuance of common stock		$ 100,000
Commission for sale of stock, per agreement, as a percent		3.00%
Common Stock
Temporary Equity [Line Items]
Issuance of common stock upon completion of initial public offering, net of commissions, underwriting discounts and offering costs, shares	14,375,000
Share price	$ 17
Value of shares issued	$ 223,800
Shares issued, gross proceeds	$ 244,400

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Thousands	3 Months Ended
Fair Value Measurements (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Fair Value, Transfers Between Level 1 and Level 2, Description and Policy [Abstract]
Transfer of fair value asset, Level 1 into Level 2	$ 0	$ 0
Transfer of fair value asset, Level 2 into Level 1	0	0
Transfer of fair value asset, into Level 3	0	0
Transfer of fair value asset, out of Level 3	0	$ 0
Recurring
Assets:
Assets	213,059		$ 234,011
Recurring \| Money market funds
Assets:
Cash equivalents	55,895		121,018
Restricted cash	2,448		2,448
Recurring \| US Treasury Securities [Member]
Assets:
Marketable securities	154,716		110,545
Recurring \| Level 1
Assets:
Assets	58,343		123,466
Recurring \| Level 1 \| Money market funds
Assets:
Cash equivalents	55,895		121,018
Restricted cash	2,448		2,448
Recurring \| Level 2
Assets:
Assets	154,716		110,545
Recurring \| Level 2 \| US Treasury Securities [Member]
Assets:
Marketable securities	$ 154,716		$ 110,545

Marketable Securities (Details)

Marketable Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Marketable securities, Amortized Cost	$ 155,451	$ 110,747
Unrealized loss	(735)	(202)
Fair market value	154,716	110,545
US Treasury Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Marketable securities, Amortized Cost	155,451	110,747
Unrealized loss	(735)	(202)
Fair market value	$ 154,716	$ 110,545

Property and Equipment, Net (De

Property and Equipment, Net (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Property and Equipment
Property and equipment, Gross	$ 27,376		$ 24,582
Less: Accumulated depreciation and amortization	(5,527)		(4,779)
Property and Equipment, Net	21,849		19,803
Depreciation and amortization expense	748	$ 544
Laboratory equipment
Property and Equipment
Property and equipment, Gross	8,226		7,595
Furniture and fixtures
Property and Equipment
Property and equipment, Gross	611		600
Leasehold improvements
Property and Equipment
Property and equipment, Gross	15,871		15,871
Construction in progress
Property and Equipment
Property and equipment, Gross	$ 2,668		$ 516

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Accrued Expenses and Other Current Liabilities
Accrued manufacturing expenses	$ 9,859	$ 8,039
Accrued employee compensation and benefits	1,325	3,234
Accrued external research and development expenses	3,671	2,507
Accrued professional fees	1,595	983
Other	67	87
Total	$ 16,517	$ 14,850

Stockholders' Equity (Details)

Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Millions	Jun. 30, 2020	Mar. 31, 2022	Dec. 31, 2021	Aug. 31, 2021
Class of Stock [Line Items]
Common Stock, Shares Authorized		200,000,000	200,000,000
Common Stock, Par or Stated Value Per Share		$ 0.0001	$ 0.0001
Preferred Stock, Shares Authorized		5,000,000	5,000,000
Preferred Stock, Par or Stated Value Per Share		$ 0.0001	$ 0.0001
Preferred Stock, Shares Issued		0	0
Preferred Stock, Shares Outstanding		0	0
Scenario, Plan [Member]
Class of Stock [Line Items]
Gross proceeds to be received from issuance of common stock				$ 100
Common Stock
Class of Stock [Line Items]
Issuance of common stock upon completion of initial public offering, net of commissions, underwriting discounts and offering costs, shares	14,375,000
Share Price	$ 17
Shares issued, gross proceeds	$ 244.4
Issuance of common stock upon completion of initial public offering, net of commissions, underwriting discounts and offering costs	$ 223.8

Stock-Based Compensation (Detai

Stock-Based Compensation (Details) - shares	Jan. 01, 2022	Jun. 17, 2020	Mar. 31, 2022
2016 Plan
Stock-Based Compensation
Remaining shares available for issuance			0
2016 Plan \| Stock option
Stock-Based Compensation
Vesting period			4 years
Expiration period			10 years
2020 Stock Plan
Stock-Based Compensation
Remaining shares available for issuance			4,606,996
Number of shares authorized, fixed portion		4,294,594
Number of shares authorized, variable portion		3,622,691
Annual increase in shares reserved for issuance		2,728,610
Increase in shares reserved for issuance	1,379,937
Annual increase in shares reserved for issuance, as a percent of stock outstanding	4.00%	4.00%
2020 Employee Stock Purchase Plan
Stock-Based Compensation
Remaining shares available for issuance			1,049,472
Number of shares authorized, fixed portion		360,651
Annual increase in shares reserved for issuance		640,630
Increase in shares reserved for issuance	344,984
Annual increase in shares reserved for issuance, as a percent of stock outstanding	1.00%	1.00%

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock option activity (Details) - Stock option - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Number of Shares
Outstanding as at beginning of period (in shares)	4,392,836
Granted (in shares)	1,601,700
Exercised (in shares)	(107,060)
Forfeited and cancelled (in shares)	(158,863)
Outstanding as at end of period (in shares)	5,728,613		4,392,836
Vested and expected to vest as at end of period (in shares)	5,728,613
Options exercisable as at end of period (in shares)	1,579,119
Weighted Average Exercise Price
Weighted average exercise price outstanding as at beginning of period (in dollars per share)	$ 11.71
Weighted average exercise price, Granted (in dollars per share)	5.80
Weighted average exercise price, Exercised (in dollars per share)	2.05
Weighted average exercise price, Forfeited and cancelled (in dollars per share)	13.98
Weighted average exercise price, Outstanding as at end of period (in dollars per share)	10.20		$ 11.71
Vested and expected to vest as at end of period (in dollars per share)	10.20
Options exercisable as at end of period (in dollars per share)	$ 9.87
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Contractual term, Outstanding (in years)	8 years 8 months 12 days		8 years 3 months 18 days
Contractual term, Vested and expected to vest (in years)	8 years 8 months 12 days
Contractual term, Options exercisable (in years)	7 years 10 months 24 days
Average intrinsic value, Outstanding	$ 1,976		$ 6,801
Average intrinsic value, Vested and expected to vest	1,976
Average intrinsic value, Exercisable	$ 1,451
Weighted-average grant-date fair value of stock options granted	$ 4.11	$ 12.14

Stock-Based Compensation - Earl

Stock-Based Compensation - Early exercise of stock options into restricted stock (Details) $ in Millions	3 Months Ended
	Mar. 31, 2022USD ($)shares
Maximum
Stock-Based Compensation
Liability for unvested shares \| $	$ 0.1
Restricted stock from early exercise of options
Stock-Based Compensation
Unvested restricted common stock at beginning of period	14,070
Vested	(3,775)
Unvested restricted common stock at end of period	10,295

Stock-Based Compensation - Rest

Stock-Based Compensation - Restricted common stock award activity (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Restricted stock awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Liability for unvested awards	$ 0
Shares
Unvested restricted common stock at beginning of period	770
Vested	(770)
Unvested restricted common stock at end of period		770
Weighted Average Grant Date Fair Value
Unvested restricted common stock at beginning of period	$ 0.85
Vested	$ 0.85
Unvested restricted common stock at end of period		$ 0.85
Restricted stock awards \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Liability for unvested awards		$ 0.1
Weighted Average Grant Date Fair Value
Total fair value of restricted common stock vested	$ 0.1
Service-based restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
Issued in period	0	0

Stock-Based Compensation - St_2

Stock-Based Compensation - Stock based compensation expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Stock-Based Compensation
Stock-based compensation expense	$ 2,626	$ 2,000
Total unrecognized stock-based compensation expense related to the unvested stockbased awards	$ 28,500
Unrecognized stock-based compensation expense, weighted average period	2 years 10 months 24 days
Research and development expenses
Stock-Based Compensation
Stock-based compensation expense	$ 997	954
General and administrative expenses
Stock-Based Compensation
Stock-based compensation expense	$ 1,629	$ 1,046

License Agreements (Details)

License Agreements (Details) $ in Thousands	1 Months Ended	3 Months Ended
License Agreements (Details) $ in Thousands	Oct. 31, 2017USD ($)	Mar. 31, 2022USD ($)item	Mar. 31, 2021USD ($)
License Agreements
Research and development		$ 20,388	$ 11,258
MEE License
License Agreements
Number of domestic patients \| item		3,000
IND filing period		18 months
Fair value of stock	$ 100
Period for start commercial sale of product		10 years
Number of days for advance written notice		90 days
Research and development		$ 0	0
MEE License \| Maximum
License Agreements
Milestone payment amount		$ 17,700
Lonza Sublicense
License Agreements
Number of domestic patients \| item		3,000
IND filing period		18 months
Fair value of stock	$ 100
Period for start commercial sale of product		10 years
Number of days for advance written notice		90 days
Research and development		$ 0	$ 0
Lonza Sublicense \| Maximum
License Agreements
Milestone payment amount		$ 18,500

Leases (Details)

Leases (Details) $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended
Leases (Details) $ in Thousands	Jan. 31, 2021USD ($)ft²	Mar. 31, 2022USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2021USD ($)	Apr. 30, 2021USD ($)	Jan. 01, 2021USD ($)	Dec. 31, 2018USD ($)
Leases
Option to extend		true
Lease extension period		5 years
Annual base rent		$ 2,300
Percentage of annual increase		3.00%
Letter of credit related to lease agreement		$ 1,300
Amount of tenant lease improvement allowance					$ 7,100		$ 6,600
Increase in area under lease \| ft²	37,500
Area under lease \| ft²	75,000
Lease term	10 years
Operating lease liabilities arising from obtaining right-of-use assets			$ 6,600
Operating Lease, Right-of-Use Asset	$ 11,500	20,167		$ 20,341	9,900	$ 5,900
Operating Lease, Liability	$ 18,700	$ 29,126			$ 9,900	$ 13,100

Leases - Components of lease co

Leases - Components of lease cost (Details) $ in Thousands	3 Months Ended
Leases - Components of lease cost (Details) $ in Thousands	Mar. 31, 2022USD ($)
Lease cost
Operating lease cost	$ 1,116
Variable lease cost	$ 85

Leases - Supplemental disclosur

Leases - Supplemental disclosure of cash flow information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022USD ($)
Cash flow information related to leases
Cash paid for amounts included in the measurement of operating lease liabilities (operating cash flows)	$ 792

Leases - Weighted average infor

Leases - Weighted average information (Details)	Mar. 31, 2022	Dec. 31, 2021
Leases
Weighted-average remaining lease term (in years) used for: Operating Lease	9 years 9 months	10 years
Weighted-average discount rate used for: Operating leases	10.00%	10.00%

Leases - Future annual payments

Leases - Future annual payments (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Apr. 30, 2021	Jan. 31, 2021	Jan. 01, 2021
Operating lease
2022	$ (4,597)
2023	5,020
2024	5,611
2025	5,786
2026	5,959
Thereafter	34,419
Total future lease payments	52,198
Less: Imputed interest	(23,072)
Total lease liabilities	$ 29,126	$ 9,900	$ 18,700	$ 13,100

Leases - Assets and Liabilities

Leases - Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Apr. 30, 2021	Jan. 31, 2021	Jan. 01, 2021
Leases
Operating lease assets	$ 20,167	$ 20,341	$ 9,900	$ 11,500	$ 5,900
Total lease assets	20,167	20,341
Current:
Operating lease liabilities	711	671
Noncurrent:
Operating lease liabilities, net of current portion	28,415	28,304
Total lease liabilities	$ 29,126	$ 28,975

Commitments and Contingencies -

Commitments and Contingencies - 401(k) Plan (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Commitments and Contingencies
Contribution expense	$ 0.2	$ 0

Net Loss per Share (Details)

Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Net Loss per Share
Net loss attributable to common stockholders	$ (26,983)	$ (16,086)
Weighted-average common shares outstanding, basic	34,528,992	34,284,419
Weighted-average common shares outstanding, diluted	34,528,992	34,284,419
Net loss per share attributable to common stockholders, basic	$ (0.78)	$ (0.47)
Net loss per share attributable to common stockholders, diluted	$ (0.78)	$ (0.47)

Net Loss per Share - Antidiluti

Net Loss per Share - Antidilutive securities (Details) - shares	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Net Loss per Share and Unaudited Pro Forma Net Loss per Share
Securities excluded from computation of earnings per share amount	5,738,908	4,447,330
Restricted stock awards
Net Loss per Share and Unaudited Pro Forma Net Loss per Share
Securities excluded from computation of earnings per share amount	10,295	90,844
Stock option
Net Loss per Share and Unaudited Pro Forma Net Loss per Share
Securities excluded from computation of earnings per share amount	5,728,613	4,356,486