Avidity Biosciences (RNA) 10-Q8 Nov 222022 Q3 Quarterly reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2022	Oct. 25, 2022
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Entity Registrant Name	Avidity Biosciences, Inc.
Entity Central Index Key	0001599901
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		54,462,518
Entity File Number	001-39321
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	46-1336960
Entity Address, Address Line One	10578 Science Center Drive
Entity Address, Address Line Two	Suite 125
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92121
City Area Code	858
Local Phone Number	401-7900
Title of 12(b) Security	Common Stock, $0.0001 par value
Trading Symbol	RNA
Security Exchange Name	NASDAQ
Document Quarterly Report	true
Document Transition Report	false

Condensed Balance Sheets

Condensed Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 143,699	$ 320,448
Marketable securities	261,849	85,095
Prepaid and other assets	8,916	5,598
Total current assets	414,464	411,141
Property and equipment, net	6,037	4,805
Restricted cash	251	251
Right-of-use assets	9,264	10,784
Other assets	523	599
Total assets	430,539	427,580
Current liabilities:
Accounts payable and accrued liabilities	26,375	14,085
Accrued compensation	7,747	8,940
Lease liabilities, current portion	3,090	1,769
Deferred revenue, current portion	5,454	4,864
Total current liabilities	42,666	29,658
Lease liabilities, net of current portion	8,185	9,960
Deferred revenue, net of current portion	2,706	6,532
Total liabilities	53,557	46,150
Commitments and contingencies (Note 7)	0	0
Stockholders’ equity:
Common stock, $0.0001 par value; authorized shares – 400,000; issued and outstanding shares – 54,446 and 47,754 at September 30, 2022 and December 31, 2021, respectively	5	5
Additional paid-in capital	688,513	566,161
Accumulated other comprehensive loss	(3,463)	(187)
Accumulated deficit	(308,073)	(184,549)
Total stockholders’ equity	376,982	381,430
Total liabilities and stockholders’ equity	$ 430,539	$ 427,580

Condensed Balance Sheets (Paren

Condensed Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2022	Dec. 31, 2021
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	400,000,000	400,000,000
Common stock, shares issued	54,446,000	47,754,000
Common stock, shares outstanding	54,446,000	47,754,000

Condensed Statements of Operati

Condensed Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Income Statement [Abstract]
Collaboration revenue	$ 2,482	$ 2,163	$ 6,455	$ 7,474
Revenue from Contract with Customer, Product and Service [Extensible Enumeration]	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember
Operating expenses:
Research and development	$ 37,317	$ 24,831	$ 104,794	$ 68,214
General and administrative	10,094	6,612	27,349	18,764
Total operating expenses	47,411	31,443	132,143	86,978
Loss from operations	(44,929)	(29,280)	(125,688)	(79,504)
Other income (expense):
Interest income	1,342	17	2,203	49
Other expense	(12)	(11)	(39)	(16)
Total other income	1,330	6	2,164	33
Net loss	(43,599)	(29,274)	(123,524)	(79,471)
Other comprehensive income (loss):
Net unrealized (losses) gains on marketable securities	(477)	(1)	(3,276)	4
Comprehensive loss	$ (44,076)	$ (29,275)	$ (126,800)	$ (79,467)
Net loss per share, basic	$ (0.82)	$ (0.68)	$ (2.45)	$ (2.01)
Net loss per share, diluted	$ (0.82)	$ (0.68)	$ (2.45)	$ (2.01)
Weighted-average shares outstanding, basic	53,069	43,265	50,432	39,477
Weighted-average shares outstanding, diluted	53,069	43,265	50,432	39,477

Condensed Statements of Stockho

Condensed Statements of Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	ATM	Common Stock	Common Stock ATM	Additional Paid-in Capital	Additional Paid-in Capital ATM	Accumulated Other Comprehensive Loss	Accumulated Deficit
Balance at Dec. 31, 2020	$ 306,223		$ 4		$ 372,764		$ (5)	$ (66,540)
Balance, Shares at Dec. 31, 2020			37,569
Issuance of common stock upon exercise of stock options	24				24
Issuance of common stock upon exercise of stock options, Shares			31
Vesting of early exercise options	10				10
Stock-based compensation	3,701				3,701
Net loss	(23,844)							(23,844)
Other comprehensive gain (loss)	2						2
Balance at Mar. 31, 2021	286,116		$ 4		376,499		(3)	(90,384)
Balance, Shares at Mar. 31, 2021			37,600
Balance at Dec. 31, 2020	306,223		$ 4		372,764		(5)	(66,540)
Balance, Shares at Dec. 31, 2020			37,569
Net loss	(79,471)
Balance at Sep. 30, 2021	394,877		$ 5		540,884		(1)	(146,011)
Balance, Shares at Sep. 30, 2021			46,897
Balance at Mar. 31, 2021	286,116		$ 4		376,499		(3)	(90,384)
Balance, Shares at Mar. 31, 2021			37,600
Issuance of common stock upon exercise of stock options	98				98
Issuance of common stock upon exercise of stock options, Shares			51
Issuance of common stock under employee stock purchase plan	318				318
Issuance of common stock under employee stock purchase plan, Shares			14
Vesting of early exercise options	9				9
Stock-based compensation	4,289				4,289
Net loss	(26,353)							(26,353)
Other comprehensive gain (loss)	3						3
Balance at Jun. 30, 2021	264,480		$ 4		381,213			(116,737)
Balance, Shares at Jun. 30, 2021			37,665
Issuance of common stock upon exercise of stock options	34				34
Issuance of common stock upon exercise of stock options, Shares			32
Vesting of early exercise options	6				6
Issuance of common stock in public offerings, net of issuance costs		$ 155,082		$ 1		$ 155,081
Issuance of common stock in public offerings, net of issuance costs, Shares				9,200
Stock-based compensation	4,550				4,550
Net loss	(29,274)							(29,274)
Other comprehensive gain (loss)	(1)						(1)
Balance at Sep. 30, 2021	394,877		$ 5		540,884		(1)	(146,011)
Balance, Shares at Sep. 30, 2021			46,897
Balance at Dec. 31, 2021	381,430		$ 5		566,161		(187)	(184,549)
Balance, Shares at Dec. 31, 2021			47,754
Issuance of common stock upon exercise of stock options	10				10
Issuance of common stock upon exercise of stock options, Shares			7
Vesting of early exercise options	1				1
Issuance of common stock in public offerings, net of issuance costs		24,103				24,103
Issuance of common stock in public offerings, net of issuance costs, Shares				1,520
Stock-based compensation	6,238				6,238
Net loss	(34,235)							(34,235)
Other comprehensive gain (loss)	(1,839)						(1,839)
Balance at Mar. 31, 2022	375,708		$ 5		596,513		(2,026)	(218,784)
Balance, Shares at Mar. 31, 2022			49,281
Balance at Dec. 31, 2021	$ 381,430		$ 5		566,161		(187)	(184,549)
Balance, Shares at Dec. 31, 2021			47,754
Issuance of common stock upon exercise of stock options, Shares	282
Net loss	$ (123,524)
Balance at Sep. 30, 2022	376,982		$ 5		688,513		(3,463)	(308,073)
Balance, Shares at Sep. 30, 2022			54,446
Balance at Mar. 31, 2022	375,708		$ 5		596,513		(2,026)	(218,784)
Balance, Shares at Mar. 31, 2022			49,281
Issuance of common stock upon exercise of stock options	4				4
Issuance of common stock upon exercise of stock options, Shares			5
Issuance of common stock under employee stock purchase plan	499				499
Issuance of common stock under employee stock purchase plan, Shares			49
Vesting of early exercise options	1				1
Issuance of common stock in public offerings, net of issuance costs		38,281				38,281
Issuance of common stock in public offerings, net of issuance costs, Shares				2,746
Stock-based compensation	6,508				6,508
Net loss	(45,690)							(45,690)
Other comprehensive gain (loss)	(960)						(960)
Balance at Jun. 30, 2022	374,351		$ 5		641,806		(2,986)	(264,474)
Balance, Shares at Jun. 30, 2022			52,081
Issuance of common stock upon exercise of stock options	303				303
Issuance of common stock upon exercise of stock options, Shares			270
Vesting of early exercise options	1				1
Issuance of common stock in public offerings, net of issuance costs		$ 39,317				$ 39,317
Issuance of common stock in public offerings, net of issuance costs, Shares				2,095
Stock-based compensation	7,086				7,086
Net loss	(43,599)							(43,599)
Other comprehensive gain (loss)	(477)						(477)
Balance at Sep. 30, 2022	$ 376,982		$ 5		$ 688,513		$ (3,463)	$ (308,073)
Balance, Shares at Sep. 30, 2022			54,446

Condensed Statements of Stock_2

Condensed Statements of Stockholders' Equity (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021
Common Stock \| ATM
Stock issuance costs	$ 1,216	$ 1,184	$ 745	$ 10,518

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Cash flows from operating activities
Net loss	$ (123,524)	$ (79,471)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	1,006	431
Stock-based compensation expense	19,832	12,540
Amortization of premiums and discounts on marketable securities, net	184	87
Gain on disposal of property and equipment	0	(16)
Changes in operating assets and liabilities:
Prepaid and other assets	(3,242)	(5,654)
Accounts payable and accrued liabilities	12,028	3,869
Accrued compensation	(1,193)	3,001
Operating lease right-of-use assets and liabilities, net	1,066	449
Deferred revenue	(3,236)	(3,834)
Net cash used in operating activities	(97,079)	(68,598)
Cash flows from investing activities
Maturities of marketable securities	85,975	3,580
Purchases of marketable securities	(266,189)	0
Purchases of property and equipment	(1,973)	(2,033)
Net cash (used in) provided by investing activities	(182,187)	1,547
Cash flows from financing activities
Proceeds from issuance of common stock in public offerings, gross	104,846	165,600
Payment of issuance costs related to public offerings	(3,145)	(10,399)
Proceeds from issuance of common stock under employee stock purchase plan	499	318
Proceeds from exercise of stock options	317	156
Payment of deferred financing costs	0	(73)
Net cash provided by financing activities	102,517	155,602
Net (decrease) increase in cash, cash equivalents and restricted cash	(176,749)	88,551
Cash, cash equivalents and restricted cash at beginning of period	320,699	321,713
Cash, cash equivalents and restricted cash at end of period	143,950	410,264
Supplemental schedule of noncash investing and financing activities:
Costs incurred, but not paid, in connection with public offering included in accounts payable and accrued liabilities	0	119
Costs incurred, but not paid, in connection with deferred financing costs included in accounts payable and accrued liabilities	0	61
Costs incurred, but not paid, in connection with purchases of property and equipment included in accounts payable and accrued liabilities	$ 485	$ 134

Description of Business and Bas

Description of Business and Basis of Presentation	9 Months Ended
Description of Business and Basis of Presentation	Sep. 30, 2022
Accounting Policies [Abstract]
Description of Business and Basis of Presentation	1. Description of Business and Basis of Presentation Description of Business Avidity Biosciences, Inc. (the Company or Avidity) is a biopharmaceutical company committed to delivering a new class of RNA therapeutics called Antibody Oligonucleotide Conjugates (AOCs). The Company’s proprietary AOC platform is designed to combine the specificity of monoclonal antibodies with the precision of RNA therapeutics to target the root cause of diseases previously untreatable with such therapeutics. Liquidity On June 16, 2020, the Company completed its initial public offering (IPO), and it has since raised additional financing through additional public offerings and a sales agreement which are described further in Note 8 (Stockholders’ Equity). To date, the Company has devoted substantially all of its resources to organizing and staffing the Company, business planning, raising capital, developing its proprietary AOC platform, identifying potential product candidates, establishing its intellectual property portfolio, conducting research, preclinical and clinical studies, and providing other general and administrative support for these operations. In addition, the Company has a limited operating history, has incurred operating losses since inception and expects that it will continue to incur net losses into the foreseeable future as it continues the development of its product candidates and development programs. As of September 30, 2022, the Company had an accumulated deficit of $308.1 million and cash, cash equivalents and marketable securities of $405.5 million. The Company believes that existing cash, cash equivalents and marketable securities will be sufficient to fund the Company’s operations for at least 12 months from the date of the filing of this Form 10-Q. The Company plans to finance its future cash needs through equity offerings, debt financings or other capital sources, including potential collaborations, licenses and other similar arrangements. If the Company is not able to secure adequate additional funding, it may be forced to make reductions in spending, extend payment terms with suppliers, liquidate assets where possible, and/or delay or reduce the scope of its planned development programs. Any of these actions could materially harm the Company’s business, results of operations and future prospects. Basis of Presentation The accompanying unaudited interim condensed financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) and the rules and regulations of the Securities and Exchange Commission (SEC) related to a quarterly report on Form 10-Q. Certain information and note disclosures normally included in annual financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to those rules and regulations. The unaudited interim condensed financial statements reflect all adjustments which, in the opinion of management, are necessary for a fair statement of the results for the periods presented. All such adjustments are of a normal and recurring nature. The operating results presented in these unaudited interim condensed financial statements are not necessarily indicative of the results that may be expected for any future periods. These unaudited interim condensed financial statements should be read in conjunction with the audited financial statements and the notes thereto for the year ended December 31, 2021 included in the Company’s annual report on Form 10-K filed with the SEC on March 1, 2022.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
Summary of Significant Accounting Policies	Sep. 30, 2022
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Use of Estimates The Company’s condensed financial statements accordance GAAP, which the Company and assumptions that impact the amounts of liabilities, revenues and expenses and the disclosure of contingent and liabilities in the condensed financial statements and accompanying notes. The most significant estimates in the Company’s condensed financial statements to Although these on the Company’s knowledge of events and actions undertake the actual ultimately these and assumptions. Cash, Cash Equivalents and Restricted Cash The Company considers all highly liquid investments with original maturities of three months or less from the date of purchase to be cash equivalents. Cash and cash equivalents include cash in readily available checking and money market accounts. Restricted cash represents cash held as collateral for the letter of credit required under the Company’s facility lease and is reported as a long-term asset in the accompanying condensed balance sheets. Marketable Securities The Company’s marketable securities primarily consist of U.S. Government and corporate debt securities. The Company classifies its marketable securities as available-for-sale and records such assets at estimated fair value in the condensed balance sheets, with unrealized gains and losses, if any, reported as a component of other comprehensive income (loss) within the condensed statements of operations and comprehensive loss and as a separate component of stockholders’ equity. The Company classifies marketable securities with remaining maturities greater than one year as current assets because such marketable securities are available to fund the Company’s current operations. Realized gains and losses are calculated on the specific identification method and recorded as interest income. There were no realized gains and losses during any of the periods presented. At each balance sheet date, the Company assesses available-for-sale securities in an unrealized loss position to determine whether the unrealized loss is other-than-temporary. When the Company determines that a decline in the fair value below its cost basis is other-than-temporary, the Company recognizes an impairment loss in the period in which the other-than-temporary decline occurred. There have been no other-than-temporary impairments recognized during any of the periods presented. See Note 4 (Marketable Securities) for further information. Concentration of Credit Risk Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash, cash equivalents and marketable securities. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company has not experienced any losses in such accounts and believes it is not exposed to significant risk on its cash balances due to the financial position of the depository institutions in which those deposits are held. Additionally, the Company has established guidelines regarding approved investments, credit quality, diversification, liquidity and maturities of investments, which are designed to maintain safety and liquidity. Fair Value of Financial Instruments Certain assets and liabilities are carried at fair value under GAAP. Fair value is defined as 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, 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 and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. The asset’s or liability’s fair value measurement level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. None of the Company’s non-financial assets are recorded at fair value on a non-recurring basis. The carrying amounts reflected in the Company’s condensed balance sheets for prepaid and other assets and accounts payable and accrued liabilities approximate their fair values due to their short-term nature. See Note 3 (Fair Value Measurements) for information on assets measured at fair value. Property and Equipment, net Property and equipment, including leasehold improvements, are stated at cost less accumulated depreciation and amortization. Depreciation and amortization are recorded using the straight-line method over the estimated useful lives of the related assets, which ranges from three to five years. Leasehold improvements are amortized on a straight-line basis over the shorter of the estimated useful lives of the assets or the remaining lease term. Repairs and maintenance charges that do not increase the useful life of the assets are charged to operating expenses as incurred. Impairment of Long-Lived Assets Long-lived assets consist of property and equipment. An impairment loss is recorded if and when events and circumstances indicate that assets might be impaired and the undiscounted cash flows estimated to be generated by those assets are less than the carrying amount of those assets. The Company has not recognized any impairment losses in any of the periods presented in these condensed financial statements. Segment Information Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by management in making decisions regarding resource allocation and assessing performance. The Company manages its operations as a single Revenue Recognition To date, all the Company’s revenue has been derived from collaboration and research agreements. The terms of these arrangements include the following types of payments to the Company: non-refundable, upfront license fees; development, regulatory and commercial milestone payments; payments for research and development services provided by the Company or for manufacturing supply services the Company provides through its contract manufacturers; and royalties on net sales of licensed products. The Company performs the following steps in determining the appropriate amount of revenue to be recognized as it fulfills its obligations under each of these agreements: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations, including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (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 receives payments from its collaborators based on billing schedules established in each contract. Upfront and other payments may require deferral of revenue recognition to a future period until the Company performs its obligations under its research and collaboration arrangements. Amounts are recorded as accounts receivable when the Company’s right to consideration is unconditional. See Note 5 (Collaboration, License and Research Agreements) for further information. Research and Development Costs Research and development costs are expensed as incurred and include salaries, benefits and stock-based compensation associated with research and development personnel, third-party research and development expenses, license fees, laboratory supplies, facilities, overhead costs, and consultants. Nonrefundable advance payments for goods and services that will be used in future research and development activities are capitalized and recorded as expense in the period that the Company receives the goods or when services are performed. Upfront and milestone payments to acquire contractual rights to licensed technology are expensed when incurred if there is uncertainty in the Company receiving future economic benefit from the acquired contractual rights. Certain of these contractual rights may require the Company to make additional milestone payments upon initiation of a pivotal trial and the U.S. Food and Drug Administration approval, which are not expected to exceed $8.5 million. Patent Costs Costs related to filing and pursuing patent applications are recorded as general and administrative expense and expensed as incurred since recoverability of such expenditures is uncertain. Income Taxes The Company accounts for income taxes in accordance with Accounting Standards Codification (ASC) 740, Income Taxes When uncertain tax positions exist, the Company recognizes the tax benefit of tax positions to the extent that the benefit would more likely than not be realized assuming examination by the taxing authority. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position as well as consideration of the available facts and circumstances. The Company is subject to taxation in the United States and various state jurisdictions. As of December 31, 2021, the Company’s tax years since conversion to a corporation in 2019 are subject to examination by taxing authorities. Stock-Based Compensation Stock-based compensation expense for employee and non-employee stock option grants is recorded at the estimated fair value of the award as of the grant date and is recognized as expense on a straight-line basis over the requisite service period (usually the vesting period) of the stock-based award, and forfeitures are recognized as incurred. Stock-based compensation expense for employee stock purchases under the Company’s Employee Stock Purchase Plan (the ESPP) is recorded at the estimated fair value of the purchase as of the plan enrollment date and is recognized as expense on a straight-line basis over the applicable six-month ESPP offering period. The estimation of fair value for stock-based compensation requires management to make estimates and judgments about, among other things, the estimated life of options and volatility of the Company’s common stock. The judgments directly affect the amount of compensation expense that will be recognized. Comprehensive Loss Comprehensive loss is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources, including unrealized gains and losses on marketable securities. Comprehensive gains (losses) have been reflected in the statements of operations and comprehensive loss for all periods presented. Net Loss Per Share Basic net loss per share is computed by dividing the net loss by the weighted-average number of common shares outstanding for the period, adjusted for the weighted-average number of common shares outstanding that are subject to repurchase or forfeiture. The Company has excluded 8,936 and 22,158 weighted-average shares subject to repurchase or forfeiture from the weighted-average number of common shares outstanding for the three months ended September 30, 2022 and 2021, respectively, and 11,435 and 39,345 weighted-average shares subject to repurchase or forfeiture from the weighted-average number of common shares outstanding for the nine months ended September 30, 2022 and 2021, respectively. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of common shares and dilutive common stock equivalents outstanding for the period determined using the treasury-stock and if-converted methods. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding as inclusion of the potentially dilutive securities would be anti-dilutive. Potentially dilutive securities not included in the calculation of diluted net loss per share, because to do so would be anti-dilutive, are as follows (in common stock equivalent shares; in thousands): September 30, 2022 2021 Common stock options issued and outstanding 9,093 5,649 Common stock subject to repurchase or forfeiture 8 18 ESPP shares pending issuance 27 12 Total 9,128 5,679 Recently Issued Accounting Pronouncements From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies that are adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on its financial position or results of operations upon adoption. Accounting Standards Not Yet Adopted In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses: Measurement of Credit Losses on Financial Statements (Topic 326), which intends to improve financial reporting by requiring earlier recognition of credit losses on certain financial assets, such as available-for-sale debt securities. Subsequent to the issuance of ASU 2016-13, the FASB issued several additional Accounting Standard Updates (ASUs) to clarify implementation guidance, provide narrow-scope improvements and provide additional disclosure guidance. In November 2019, the FASB issued an amendment making this ASU effective for fiscal years beginning after December 15, 2022 for smaller reporting companies. The Company was a smaller reporting company at the determination date, and therefore the new standard will be effective for the Company on January 1, 2023. The Company is currently evaluating the potential impact that the adoption of ASU 2016-13 may have on its financial statements and related disclosures.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
Fair Value Measurements	Sep. 30, 2022
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair Value Measurements The Company determines the fair value of its marketable securities based on one or more valuations from its investment accounting and reporting service provider. The investment service provider values the securities using a hierarchical security pricing model that relies primarily on valuations provided by an industry-recognized valuation service. Such valuations may be based on trade prices in active markets for identical assets (Level 1 inputs) or valuation models using inputs that are observable either directly or indirectly (Level 2 inputs), such as quoted prices for similar assets, yield curves, volatility factors, credit spreads, default rates, loss severity, current market and contractual prices for the underlying instruments or debt, and broker and dealer quotes, as well as other relevant economic measures. The following tables summarize the Company’s marketable securities measured at fair value (in thousands): Fair Value Measurements Using As of September 30, 2022 Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Marketable securities: U.S. Treasury securities $ 236,553 $ 236,553 $ — $ — U.S. Government agency securities 4,927 — 4,927 — Negotiable certificates of deposit 3,340 — 3,340 — Corporate debt securities 17,029 — 17,029 — Total $ 261,849 $ 236,553 $ 25,296 $ — Fair Value Measurements Using As of December 31, 2021 Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Marketable securities: U.S. Treasury securities $ 65,372 $ 65,372 $ — $ — Negotiable certificates of deposit 3,873 — 3,873 — Corporate debt securities 15,850 — 15,850 — Total $ 85,095 $ 65,372 $ 19,723 $ —

Marketable Securities

Marketable Securities	9 Months Ended
Marketable Securities	Sep. 30, 2022
Investments Debt And Equity Securities [Abstract]
Marketable Securities	4. Marketable Securities The Company’s marketable securities, which consist of highly liquid marketable debt securities, are classified as available-for-sale and are stated at fair value. The following tables summarize the Company’s marketable securities (in thousands): As of September 30, 2022 Maturity (in years) Amortized Cost Unrealized Gains Unrealized Losses Estimated Fair Value U.S. Treasury securities 1 or less $ 197,652 $ — $ (1,938 ) $ 195,714 U.S. Government agency securities 1 or less 5,000 — (73 ) 4,927 Negotiable certificates of deposit 1 or less 2,683 — (48 ) 2,635 Corporate debt securities 1 or less 16,131 — (344 ) 15,787 U.S. Treasury securities 1 - 2 41,823 — (984 ) 40,839 Negotiable certificates of deposit 1 - 2 734 — (29 ) 705 Corporate debt securities 1 - 2 1,289 — (47 ) 1,242 Total $ 265,312 $ — $ (3,463 ) $ 261,849 As of December 31, 2021 Maturity (in years) Amortized Cost Unrealized Gains Unrealized Losses Estimated Fair Value U.S. Treasury securities 1 or less $ 2,492 $ — $ (1 ) $ 2,491 Negotiable certificates of deposit 1 or less 1,190 — (1 ) 1,189 U.S. Treasury securities 1 - 2 63,034 — (153 ) 62,881 Negotiable certificates of deposit 1 - 2 2,687 — (3 ) 2,684 Corporate debt securities 1 - 2 15,879 — (29 ) 15,850 Total $ 85,282 $ — $ (187 ) $ 85,095 The unrealized losses on the Company’s marketable securities of $3.5 million as of September 30, 2022 were caused by interest rate increases which resulted in the decrease in market value of these securities. Because the decline in fair value is attributable to changes in interest rates and not credit quality, and because the Company does not intend to sell the investments and it is not more likely than not that the Company will be required to sell the investments before recovery of their amortized cost bases, which may be maturity, the Company does not consider those marketable securities to be other-than -temporarily impaired at September 30, 2022. None of the Company’s marketable securities have been in a continuous unrealized loss position for 12 months or greater as of September 30, 2022.

Collaboration, License and Rese

Collaboration, License and Research Agreements	9 Months Ended
Collaboration, License and Research Agreements	Sep. 30, 2022
Collaboration License And Research Agreements [Abstract]
Collaboration, License and Research Agreements	5. Collaboration, License and Research Agreements Research Collaboration and License Agreement with Eli Lilly and Company In April 2019, the Company entered into a Research Collaboration and License Agreement (the Lilly Agreement) with Eli Lilly and Company (Lilly) for the discovery, development and commercialization of AOC products directed against certain targets in immunology and other select indications on a worldwide basis. Under the Lilly Agreement, the Company granted Lilly an exclusive, worldwide, royalty-bearing license, with the right to sublicense (subject to certain conditions), under the Company’s technology to research, develop, manufacture and sell products containing AOCs that are directed to up to six mRNA targets. The Company retains the right to use its technology to perform its obligations under the Lilly Agreement and for all purposes not granted to Lilly. The Company agreed that it will not, itself or with a third party, research, develop, manufacture or commercialize or otherwise exploit any compound or product directed against targets subject to the Lilly Agreement. In consideration of the rights granted to Lilly under the Lilly Agreement, the Company received a one-time upfront fee of $20.0 million and is eligible to receive up The Company has identified multiple promises to deliver goods and services, which include at inception of the agreement: (i) a license to technology and patents, information and know-how; and (ii) collaboration, including research services, technical and regulatory support provided by the Company. At inception and through September 30, 2022, the Company has identified one performance obligation for all the deliverables under the Lilly Agreement since the delivered elements are either not capable of being distinct or are not distinct within the context of the contract. Accordingly, the Company will recognize revenue for the fixed or determinable collaboration in an amount proportional to the collaboration expenses incurred and the total estimated collaboration expenses five-year Collaboration receivables related to the Lilly Agreement were $1.3 million and $0.9 million as of September 30, 2022 and December 31, 2021, respectively, which are included in prepaid and other assets on the condensed balance sheets. A reconciliation of the closing balance of deferred revenue related to the Lilly Agreement is as follows (in thousands): Balance at December 31, 2021 $ 11,108 Revenue recognized (3,068 ) Balance at September 30, 2022 $ 8,040 Research Agreement with MyoKardia, Inc. In December 2020, the Company entered into a research collaboration (the MyoKardia Agreement) with MyoKardia, Inc. (MyoKardia),

Property and Equipment, Net

Property and Equipment, Net	9 Months Ended
Property and Equipment, Net	Sep. 30, 2022
Property Plant And Equipment [Abstract]
Property and Equipment, Net	6. Property and Equipment, net Property and equipment consist of the following (in thousands): September 30, 2022 December 31, 2021 Laboratory equipment $ 6,788 $ 4,775 Computers and software 116 116 Office furniture and equipment 1,623 1,398 Leasehold improvements 249 249 Property and equipment, gross 8,776 6,538 Less accumulated depreciation (2,739 ) (1,733 ) Total property and equipment, net $ 6,037 $ 4,805 Depreciation expense related to property and equipment was $0.4 million and $0.2 million for the three months ended September 30, 2022 and 2021, respectively, and $1.0 million and $0.4 million for the nine months ended September 30, 2022 and 2021, respectively.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Sep. 30, 2022
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	7. Commitments and Contingencies Lease Agreements The Company determines if an arrangement is a finance lease, operating lease or short-term lease at inception, or as applicable, and accounts for the arrangement under the relevant accounting literature. During the periods presented, the Company was party to various non-cancellable office and laboratory space operating leases and short-term leases. Under the relevant guidance, the Company recognizes operating lease right-of-use (ROU) assets and liabilities based on the present value of the future minimum lease payments over the lease term at the commencement date, using the Company’s assumed incremental borrowing rate, and amortizes the ROU assets and liabilities over the lease term. Lease expense for operating leases is recognized on a straight-line basis over the lease term. Short-term leases are not subject to recognition of an ROU asset or liability or straight-line lease expense requirements. As of September 30, 2022, future minimum payments for the Company’s operating lease liabilities are as follows (in thousands): Year ending December 31, 2022 (remaining) $ 767 2023 3,113 2024 3,207 2025 3,303 2026 3,111 Total lease payments 13,501 Less imputed interest (2,226 ) Total operating lease liabilities 11,275 Less lease liabilities, current portion (3,090 ) Lease liabilities, net of current portion $ 8,185 Supplemental cash flow information related to cash paid for amounts included in the measurement of operating lease liabilities was as follows (in thousands): Nine Months Ended September 30, 2022 2021 Cash paid included in operating cash flows $ 1,002 $ — Rent expense was as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2022 2021 2022 2021 Operating leases $ 689 $ 150 $ 2,068 $ 449 Short-term leases 26 78 26 159 Total rent expense $ 715 $ 228 $ 2,094 $ 608 Litigation Liabilities for loss contingencies arising from claims, assessments, litigation, fines, penalties and other sources are recorded when it is probable that a liability has been incurred and the amount can be reasonably estimated. There are no matters currently outstanding for which any liabilities have been accrued.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
Stockholders' Equity	Sep. 30, 2022
Equity [Abstract]
Stockholders' Equity	8. Stockholders’ Equity Amended and Restated Certificate of Incorporation On June 16, 2020, the Company’s certificate of incorporation was amended and restated to authorize 400,000,000 shares of common stock and 40,000,000 shares of undesignated preferred stock, each with a par value of $0.0001 per share. There was no preferred stock issued for any of the periods presented in the condensed financial statements. Common Stock On June 16, 2020, the Company completed its IPO in which it sold 16,560,000 shares of common stock at an offering price of $18.00 per share. Proceeds from the IPO, net of underwriting discounts, commissions and offering costs, were $274.1 million. On July 2, 2021, the Company entered into a sales agreement (the 2021 Sales Agreement) with Cowen and Company, LLC (the Sales Agent), under which the Company may, from time to time, sell shares of its common stock having an aggregate offering price of up to $150.0 million through the Sales Agent. Sales of the Company’s common stock made pursuant to the 2021 Sales Agreement are made under the Company’s shelf registration statement on Form S-3, which became automatically effective upon filing on July 2, 2021 (the Shelf Registration Statement). In addition, the 2021 Sales Agreement may be terminated by the Company or the Sales Agent at any time upon ten days’ notice to the other party, or by the Sales Agent, with respect to itself, at any time in certain circumstances, including the occurrence of a material adverse change. During the nine months ended September 30, 2022, the Company sold 6,361,212 shares of its common stock pursuant to the 2021 Sales Agreement and received net proceeds of $101.7 million, after deducting offering-related transaction costs and commissions. Through September 30, 2022, the Company has sold 7,141,761 shares of its common stock pursuant to the 2021 Sales Agreement and received net proceeds of $121.3 million, after deducting offering-related transaction costs and commissions. See Note 10 (Subsequent Events) for information on additional shares sold after September 30, 2022. On August 6, 2021, the Company completed a public offering of 9,200,000 shares of its common stock at a public offering price of $18.00 per share. The net proceeds from the offering were $155.1 million, after deducting underwriting discounts, commissions and offering costs. Equity Incentive Plans In January 2013, the Company adopted the 2013 Equity Incentive Plan (the 2013 Plan). The 2013 Plan provided for the issuance of incentive units to employees and nonemployees of the Company and non‑statutory unit options, restricted unit awards, unit appreciation rights, and unit bonuses to directors, employees and consultants of the Company. Under the 2013 Plan, 2,127,013 units were initially reserved for issuance. Upon the conversion of the Company to a C corporation, the 2013 Plan continued on the same terms and conditions. In 2019, the number of shares reserved under the 2013 Plan was increased to 4,771,615 shares. In June 2020, the Company’s board of directors adopted, and the Company’s stockholders approved, the 2020 Incentive Award Plan (the 2020 Plan), which became effective in connection with the IPO. Pursuant to the 2020 Plan, the Company ceased granting awards under the 2013 Plan. Under the 2020 Plan, the Company may grant stock options, restricted stock, dividend equivalents, restricted stock units, stock appreciation rights, and other stock or cash-based awards to individuals who are then employees, officers, non-employee directors or consultants of the Company. A total of 3,900,000 shares of common stock were initially reserved for issuance under the 2020 Plan. In addition, the number of shares of common stock available for issuance under the 2020 Plan will be increased annually on the first day of each fiscal year during the term of the 2020 Plan, beginning with the 2021 fiscal year, by an amount equal to the lesser of (a) 5% of the shares of common stock outstanding on the final day of the immediately preceding calendar year or (b) such smaller number of shares as determined by the Company’s board of directors. At September 30, 2022, 1,364,998 shares remain available for issuance under the 2020 Plan. Stock Options Options granted from the 2013 Plan and 2020 Plan are exercisable at various dates and will expire no more than ten years from their date of grant. Options generally vest over a four-year Stock option activity for employee and nonemployee awards and related information is as follows (in thousands, except per share data): Number of Options Weighted- Average Exercise Price Per Share Outstanding at December 31, 2021 5,778 $ 14.49 Granted 4,040 15.42 Exercised (282 ) 1.12 Forfeited/expired (443 ) 16.60 Outstanding at September 30, 2022 9,093 $ 15.22 The weighted-average grant date fair value of options granted during the nine months ended September 30, 2022 and 2021 were $11.08 and $16.83 per share, respectively. Employee Stock Purchase Plan In June 2020, the Company adopted the ESPP, which permits participants to contribute up to 15% of their eligible compensation during defined rolling six-month periods to purchase the Company’s common stock. The purchase price of the shares will be 85% of the lower of the fair market value of the Company’s common stock on the first day of trading of the offering period or on the applicable purchase date. The Company issued 48,760 and 14,235 shares of common stock under the ESPP during the nine months ended September 30, 2022 and 2021, respectively. The Company had an outstanding liability of $0.3 million at September 30, 2022, which is included in accounts payable and accrued liabilities on the condensed balance sheet, for employee contributions to the ESPP for shares pending issuance at the end of the offering period. As of September 30, 2022, 589,803 shares of common stock were available for issuance under the ESPP. Stock-Based Compensation Expense The assumptions used in the Black-Scholes model to determine the fair value of stock option grants and shares purchasable under the ESPP were as follows: Nine Months Ended September 30, Stock Option Grants 2022 2021 Risk-free interest rate 1.5% - 3.4% 0.5% - 1.2% Expected volatility 85% 87%-88% Expected term (in years) 5.5 - 6.1 5.5 - 6.1 Expected dividend yield —% —% Nine Months Ended September 30, ESPP 2022 2021 Risk-free interest rate 2.2% 0.1% Expected volatility 79% 75% Expected term (in years) 0.5 0.5 Expected dividend yield —% —% The allocation of stock-based compensation expense was as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2022 2021 2022 2021 Research and development expense $ 4,151 $ 2,433 $ 10,948 $ 6,930 General and administrative expense 2,935 2,117 8,884 5,610 Total stock-based compensation expense $ 7,086 $ 4,550 $ 19,832 $ 12,540 As of September 30, 2022, the unrecognized compensation cost related to outstanding time-based options was $68.3 million, which is expected to be recognized over a weighted-average period of 2.7 years. As of September 30, 2022, the unrecognized compensation cost related to stock purchase rights under the ESPP was $87.3 thousand, which is expected to be recognized over a weighted-average period of 0.2 years.

COVID-19

COVID-19	9 Months Ended
COVID-19	Sep. 30, 2022
Extraordinary And Unusual Items [Abstract]
COVID-19	9. COVID-19 The COVID-19 outbreak in the United States has caused significant business disruption. The extent of the impact of COVID-19 on the Company’s operational and financial performance will depend on certain developments, including the continued spread of COVID-19 and the measures taken by the governmental authorities, and its impact on the Company’s preclinical studies and clinical trials, employees and vendors, all of which are uncertain and cannot be predicted, particularly as the Company advances its product candidates into and through clinical development. In December 2021, the Company transitioned to a hybrid model with its employees generally working both remotely and onsite, and the Company anticipates it will continue to use this model going forward. To date, the Company has not experienced material disruptions in its business operations. However, a prolonged outbreak could have a material adverse impact on the financial results and business operations of the Company, including the timing and ability of the Company to complete certain clinical trials and other efforts required to advance the development of its product candidates and raise additional capital.

Subsequent Events

Subsequent Events	9 Months Ended
Subsequent Events	Sep. 30, 2022
Subsequent Events [Abstract]
Subsequent Events	10. Subsequent Events From October 1, 2022 through November 8, 2022, the Company sold 1,410,600 shares of its common stock pursuant to the 2021 Sales Agreement and received net proceeds of $19.4 million, after deducting offering-related transaction costs and commissions. On November 8, 2022, the Company entered into a sales agreement (the 2022 Sales Agreement) with the Sales Agent, with substantially similar terms as the 2021 Sales Agreement described in Note 8 (Stockholders’ Equity). Under the 2022 Sales Agreement, the Company may, from time to time, sell shares of its common stock having an aggregate offering price of up to $200.0 million through the Sales Agent. Sales of the shares of common stock, if any, will be made at prevailing market prices at the time of sale, or as otherwise agreed with the Sales Agent. The Company is not obligated to sell, and the Sales Agent is not obligated to buy or sell, any shares of common stock under the 2022 Sales Agreement. Upon entry into the 2022 Sales Agreement, the 2021 Sales Agreement was terminated.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Sep. 30, 2022
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited interim condensed financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) and the rules and regulations of the Securities and Exchange Commission (SEC) related to a quarterly report on Form 10-Q. Certain information and note disclosures normally included in annual financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to those rules and regulations. The unaudited interim condensed financial statements reflect all adjustments which, in the opinion of management, are necessary for a fair statement of the results for the periods presented. All such adjustments are of a normal and recurring nature. The operating results presented in these unaudited interim condensed financial statements are not necessarily indicative of the results that may be expected for any future periods. These unaudited interim condensed financial statements should be read in conjunction with the audited financial statements and the notes thereto for the year ended December 31, 2021 included in the Company’s annual report on Form 10-K filed with the SEC on March 1, 2022.
Use of Estimates	Use of Estimates The Company’s condensed financial statements accordance GAAP, which the Company and assumptions that impact the amounts of liabilities, revenues and expenses and the disclosure of contingent and liabilities in the condensed financial statements and accompanying notes. The most significant estimates in the Company’s condensed financial statements to Although these on the Company’s knowledge of events and actions undertake the actual ultimately these and assumptions.
Cash, Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted Cash The Company considers all highly liquid investments with original maturities of three months or less from the date of purchase to be cash equivalents. Cash and cash equivalents include cash in readily available checking and money market accounts. Restricted cash represents cash held as collateral for the letter of credit required under the Company’s facility lease and is reported as a long-term asset in the accompanying condensed balance sheets.
Marketable Securities	Marketable Securities The Company’s marketable securities primarily consist of U.S. Government and corporate debt securities. The Company classifies its marketable securities as available-for-sale and records such assets at estimated fair value in the condensed balance sheets, with unrealized gains and losses, if any, reported as a component of other comprehensive income (loss) within the condensed statements of operations and comprehensive loss and as a separate component of stockholders’ equity. The Company classifies marketable securities with remaining maturities greater than one year as current assets because such marketable securities are available to fund the Company’s current operations. Realized gains and losses are calculated on the specific identification method and recorded as interest income. There were no realized gains and losses during any of the periods presented. At each balance sheet date, the Company assesses available-for-sale securities in an unrealized loss position to determine whether the unrealized loss is other-than-temporary. When the Company determines that a decline in the fair value below its cost basis is other-than-temporary, the Company recognizes an impairment loss in the period in which the other-than-temporary decline occurred. There have been no other-than-temporary impairments recognized during any of the periods presented. See Note 4 (Marketable Securities) for further information.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash, cash equivalents and marketable securities. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company has not experienced any losses in such accounts and believes it is not exposed to significant risk on its cash balances due to the financial position of the depository institutions in which those deposits are held. Additionally, the Company has established guidelines regarding approved investments, credit quality, diversification, liquidity and maturities of investments, which are designed to maintain safety and liquidity.
Fair Value of Financial Instruments	Fair Value of Financial Instruments Certain assets and liabilities are carried at fair value under GAAP. Fair value is defined as 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, 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 and that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. The asset’s or liability’s fair value measurement level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. None of the Company’s non-financial assets are recorded at fair value on a non-recurring basis. The carrying amounts reflected in the Company’s condensed balance sheets for prepaid and other assets and accounts payable and accrued liabilities approximate their fair values due to their short-term nature. See Note 3 (Fair Value Measurements) for information on assets measured at fair value.
Property and Equipment, Net	Property and Equipment, net Property and equipment, including leasehold improvements, are stated at cost less accumulated depreciation and amortization. Depreciation and amortization are recorded using the straight-line method over the estimated useful lives of the related assets, which ranges from three to five years. Leasehold improvements are amortized on a straight-line basis over the shorter of the estimated useful lives of the assets or the remaining lease term. Repairs and maintenance charges that do not increase the useful life of the assets are charged to operating expenses as incurred.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets Long-lived assets consist of property and equipment. An impairment loss is recorded if and when events and circumstances indicate that assets might be impaired and the undiscounted cash flows estimated to be generated by those assets are less than the carrying amount of those assets. The Company has not recognized any impairment losses in any of the periods presented in these condensed financial statements.
Segment Information	Segment Information Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by management in making decisions regarding resource allocation and assessing performance. The Company manages its operations as a single
Revenue Recognition	Revenue Recognition To date, all the Company’s revenue has been derived from collaboration and research agreements. The terms of these arrangements include the following types of payments to the Company: non-refundable, upfront license fees; development, regulatory and commercial milestone payments; payments for research and development services provided by the Company or for manufacturing supply services the Company provides through its contract manufacturers; and royalties on net sales of licensed products. The Company performs the following steps in determining the appropriate amount of revenue to be recognized as it fulfills its obligations under each of these agreements: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations, including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (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 receives payments from its collaborators based on billing schedules established in each contract. Upfront and other payments may require deferral of revenue recognition to a future period until the Company performs its obligations under its research and collaboration arrangements. Amounts are recorded as accounts receivable when the Company’s right to consideration is unconditional. See Note 5 (Collaboration, License and Research Agreements) for further information.
Research and Development Costs	Research and Development Costs Research and development costs are expensed as incurred and include salaries, benefits and stock-based compensation associated with research and development personnel, third-party research and development expenses, license fees, laboratory supplies, facilities, overhead costs, and consultants. Nonrefundable advance payments for goods and services that will be used in future research and development activities are capitalized and recorded as expense in the period that the Company receives the goods or when services are performed. Upfront and milestone payments to acquire contractual rights to licensed technology are expensed when incurred if there is uncertainty in the Company receiving future economic benefit from the acquired contractual rights. Certain of these contractual rights may require the Company to make additional milestone payments upon initiation of a pivotal trial and the U.S. Food and Drug Administration approval, which are not expected to exceed $8.5 million.
Patent Costs	Patent Costs Costs related to filing and pursuing patent applications are recorded as general and administrative expense and expensed as incurred since recoverability of such expenditures is uncertain.
Income Taxes	Income Taxes The Company accounts for income taxes in accordance with Accounting Standards Codification (ASC) 740, Income Taxes When uncertain tax positions exist, the Company recognizes the tax benefit of tax positions to the extent that the benefit would more likely than not be realized assuming examination by the taxing authority. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position as well as consideration of the available facts and circumstances. The Company is subject to taxation in the United States and various state jurisdictions. As of December 31, 2021, the Company’s tax years since conversion to a corporation in 2019 are subject to examination by taxing authorities.
Stock-Based Compensation	Stock-Based Compensation Stock-based compensation expense for employee and non-employee stock option grants is recorded at the estimated fair value of the award as of the grant date and is recognized as expense on a straight-line basis over the requisite service period (usually the vesting period) of the stock-based award, and forfeitures are recognized as incurred. Stock-based compensation expense for employee stock purchases under the Company’s Employee Stock Purchase Plan (the ESPP) is recorded at the estimated fair value of the purchase as of the plan enrollment date and is recognized as expense on a straight-line basis over the applicable six-month ESPP offering period. The estimation of fair value for stock-based compensation requires management to make estimates and judgments about, among other things, the estimated life of options and volatility of the Company’s common stock. The judgments directly affect the amount of compensation expense that will be recognized.
Comprehensive Loss	Comprehensive Loss Comprehensive loss is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources, including unrealized gains and losses on marketable securities. Comprehensive gains (losses) have been reflected in the statements of operations and comprehensive loss for all periods presented.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is computed by dividing the net loss by the weighted-average number of common shares outstanding for the period, adjusted for the weighted-average number of common shares outstanding that are subject to repurchase or forfeiture. The Company has excluded 8,936 and 22,158 weighted-average shares subject to repurchase or forfeiture from the weighted-average number of common shares outstanding for the three months ended September 30, 2022 and 2021, respectively, and 11,435 and 39,345 weighted-average shares subject to repurchase or forfeiture from the weighted-average number of common shares outstanding for the nine months ended September 30, 2022 and 2021, respectively. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of common shares and dilutive common stock equivalents outstanding for the period determined using the treasury-stock and if-converted methods. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding as inclusion of the potentially dilutive securities would be anti-dilutive. Potentially dilutive securities not included in the calculation of diluted net loss per share, because to do so would be anti-dilutive, are as follows (in common stock equivalent shares; in thousands): September 30, 2022 2021 Common stock options issued and outstanding 9,093 5,649 Common stock subject to repurchase or forfeiture 8 18 ESPP shares pending issuance 27 12 Total 9,128 5,679
Recently Issued Accounting Pronouncements and Accounting Standards Not Yet Adopted	Recently Issued Accounting Pronouncements From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies that are adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on its financial position or results of operations upon adoption. Accounting Standards Not Yet Adopted In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses: Measurement of Credit Losses on Financial Statements (Topic 326), which intends to improve financial reporting by requiring earlier recognition of credit losses on certain financial assets, such as available-for-sale debt securities. Subsequent to the issuance of ASU 2016-13, the FASB issued several additional Accounting Standard Updates (ASUs) to clarify implementation guidance, provide narrow-scope improvements and provide additional disclosure guidance. In November 2019, the FASB issued an amendment making this ASU effective for fiscal years beginning after December 15, 2022 for smaller reporting companies. The Company was a smaller reporting company at the determination date, and therefore the new standard will be effective for the Company on January 1, 2023. The Company is currently evaluating the potential impact that the adoption of ASU 2016-13 may have on its financial statements and related disclosures.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	9 Months Ended
Summary of Significant Accounting Policies (Tables)	Sep. 30, 2022
Accounting Policies [Abstract]
Schedule of Potentially Dilutive Securities not Included in Calculation of Diluted Net Loss Per Share	Potentially dilutive securities not included in the calculation of diluted net loss per share, because to do so would be anti-dilutive, are as follows (in common stock equivalent shares; in thousands): September 30, 2022 2021 Common stock options issued and outstanding 9,093 5,649 Common stock subject to repurchase or forfeiture 8 18 ESPP shares pending issuance 27 12 Total 9,128 5,679

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
Fair Value Measurements (Tables)	Sep. 30, 2022
Fair Value Disclosures [Abstract]
Summary of Cash Equivalents and Marketable Securities Measured at Fair Value	The following tables summarize the Company’s marketable securities measured at fair value (in thousands): Fair Value Measurements Using As of September 30, 2022 Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Marketable securities: U.S. Treasury securities $ 236,553 $ 236,553 $ — $ — U.S. Government agency securities 4,927 — 4,927 — Negotiable certificates of deposit 3,340 — 3,340 — Corporate debt securities 17,029 — 17,029 — Total $ 261,849 $ 236,553 $ 25,296 $ — Fair Value Measurements Using As of December 31, 2021 Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Marketable securities: U.S. Treasury securities $ 65,372 $ 65,372 $ — $ — Negotiable certificates of deposit 3,873 — 3,873 — Corporate debt securities 15,850 — 15,850 — Total $ 85,095 $ 65,372 $ 19,723 $ —

Marketable Securities (Tables)

Marketable Securities (Tables)	9 Months Ended
Marketable Securities (Tables)	Sep. 30, 2022
Investments Debt And Equity Securities [Abstract]
Summary of Marketable Securities	The Company’s marketable securities, which consist of highly liquid marketable debt securities, are classified as available-for-sale and are stated at fair value. The following tables summarize the Company’s marketable securities (in thousands): As of September 30, 2022 Maturity (in years) Amortized Cost Unrealized Gains Unrealized Losses Estimated Fair Value U.S. Treasury securities 1 or less $ 197,652 $ — $ (1,938 ) $ 195,714 U.S. Government agency securities 1 or less 5,000 — (73 ) 4,927 Negotiable certificates of deposit 1 or less 2,683 — (48 ) 2,635 Corporate debt securities 1 or less 16,131 — (344 ) 15,787 U.S. Treasury securities 1 - 2 41,823 — (984 ) 40,839 Negotiable certificates of deposit 1 - 2 734 — (29 ) 705 Corporate debt securities 1 - 2 1,289 — (47 ) 1,242 Total $ 265,312 $ — $ (3,463 ) $ 261,849 As of December 31, 2021 Maturity (in years) Amortized Cost Unrealized Gains Unrealized Losses Estimated Fair Value U.S. Treasury securities 1 or less $ 2,492 $ — $ (1 ) $ 2,491 Negotiable certificates of deposit 1 or less 1,190 — (1 ) 1,189 U.S. Treasury securities 1 - 2 63,034 — (153 ) 62,881 Negotiable certificates of deposit 1 - 2 2,687 — (3 ) 2,684 Corporate debt securities 1 - 2 15,879 — (29 ) 15,850 Total $ 85,282 $ — $ (187 ) $ 85,095

Collaboration, License and Re_2

Collaboration, License and Research Agreements (Tables)	9 Months Ended
Collaboration, License and Research Agreements (Tables)	Sep. 30, 2022
Collaboration License And Research Agreements [Abstract]
Summary of Reconciliation of Deferred Revenue Related to Lilly Agreement	A reconciliation of the closing balance of deferred revenue related to the Lilly Agreement is as follows (in thousands): Balance at December 31, 2021 $ 11,108 Revenue recognized (3,068 ) Balance at September 30, 2022 $ 8,040

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	9 Months Ended
Property and Equipment, Net (Tables)	Sep. 30, 2022
Property Plant And Equipment [Abstract]
Schedule of Property and Equipment	Property and equipment consist of the following (in thousands): September 30, 2022 December 31, 2021 Laboratory equipment $ 6,788 $ 4,775 Computers and software 116 116 Office furniture and equipment 1,623 1,398 Leasehold improvements 249 249 Property and equipment, gross 8,776 6,538 Less accumulated depreciation (2,739 ) (1,733 ) Total property and equipment, net $ 6,037 $ 4,805

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
Commitments and Contingencies (Tables)	Sep. 30, 2022
Commitments And Contingencies Disclosure [Abstract]
Schedule of Future Minimum Payments for Operating Lease Liabilities	As of September 30, 2022, future minimum payments for the Company’s operating lease liabilities are as follows (in thousands): Year ending December 31, 2022 (remaining) $ 767 2023 3,113 2024 3,207 2025 3,303 2026 3,111 Total lease payments 13,501 Less imputed interest (2,226 ) Total operating lease liabilities 11,275 Less lease liabilities, current portion (3,090 ) Lease liabilities, net of current portion $ 8,185
Supplemental Cash Flow Information Related to Cash Paid for Amounts Included in Measurement of Operating Lease Liabilities	Supplemental cash flow information related to cash paid for amounts included in the measurement of operating lease liabilities was as follows (in thousands): Nine Months Ended September 30, 2022 2021 Cash paid included in operating cash flows $ 1,002 $ —
Schedule of Rent Expense	Rent expense was as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2022 2021 2022 2021 Operating leases $ 689 $ 150 $ 2,068 $ 449 Short-term leases 26 78 26 159 Total rent expense $ 715 $ 228 $ 2,094 $ 608

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
Stockholders' Equity (Tables)	Sep. 30, 2022
Equity [Abstract]
Summary of Stock Option Activity	Stock option activity for employee and nonemployee awards and related information is as follows (in thousands, except per share data): Number of Options Weighted- Average Exercise Price Per Share Outstanding at December 31, 2021 5,778 $ 14.49 Granted 4,040 15.42 Exercised (282 ) 1.12 Forfeited/expired (443 ) 16.60 Outstanding at September 30, 2022 9,093 $ 15.22
Schedule of Assumptions Used in Black-Scholes Model Pricing Model to to Determine Fair Value of Stock Option and Shares Purchasable Under ESPP	The assumptions used in the Black-Scholes model to determine the fair value of stock option grants and shares purchasable under the ESPP were as follows: Nine Months Ended September 30, Stock Option Grants 2022 2021 Risk-free interest rate 1.5% - 3.4% 0.5% - 1.2% Expected volatility 85% 87%-88% Expected term (in years) 5.5 - 6.1 5.5 - 6.1 Expected dividend yield —% —% Nine Months Ended September 30, ESPP 2022 2021 Risk-free interest rate 2.2% 0.1% Expected volatility 79% 75% Expected term (in years) 0.5 0.5 Expected dividend yield —% —%
Schedule of Allocated Stock-based Compensation Expense	The allocation of stock-based compensation expense was as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2022 2021 2022 2021 Research and development expense $ 4,151 $ 2,433 $ 10,948 $ 6,930 General and administrative expense 2,935 2,117 8,884 5,610 Total stock-based compensation expense $ 7,086 $ 4,550 $ 19,832 $ 12,540

Description of Business and B_2

Description of Business and Basis of Presentation - Additional Information (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Accounting Policies [Abstract]
Accumulated deficit	$ 308,073	$ 184,549
Cash, cash equivalents and marketable securities	$ 405,500

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2022 USD ($) shares	Sep. 30, 2021 shares	Sep. 30, 2022 USD ($) Segment shares	Sep. 30, 2021 shares
Summary Of Significant Accounting Policies [Line Items]
Realized gains and losses on marketable securities			$ 0
Other-than-temporary impairments on marketable securities			0
Transfers of assets measured on recurring basis out of Level 1 into Level 2	$ 0		0
Transfers of assets measured on recurring basis out of Level 2 into Level 1	0		0
Transfers of liabilities measured on recurring basis out of Level 1 into Level 2	0		0
Transfers of liabilities measured on recurring basis out of Level 2 into Level 1	$ 0		0
Transfers of financial instrument classified as liability into level 3			0
Transfers of financial instrument classified as liability out of level 3			0
Transfers of financial instrument classified as asset into level 3			0
Transfers of financial instrument classified as asset out of level 3			$ 0
Number of operating segment \| Segment			1
Maximum milestone payment to acquire contractual rights			$ 8,500,000
Weighted-average shares/units subject to repurchase or forfeiture \| shares	8,936	22,158	11,435	39,345
Minimum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets			3 years
Maximum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets			5 years

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Schedule of Potentially Dilutive Securities not Included in Calculation of Diluted Net Loss Per Share (Details) - shares shares in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	9,128	5,679
Common Stock Options Issued and Outstanding
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	9,093	5,649
Common Stock Subject to Repurchase or Forfeiture
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	8	18
ESPP Shares Pending Issuance
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	27	12

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Cash Equivalents and Marketable Securities Measured at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	$ 261,849	$ 85,095
Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	261,849	85,095
Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	236,553	65,372
Recurring \| Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	25,296	19,723
Recurring \| Significant Unobservable Inputs (Level 3)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	0	0
Recurring \| US Treasury Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	236,553	65,372
Recurring \| US Treasury Securities \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	236,553	65,372
Recurring \| US Treasury Securities \| Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	0	0
Recurring \| US Treasury Securities \| Significant Unobservable Inputs (Level 3)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	0	0
Recurring \| Corporate debt securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	17,029	15,850
Recurring \| Corporate debt securities \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	0	0
Recurring \| Corporate debt securities \| Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	17,029	15,850
Recurring \| Corporate debt securities \| Significant Unobservable Inputs (Level 3)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	0	0
Recurring \| U.S. Government Agency Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	4,927	0
Recurring \| U.S. Government Agency Securities \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	0	0
Recurring \| U.S. Government Agency Securities \| Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	4,927	0
Recurring \| U.S. Government Agency Securities \| Significant Unobservable Inputs (Level 3)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	0	0
Recurring \| Certificates of Deposit
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	3,340	3,873
Recurring \| Certificates of Deposit \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	0	0
Recurring \| Certificates of Deposit \| Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	3,340	3,873
Recurring \| Certificates of Deposit \| Significant Unobservable Inputs (Level 3)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Marketable securities	$ 0	$ 0

Marketable Securities - Summary

Marketable Securities - Summary of Marketable Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 265,312	$ 85,282
Unrealized Gains	0	0
Unrealized Losses	(3,463)	(187)
Estimated Fair Value	261,849	85,095
U.S. Treasury Securities with 1 Year or Less Maturity
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	197,652	2,492
Unrealized Gains	0	0
Unrealized Losses	(1,938)	(1)
Estimated Fair Value	195,714	2,491
Corporate Debt Securities with 1 to 2 Years Maturity
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	1,289	15,879
Unrealized Gains	0	0
Unrealized Losses	(47)	(29)
Estimated Fair Value	1,242	15,850
U.S. Government Agency Securities with 1 Year or Less Maturity
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	5,000
Unrealized Gains	0
Unrealized Losses	(73)
Estimated Fair Value	4,927
Negotiable Certificates of Deposit with 1 Year or Less Maturity
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	2,683	1,190
Unrealized Gains	0	0
Unrealized Losses	(48)	(1)
Estimated Fair Value	2,635	1,189
U.S. Treasury Securities with 1 to 2 Years Maturity
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	41,823	63,034
Unrealized Gains	0	0
Unrealized Losses	(984)	(153)
Estimated Fair Value	40,839	62,881
Corporate Debt Securities with 1 Year or Less Maturity
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	16,131
Unrealized Gains	0
Unrealized Losses	(344)
Estimated Fair Value	15,787
Negotiable Certificates of Deposit with 1 to 2 Years Maturity
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	734	2,687
Unrealized Gains	0	0
Unrealized Losses	(29)	(3)
Estimated Fair Value	$ 705	$ 2,684

Marketable Securities - Additio

Marketable Securities - Additional Information (Details) - USD ($)	Sep. 30, 2022	Dec. 31, 2021
Investments Debt And Equity Securities [Abstract]
Unrealized losses on marketable securities	$ 3,463,000	$ 187,000
Unrealized losses position for 12 month or greater	$ 0

Collaboration, License and Re_3

Collaboration, License and Research Agreements - Additional Information (Details)	1 Months Ended	3 Months Ended		9 Months Ended
	Apr. 30, 2019 USD ($) Product	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($) Obligation	Sep. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue recognized		$ 2,482,000	$ 2,163,000	$ 6,455,000	$ 7,474,000
Research Collaboration and License Agreement with Eli Lilly
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront fees received	$ 20,000,000
License agreement expiry period	10 years
Number of performance obligation \| Obligation				1
Period for expects performance obligation				5 years
Revenue recognized		2,400,000	2,100,000	$ 6,300,000	7,300,000
Deferred revenue		8,040,000		8,040,000		$ 11,108,000
Research Collaboration and License Agreement with Eli Lilly \| Prepaid and Other Assets
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration receivables		1,300,000		1,300,000		$ 900,000
Research Collaboration and License Agreement with Eli Lilly \| Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Rights to antibody oligonucleotide conjugates for messengers RNA targets. \| Product	6
Development milestone payment eligible to receive per target	$ 60,000,000
Regulatory milestone payment eligible to receive per target	140,000,000
Commercialization milestone payment eligible to receive	$ 205,000,000
Research Collaboration with MyoKardia, Inc.
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue recognized		$ 36,700	$ 200,000	$ 200,000	$ 200,000

Collaboration, License and Re_4

Collaboration, License and Research Agreements - Reconciliation of Deferred Revenue Related to Lilly Agreement (Details) - Research Collaboration and License Agreement with Eli Lilly $ in Thousands	9 Months Ended
	Sep. 30, 2022 USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Balance	$ 11,108
Revenue recognized	(3,068)
Balance	$ 8,040

Property and Equipment, Net - S

Property and Equipment, Net - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 8,776	$ 6,538
Less accumulated depreciation	(2,739)	(1,733)
Total property and equipment, net	6,037	4,805
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	6,788	4,775
Computers and Software
Property Plant And Equipment [Line Items]
Property and equipment, gross	116	116
Office Furniture and Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	1,623	1,398
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 249	$ 249

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Property Plant And Equipment [Abstract]
Depreciation expenses related to property and equipment	$ 400	$ 200	$ 1,006	$ 431

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details)	9 Months Ended
	Sep. 30, 2022 USD ($)
Commitments And Contingencies Disclosure [Abstract]
Operating lease, description	During the periods presented, the Company was party to various non-cancellable office and laboratory space operating leases and short-term leases. Under the relevant guidance, the Company recognizes operating lease right-of-use (ROU) assets and liabilities based on the present value of the future minimum lease payments over the lease term at the commencement date, using the Company’s assumed incremental borrowing rate, and amortizes the ROU assets and liabilities over the lease term. Lease expense for operating leases is recognized on a straight-line basis over the lease term. Short-term leases are not subject to recognition of an ROU asset or liability or straight-line lease expense requirements.
Loss contingencies accrued	$ 0

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Future Minimum Payments For Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
2022 (remaining)	$ 767
2023	3,113
2024	3,207
2025	3,303
2026	3,111
Total lease payments	13,501
Less imputed interest	(2,226)
Total operating lease liabilities	11,275
Less lease liabilities, current portion	(3,090)	$ (1,769)
Lease liabilities, net of current portion	$ 8,185	$ 9,960

Commitments and Contingencies_3

Commitments and Contingencies - Supplemental Cash Flow Information Related to Cash Paid for Amounts Included in Measurement of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Commitments And Contingencies Disclosure [Abstract]
Cash paid included in operating cash flows	$ 1,002	$ 0

Commitments and Contingencies_4

Commitments and Contingencies - Schedule of Rent Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Commitments And Contingencies Disclosure [Abstract]
Operating leases	$ 689	$ 150	$ 2,068	$ 449
Short-term leases	26	78	26	159
Total rent expense	$ 715	$ 228	$ 2,094	$ 608

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($)

1 Months Ended

3 Months Ended

9 Months Ended

15 Months Ended

Aug. 06, 2021

Jul. 02, 2021

Jun. 16, 2020

Jun. 30, 2020

Jun. 30, 2022

Jun. 30, 2021

Sep. 30, 2022

Sep. 30, 2021

Sep. 30, 2022

Dec. 31, 2021

Dec. 31, 2019

Jan. 31, 2013

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

Common stock shares authorized

400,000,000

Preferred stock undesignated shares authorized

40,000,000

Common stock par value per share

$ 0.0001

Preferred stock par value per share

$ 0.0001

Preferred stock issued

Weighted-average grant date fair value of options granted

$ 11.08

$ 16.83

Time-based Options

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

Unrecognized compensation cost

$ 68,300,000

Weighted-average period of unrecognized compensation cost

2 years 8 months 12 days

Maximum

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

Award vesting period

4 years

2013 Equity Incentive Plan

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

Units initially reserved for issuance

2,127,013

Increased to number of shares reserved under plan

4,771,615

2013 Equity Incentive Plan | Maximum

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

Expiration period

10 years

2020 Incentive Award Plan

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

Shares of common stock initially reserved for issuance

3,900,000

Percentage of shares of common stock outstanding on final day of immediately preceding calendar year

Number of remaining shares available for issuance

1,364,998

2020 Incentive Award Plan | Maximum

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

Expiration period

10 years

Employee Stock Purchase Plan

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

Participant maximum contribution as percentage of eligible compensation

15%

Percentage of purchase price of shares of lower of fair market value

85%

Shares of common stock available for issuance

589,803

Shares issued under ESPP

48,760

14,235

Unrecognized compensation cost

$ 87,300

Weighted-average period of unrecognized compensation cost

2 months 12 days

Employee Stock Purchase Plan | Accounts Payable and Accrued Liabilities

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

Outstanding liability

$ 300,000

Common Stock

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

Shares issued under ESPP

49,000

14,000

2021 Sales Agreement

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

Sale of stock number of shares issued in transaction

6,361,212

7,141,761

Sale of common stock maximum aggregate offering price

$ 150,000,000

Termination notice period for sales agreement

10 days

Net proceeds from Issuance of common stock after deducting offering-related transaction costs and commissions

$ 101,700,000

$ 121,300,000

Public Offering

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

Sale of stock number of shares issued in transaction

16,560,000

Sale of stock, price per share

$ 18

Proceeds from the IPO, net of underwriting discounts, commissions and offering costs

$ 274,100,000

Follow-on Public Offering | Common Stock

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

Sale of stock number of shares issued in transaction

9,200,000

Sale of stock, price per share

$ 18

Proceeds from the follow-on public offering, net of underwriting discounts, commissions and offering costs

$ 155,100,000

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Stock Option Activity (Details) shares in Thousands	9 Months Ended
	Sep. 30, 2022 $ / shares shares
Number of Options
Outstanding at December 31, 2021 \| shares	5,778
Granted \| shares	4,040
Exercised \| shares	(282)
Forfeited/expired \| shares	(443)
Outstanding at September 30, 2022 \| shares	9,093
Weighted-Average Exercise Price
Outstanding at December 31, 2021 \| $ / shares	$ 14.49
Granted \| $ / shares	15.42
Exercised \| $ / shares	1.12
Forfeited/expired \| $ / shares	16.60
Outstanding at September 30, 2022 \| $ / shares	$ 15.22

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Assumptions Used in Black-Scholes Model Pricing Model to to Determine Fair Value of Stock Option and Shares Purchasable Under ESPP (Details)	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate, Minimum	1.50%	0.50%
Risk-free interest rate, Maximum	3.40%	1.20%
Expected volatility	85%
Expected dividend yield	0%	0%
Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate	2.20%	0.10%
Expected volatility	79%	75%
Expected term (in years)	6 months	6 months
Expected dividend yield	0%	0%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility		87%
Expected term (in years)	5 years 6 months	5 years 6 months
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility		88%
Expected term (in years)	6 years 1 month 6 days	6 years 1 month 6 days

Stockholders' Equity - Schedu_2

Stockholders' Equity - Schedule of Allocated Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 7,086	$ 4,550	$ 19,832	$ 12,540
Research and Development Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	4,151	2,433	10,948	6,930
General and Administrative Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 2,935	$ 2,117	$ 8,884	$ 5,610

Subsequent Events - Additional

Subsequent Events - Additional Information (Details) - USD ($) $ in Millions		1 Months Ended	9 Months Ended	15 Months Ended
	Jul. 02, 2021	Nov. 08, 2022	Sep. 30, 2022	Sep. 30, 2022
2021 Sales Agreement
Subsequent Event [Line Items]
Sale of stock number of shares issued in transaction			6,361,212	7,141,761
Net proceeds from Issuance of common stock after deducting offering-related transaction costs and commissions			$ 101.7	$ 121.3
Sale of common stock maximum aggregate offering price	$ 150
Subsequent Event \| 2021 Sales Agreement
Subsequent Event [Line Items]
Sale of stock number of shares issued in transaction		1,410,600
Net proceeds from Issuance of common stock after deducting offering-related transaction costs and commissions		$ 19.4
Subsequent Event \| 2022 Sales Agreement
Subsequent Event [Line Items]
Sale of common stock maximum aggregate offering price		$ 200