Acumen Pharmaceuticals (ABOS) 10-Q 15 Nov 21 2021 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2021	Nov. 15, 2021
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Entity Registrant Name	Acumen Pharmaceuticals, Inc.
Entity Central Index Key	0001576885
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-40551
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	36-4108129
Entity Address, Address Line One	427 Park St.
Entity Address, City or Town	Charlottesville
Entity Address, State or Province	VA
Entity Address, Postal Zip Code	22902
City Area Code	434
Local Phone Number	297-1000
Title of 12(b) Security	Common stock, par value $0.0001 per share
Trading Symbol	ABOS
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		40,470,323

Condensed Balance Sheets

Condensed Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 135,802	$ 43,777
Marketable securities, short-term	64,162
Grant receivable	109	109
Prepaid expenses and other current assets	4,840	543
Total current assets	204,913	44,429
Marketable securities, long-term	29,910
Property and equipment, net	13
Other assets	13
Total assets	234,849	44,429
Current liabilities
Accounts payable	382	531
Accrued expenses and other current liabilities	1,107	423
Preferred stock tranche rights liability		5,033
Preferred stock warrant liability		380
Total liabilities	1,489	6,367
Convertible Preferred Stock, Issued		56,653
Stockholders' deficit
Preferred stock, $0.0001 par value; 10,000,000 shares authorized and no shares issued and outstanding as of September 30, 2021; no shares authorized, issued and outstanding as of December 31, 2020
Common stock, $0.0001 par value; 300,000,000 shares authorized and 40,470,323 shares issued and outstanding as of September 30, 2021; 50,500,000 shares authorized and 419,124 shares issued and outstanding as of December 31, 2020	4
Additional paid-in capital	352,606	8,374
Accumulated deficit	(119,222)	(26,965)
Accumulated other comprehensive loss	(28)
Total stockholders' equity (deficit)	233,360	(18,591)
Total liabilities, convertible preferred stock and stockholders' equity (deficit)	234,849	44,429
Series A Convertible Preferred Stock [Member]
Current liabilities
Convertible Preferred Stock, Issued		1,067
Stockholders' deficit
Total stockholders' equity (deficit)	0	1,067
Series A-1 Convertible Preferred Stock [Member]
Current liabilities
Convertible Preferred Stock, Issued		16,333
Stockholders' deficit
Total stockholders' equity (deficit)	0	16,333
Series B Convertible Preferred Stock [Member]
Current liabilities
Convertible Preferred Stock, Issued		39,253
Stockholders' deficit
Total stockholders' equity (deficit)	$ 0	$ 39,253

Condensed Balance Sheets (Paren

Condensed Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Convertible Preferred Stock Shares Authorized		42,066,830
Convertible Preferred Stock Shares Issued		19,877,219
Convertible Preferred Stock Shares Outstanding		19,877,219
Convertible Preferred Stock, Liquidation Preference		$ 62,984
Preferred stock, par or stated value per share	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	0
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Common Stock Par Value	$ 0.0001	$ 0.0001
Common Shares Authorized	300,000,000	50,500,000
Common Shares Issued	40,470,323	419,124
Common Shares Outstanding	40,470,323	419,124
Series A Convertible Preferred Stock [Member]
Convertible Preferred Stock Par Value	$ 0.0001	$ 0.0001
Convertible Preferred Stock Shares Authorized	0	711,203
Convertible Preferred Stock Shares Issued	0	477,297
Convertible Preferred Stock Shares Outstanding	0	477,297
Convertible Preferred Stock, Liquidation Preference		$ 1,067
Series A-1 Convertible Preferred Stock [Member]
Convertible Preferred Stock Par Value	$ 0.0001	$ 0.0001
Convertible Preferred Stock Shares Authorized	0	11,898,177
Convertible Preferred Stock Shares Issued	0	7,537,879
Convertible Preferred Stock Shares Outstanding	0	7,537,879
Convertible Preferred Stock, Liquidation Preference		$ 16,847
Series B Convertible Preferred Stock [Member]
Convertible Preferred Stock Par Value	$ 0.0001	$ 0.0001
Convertible Preferred Stock Shares Authorized	0	29,457,450
Convertible Preferred Stock Shares Issued	0	11,862,043
Convertible Preferred Stock Shares Outstanding	0	11,862,043
Convertible Preferred Stock, Liquidation Preference		$ 45,070

Condensed Statements of Operati

Condensed Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Grant and other revenue		$ 730		$ 1,107
Operating expenses
Research and development	$ 1,800	2,994	$ 6,632	6,971
General and administrative	2,135	226	4,537	707
Total operating expenses	3,935	3,220	11,169	7,678
Loss from operations	(3,935)	(2,490)	(11,169)	(6,571)
Other income (expense)
Change in fair value of preferred stock tranche rights liability and preferred stock warrant liability			(81,157)
Interest income	37		45	1
Interest expense	(23)		(23)
Other income	19		47
Total other income (expense)	33		(81,088)	1
Net loss	(3,902)	(2,490)	(92,257)	(6,570)
Other comprehensive loss
Unrealized loss on marketable securities	(28)		(28)
Comprehensive loss	$ (3,930)	$ (2,490)	$ (92,285)	$ (6,570)
Net loss per common share, basic and diluted	$ (0.10)	$ (5.94)	$ (7)	$ (15.68)
Weighted-average shares outstanding, basic and diluted	38,266,593	419,124	13,177,983	419,124

Condensed Statements of Changes

Condensed Statements of Changes in Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Series A Convertible Preferred Stock [Member]	Series A-1 Convertible Preferred Stock [Member]	Series B Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss
Opening balance at Dec. 31, 2019	$ (11,420)	$ 1,067	$ 16,333			$ 8,220	$ (19,640)
Opening balance (Shares) at Dec. 31, 2019		477,297	7,537,879		419,124
Share-based compensation	116					116
Net loss	(6,570)						(6,570)
Closing balance at Sep. 30, 2020	(17,874)	$ 1,067	$ 16,333			8,336	(26,210)
Closing balance (Shares) at Sep. 30, 2020		477,297	7,537,879		419,124
Opening balance at Jun. 30, 2020	(15,423)	$ 1,067	$ 16,333			8,297	(23,720)
Opening balance (Shares) at Jun. 30, 2020		477,297	7,537,879		419,124
Share-based compensation	39					39
Net loss	(2,490)						(2,490)
Closing balance at Sep. 30, 2020	(17,874)	$ 1,067	$ 16,333			8,336	(26,210)
Closing balance (Shares) at Sep. 30, 2020		477,297	7,537,879		419,124
Opening balance at Dec. 31, 2020	(18,591)	$ 1,067	$ 16,333	$ 39,253		8,374	(26,965)
Opening balance (Shares) at Dec. 31, 2020		477,297	7,537,879	11,862,043	419,124
Issuance of milestone shares for cash, net of issuance costs				$ 30,031
Issuance of milestone shares for cash, net of issuance costs (Shares)				7,908,027
Exercise of preferred stock warrant			$ 1,250
Exercise of preferred stock warrant (shares)			447,426
Reclassification of preferred stock tranche rights liability upon issuance of milestone shares				$ 81,190
Reclassification of warrant liability upon exercise of preferred stock warrant	5,380		$ 5,380
Exercise of common stock warrants	614					614
Exercise of common stock warrants (Shares)					137,446
Conversion of convertible preferred stock into common stock upon initial public offering	174,504	$ (1,067)	$ (22,963)	$ (150,474)	$ 3	174,501
Conversion of convertible preferred stock into common stock upon initial public offering, Shares		(477,297)	(7,985,305)	(19,770,070)	28,232,672
Issuance of common stock for cash, net of issuance costs of $15,441	168,559				$ 1	168,558
Issuance of common stock for cash, net of issuance costs of $15,441, Shares					11,499,998
Cashless exercise of common stock warrants					178,847
Stock options exercised	$ 2					2
Stock options exercised, Shares	2,236				2,236
Unrealized loss on marketable securities	$ (28)							$ (28)
Share-based compensation	557					557
Net loss	(92,257)						(92,257)
Closing balance at Sep. 30, 2021	233,360	$ 0	$ 0	$ 0	$ 4	352,606	(119,222)	(28)
Closing balance (Shares) at Sep. 30, 2021		0	0	0	40,470,323
Opening balance at Jun. 30, 2021	(106,079)	$ 1,067	$ 22,963	$ 150,474	$ 0	9,241	(115,320)
Opening balance (Shares) at Jun. 30, 2021		477,297	7,985,305	19,770,070	556,570
Conversion of convertible preferred stock into common stock upon initial public offering	174,504	$ (1,067)	$ (22,963)	$ (150,474)	$ 3	174,501
Conversion of convertible preferred stock into common stock upon initial public offering, Shares		(477,297)	(7,985,305)	(19,770,070)	28,232,672
Issuance of common stock for cash, net of issuance costs of $15,441	168,559				$ 1	168,558
Issuance of common stock for cash, net of issuance costs of $15,441, Shares					11,499,998
Cashless exercise of common stock warrants					178,847
Stock options exercised	2					2
Stock options exercised, Shares					2,236
Unrealized loss on marketable securities	(28)							(28)
Share-based compensation	304					304
Net loss	(3,902)						(3,902)
Closing balance at Sep. 30, 2021	$ 233,360	$ 0	$ 0	$ 0	$ 4	$ 352,606	$ (119,222)	$ (28)
Closing balance (Shares) at Sep. 30, 2021		0	0	0	40,470,323

Condensed Statements of Chang_2

Condensed Statements of Changes in Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021
Common Stock [Member]
Stock issuance Costs	$ 15,441	$ 15,441
Series B Convertible Preferred Stock [Member]
Stock issuance Costs		$ 16

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities
Net loss	$ (92,257)	$ (6,570)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	1
Change in fair value of preferred stock tranche rights liability and preferred stock warrant liability	81,157
Share-based compensation expense	557	116
Amortization of premiums on marketable securities, net	21
Non-cash interest income from marketable securities	(27)
Changes in operating assets and liabilities:
Grant receivable		(187)
Prepaid expenses and other current assets	(4,297)	461
Other assets	(13)	(378)
Accounts payable	(149)	1,231
Accrued expenses and other current liabilities	685	734
Net cash used in operating activities	(14,322)	(4,593)
Cash flows from investing activities
Purchases of available-for-sale marketable securities	(94,095)
Purchases of property and equipment	(14)
Net cash used in investing activities	(94,109)
Cash flows from financing activities
Proceeds from issuance of Series B milestone shares, net of issuance costs	30,031
Proceeds from issuance of common stock upon initial public offering, net of issuance costs	168,559
Proceeds from stock option exercises	2
Net cash provided by financing activities	200,456
Net change in cash and cash equivalents	92,025	(4,593)
Cash and cash equivalents at the beginning of the period	43,777	6,552
Cash and cash equivalents at the end of the period	135,802	$ 1,959
Supplemental disclosure of cash flow information
Cash paid for income taxes
Cash paid for interest
Supplemental disclosure of noncash financing activities
Reclassification of preferred stock tranche rights liability upon share issuance	81,190
Reclassification Of Warrant Liability Upon Exercise Of Preferred Stock Warrant	5,380
Conversion of convertible preferred stock into common stock upon initial public offering	174,504
Common Stock Warrants [Member]
Cash flows from financing activities
Proceeds from exercise of warrants	614
Series A -1 Convertible Preferred Stock Warrant Liability [Member]
Cash flows from financing activities
Proceeds from exercise of warrants	$ 1,250

Description of Organization and

Description of Organization and Business Operations	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Organization and Business Operations	NOTE 1. DESCRIPTION OF ORGANIZATION AND BUSINESS OPERATIONS Acumen Pharmaceuticals, Inc. (“Acumen” or the “Company”) was incorporated in 1996 in the state of Delaware. Acumen discovers and develops targeted therapies for the treatment of Alzheimer’s disease (“AD”). Acumen’s lead drug candidate, ACU193, is a humanized monoclonal antibody which selectively targets amyloid-beta oligomers (“A b “INTERCEPT-AD.” first-in-human INTERCEPT-AD . The Company is subject to the uncertainty of whether the Company’s intellectual property will develop into successful commercial products. November 2020 Reverse Stock Split On November 20, 2020, the Company effected a 1-for-30 reverse June 2021 Reverse Stock Split The Company’s Board of Directors (“Board”) approved a reverse split of shares of the Company’s common stock and convertible preferred stock on a 1-for-1.49 Initial Public Offering On July 6, 2021, the Company issued 9,999,999 shares of common stock in an initial public offering (“IPO”), and on July 8, 2021, the Company issued an additional 1,499,999 shares of common stock that were purchased by the underwriters pursuant to the underwriters’ option to purchase additional shares at the public offering price less underwriting discounts and commissions. The price to the public for each share was $16.00. The aggregate net proceeds from the Company’s IPO, after underwriting discounts and commissions and other offering expenses of $15.4 million, were $168.6 million. On July 6, 2021, in connection with the closing of the IPO, 477,297 shares of Series A, 7,985,305 shares of Series A-1, As a result of the IPO, the underwriters’ exercise of their option, the conversions of the Series A, A-1 Liquidity and Capital Resources The Company has incurred operating losses since inception and expects to continue to incur significant operating losses for the foreseeable future and may never become profitable. As of September 30, 2021 and December 31, 2020, the Company had an accumulated deficit of $119.2 million and $27.0 million, respectively, and working capital of $203.4 million and $38.1 million, respectively. Prior to the IPO, the Company historically relied on raising capital from venture capital firms and private investors and funding from a government grant to finance its operations. On June 9, 2021, the Board and the holders of more than 67% of the then outstanding shares of Series B convertible preferred stock held by the Series B purchasers (the “Requisite Investors”) elected to waive the achievement of the milestone subject to the terms and conditions of the Series B Preferred Stock Purchase Agreement (the “Series B Agreement”) and consummate the subsequent closing (the “Milestone Closing”) (see Note 5). On June 17, 2021, the Milestone Closing for the Series B convertible preferred stock occurred, resulting in the sale of 7,908,027 shares of Series B convertible preferred stock at $3.80 per share for gross proceeds of $30.0 million. As a result of the Milestone Closing and the closing of the Company’s IPO on July 6, 2021, management believes that its existing cash and cash equivalents and marketable securities will be sufficient to enable the Company to fund its operating expenses and capital expenditure requirements at least through 2024. Future capital requirements will depend upon many factors, including the timing and extent of spending on research and development and market acceptance of the Company’s products. The Company may need to obtain additional financing to complete clinical trials and launch and commercialize any product candidates for which it receives regulatory approval. Until such time, if ever, the Company can generate revenue sufficient to achieve profitability, the Company expects to finance its operations through a combination of equity offerings, debt financings, collaborations, strategic alliances and licensing arrangements. There can be no assurance that such financing will be available on terms acceptable to the Company, or at all. To the extent that the Company raises additional capital through the sale of equity or convertible debt securities, the ownership interest of its stockholders will be diluted, and the terms of these securities may include liquidation of other preferences that adversely affect the rights of common stockholders. Debt financing and preferred equity financing, if available, may involve agreements that include covenants limiting or restricting the Company’s ability to take specific actions, such as incurring additional debt, making acquisitions or capital expenditures or declaring dividends. If the Company is unable to maintain sufficient financial resources, its business, financial condition and results of operations will be materially and adversely affected. The Company may be required to delay, limit, reduce or terminate its product discovery and development activities or future commercialization efforts. In October 2021, the Company announced the initial dosing of the first patient in the INTERCEPT-AD trial and subsequently successfully cleared its sentinel safety review. Clinical trial site activation and patient recruitment and enrollment is ongoing. The Company has experienced delays in clinical site activation and patient enrollment in INTERCEPT-AD, (“COVID-19”) INTERCEPT-AD. COVID-19, COVID-19 INTERCEPT-AD. COVID-19 COVID-19

Basis of Presentation, Summary

Basis of Presentation, Summary of Significant Accounting Policies and Recent Accounting Pronouncements	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation, Summary of Significant Accounting Policies and Recent Accounting Pronouncements	NOTE 2. BASIS OF PRESENTATION, SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND RECENT ACCOUNTING PRONOUNCEMENTS Basis of Presentation The accompanying condensed financial statements have been prepared in accordance with Generally Accepted Accounting Principles in the United States of America (“U.S. GAAP”) for interim financial information and the instructions to Form 10-Q S-X. Emerging Growth Company From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”), or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the impact of recently issued standards that are not yet effective will not have a material impact on the Company’s condensed financial statements upon adoption. Under the Jumpstart Our Business Startups Act of 2012, as amended, the Company meets the definition of an emerging growth company and has elected the extended transition period for complying with new or revised accounting standards, which delays the adoption of these accounting standards until they would apply to private companies. Use of Estimates The preparation of condensed financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the condensed financial statements and the reported amounts of expenses during the reporting period. These estimates and assumptions are based on current facts and historical experience, as well as other pertinent industry and regulatory authority information, including the potential future effects of the COVID-19 Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of three months or less at the date of purchase to be cash equivalents. The Company’s cash equivalents consist of funds held in several money market accounts. The Company had $134.8 million and $36.8 million in cash equivalents as of September 30, 2021 and December 31, 2020, respectively. Marketable Securities The Company considers its debt securities to be available-for-sale Available-for-sale available-for-sale Securities that are classified as available-for-sale available-for-sale available-for-sale Marketable securities are subject to a periodic impairment review. The Company may recognize an impairment charge when a decline in the fair value of investments below the cost basis is determined to be other-than-temporary. In determining whether a decline in market value is other-than-temporary, various factors are considered, including the cause, duration of time and severity of the impairment, any adverse changes in the investees’ financial condition and the Company’s intent and ability to hold the security for a period of time sufficient to allow for an anticipated recovery in market value. Declines in value judged to be other-than-temporary are included in the Company’s condensed statements of operations and comprehensive loss. The Company did not record any other-than-temporary impairments related to marketable securities in the Company’s condensed statements of operations and comprehensive loss for the three and nine months ended September 30, 2021 and 2020. Concentrations of Credit Risk Financial instruments that potentially subject the Company to significant concentration of credit risk consist primarily of cash and cash equivalents and marketable securities. Periodically, the Company may maintain deposits in financial institutions in excess of government insured limits. Management believes that the Company is not exposed to significant credit risk as the Company’s deposits are held at financial institutions that management believes to be of high credit quality. The Company has not experienced any losses on these deposits. The Company’s marketable securities portfolio consists primarily of investments in money market funds, commercial paper and short-term high credit quality corporate debt securities. Fair Value of Financial Instruments The Company’s financial assets and liabilities are accounted for in accordance with Accounting Standards Codification (“ASC”) 820, Fair Value Measurements and Disclosure , Level 1— Observable inputs, such as quoted prices in active markets for identical assets or liabilities. Level 2—Inputs other than Level 1 inputs that are either directly or indirectly observable, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the instrument’s anticipated life. Level 3—Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions. To the extent the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair values requires more judgement. Accordingly, the degree of judgement exercised by management in determining fair value is greatest for instruments categorized as Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The carrying values reported in the Company’s condensed balance sheets for cash (excluding cash equivalents which are recorded at fair value on a recurring basis), grant receivable, accounts payable, and accrued expenses are reasonable estimates of their fair values due to the short-term nature of these items. The following tables present the Company’s fair value hierarchy for its money market securities, available-for-sale Fair value measurements at reporting date using Quoted Prices in Significant Other Significant (Level 3) Fair Value at Assets included in: Cash and cash equivalents Money market securities $ 134,800 $ — $ — $ 134,800 Marketable securities Commercial paper — 43,923 — 43,923 Corporate debt securities — 24,888 — 24,888 Asset-backed securities — 19,273 — 19,273 U.S. treasury securities — 5,988 — 5,988 Total fair value $ 134,800 $ 94,072 $ — $ 228,872 Fair value measurements at reporting date using Quoted Prices in Significant Other Significant Fair Value at Assets included in: Cash and cash equivalents Money market securities $ 36,758 $ — $ — $ 36,758 Total fair value $ 36,758 $ — $ — $ 36,758 Liabilities included in: Preferred stock tranche rights liability $ — $ — $ 5,033 $ 5,033 Preferred stock warrant liability — — 380 380 Total fair value $ — $ — $ 5,413 $ 5,413 The fair value of the Company’s money market funds is determined using quoted market prices in active markets for identical assets. The Company’s portfolio of marketable securities is comprised of commercial paper, asset-backed securities, U.S. treasury securities and short-term highly liquid, high credit quality corporate debt securities. The fair value for the available-for-sale Refer to Note 5 for further information about the Level 3 rollforward of activity and Level 3 inputs. Grant Receivable Grant receivable consists of research expenses reimbursable under a grant from the National Institute of Health (“NIH”). The Company carries its grant receivable at the unreimbursed amount. On a periodic basis, the Company evaluates its grant receivable to determine whether an allowance is required. The allowance is management’s best estimate of probable losses. Management determined that no allowance was necessary as of September 30, 2021 and December 31, 2020. Property and Equipment Property and equipment consists primarily of computer equipment and is stated at cost and depreciated using the straight-line method over the estimated useful lives of the assets, which is generally three years for computer-related assets. Convertible Preferred Stock The Company recorded shares of convertible preferred stock at their respective fair values on the dates of issuance, net of issuance costs. The Company applied the guidance in ASC 480-10-S99-3A, SEC Staff Announcement: Classification and Measurement of Redeemable Securities A-1 As mentioned above in Note 1, in connection with the closing of the IPO, all of the outstanding shares of Series A, Series A-1 Preferred Stock Tranche Rights Liability The Company determined that its obligation to issue, and the Company’s investors’ right to purchase, additional shares of Series B convertible preferred stock pursuant to the Milestone Closing (see Note 1 and Note 5) represented a freestanding financial instrument (the “tranche liability”). The tranche liability was initially recorded at fair value. The proceeds from the sale of the convertible preferred stock were first allocated to the fair value of the tranche liability with the remaining proceeds from the sale of the convertible preferred stock allo c Preferred Stock Warrant Liability The Company accounted for the warrant to purchase Series A-1 Common Stock Warrants The Company assesses whether warrants issued require accounting as derivatives. The Company determined that its common stock warrants were (1) indexed to the Company’s own stock and (2) classified in stockholders’ equity in accordance with FASB ASC Topic 815, Derivatives and Hedging Grant and Other Revenue Recognition The Company’s NIH grant is not within the scope of ASC 606, Revenue from Contracts with Customers , non-reciprocal 958-605, Not-for-Profit-Entities-Revenue In the absence of applicable guidance under U.S. GAAP, the Company’s policy is to recognize grant revenue when the related costs are incurred and the right to payment is realized. Costs incurred are recorded in research and development and general and administrative expenses on the accompanying condensed statements of operations and comprehensive loss. The Company believes the recognition of revenue as costs are incurred and amounts become realizable is analogous to the concept of transfer of control of a service over time under ASC 606. Research and Development Expenses Research and development expenses primarily consist of consultants and materials, biologic storage, salaries and other personnel-related expenses related to research and development activities and are expensed as incurred. Payments for these activities are based on the terms of the individual agreements, which may differ from the pattern of costs incurred, and are reflected on the condensed balance sheets as prepaid or accrued expenses. The Company records accruals for estimated ongoing research costs. When evaluating the adequacy of the accrued liabilities, the Company analyzes progress of the studies, including the phase or completion of events, invoices received and contracted costs. Share-based Compensation The Company expenses share-based compensation to employees, non-employees non-employee’s . Income Taxes Income taxes are recorded in accordance with ASC 740, Income Taxes The Company accounts for uncertain tax positions in accordance with the provisions of ASC 740. 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 has not recorded any accruals related to uncertain tax positions as of September 30, 2021 and December 31, 2020. The Company’s policy is to record interest and penalties, if any, as part of income tax benefit. No interest or penalties were recorded during the nine months ended September 30, 2021 and 2020. Net Loss Per Share of Common Stock Basic net loss per share of common stock is calculated using the two-class if-converted Segment Information Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one segment. Recently Issued Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes 2019-12”), 2019-12

Marketable Securities

Marketable Securities	9 Months Ended
	Sep. 30, 2021
Marketable Securities [Abstract]
Marketable Securities	NOTE 3. MARKETABLE SECURITIES Marketable securities consisted of the following as of September 30, 2021 (in thousands): Amortized Gross Unrealized Gross Unrealized Fair Available-for-sale Commercial paper $ 43,923 $ — $ — $ 43,923 Corporate debt securities 8,043 — (2 ) 8,041 Asset-backed securities 12,200 — (2 ) 12,198 Total available-for-sale 64,166 — (4 ) 64,162 Available-for-sale Corporate debt securities 16,866 — (20 ) 16,846 Asset-backed securities 7,080 — (4 ) 7,076 U.S. treasury securities 5,988 — — 5,988 Total available-for-sale 29,934 — (24 ) 29,910 Total available-for-sale $ 94,100 $ — $ (28 ) $ 94,072 As of September 30, 2021, the Company’s available-for-sale available-for-sale available-for-sale available-for-sale

Supplemental Financial Informat

Supplemental Financial Information	9 Months Ended
	Sep. 30, 2021
Supplemental Financial Information [Abstract]
Supplemental Financial Information	NOTE 4. SUPPLEMENTAL FINANCIAL INFORMATION Prepaid expenses and other current assets consisted of the following (in thousands): September 30, December 31, Prepaid insurance $ 2,299 $ 5 Research and development service agreements 2,077 432 Prepaid raw materials 248 91 Other 216 15 Total prepaid expenses and other current assets $ 4,840 $ 543 Accrued expenses and other current liabilities consisted of the following (in thousands): September 30, December 31, Bonuses and other employee liabilities $ 797 $ — Research and development 191 133 Other 119 90 Professional fees — 200 Total accrued expenses and other current liabilities $ 1,107 $ 423

Convertible Preferred Stock, Tr

Convertible Preferred Stock, Tranche Liability and Warrant Liability	9 Months Ended
	Sep. 30, 2021
Convertible Preferred Stock Tranche Liability and Warrant Liability [Abstract]
Convertible Preferred Stock, Tranche Liability and Warrant Liability	NOTE 5. CONVERTIBLE PREFERRED STOCK, TRANCHE LIABILITY AND WARRANT LIABILITY Convertible Preferred Stock On November 20, 2020, the Company entered into the Series B Agreement for a private placement of up to 19,770,070 shares of Series B convertible preferred stock, $0.0001 par value per share, at an original issuance price of $3.80 per share, subject to separate closings, including: (1) 11,862,043 shares at the Initial Closing on November 20, 2020, and (2) 7,908,027 shares at a subsequent closing that would be triggered by the achievement of a specific clinical milestone. The Series B Agreement obligated the Company to issue and sell and the Series B purchasers to purchase up to a total of 7,908,027 additional shares of Series B convertible preferred stock (the “Milestone Shares”) at the same price per share upon the achievement of a certain defined clinical milestone. The determination as to whether the milestone event has been met was subject to certification by the Board and the Requisite Investors. Each Series B convertible preferred stock investor had the right, but not the obligation, to purchase all or any portion of the Milestone Shares at any time in its sole option and in its sole and absolute discretion, whether or not the Company achieved the applicable clinical milestone. See “ Series B Convertible Preferred Stock Tranche Rights Liability As discussed above in Note 1, on June 9, 2021, the Board and the Requisite Investors elected to waive the achievement of the milestone subject to the terms and conditions of the Series B Agreement and consummate the Milestone Closing and, on June 17, 2021, the Milestone Closing occurred, resulting in the sale of 7,908,027 shares of Series B convertible preferred stock at $3.80 per share for gross proceeds of $30.0 million, bringing the total number of Series B convertible preferred shares outstanding to 19,770,070. On June 22, 2021, a warrant to purchase 447,426 shares of Series A-1 “Series A-1 A-1 Additionally, on July 6, 2021, in connection with the closing of the IPO, 477,297 shares of Series A, 7,985,305 shares of Series A-1, Convertible preferred stock consisted of the following as of Dec e Shares Shares Weighted Average Carrying Liquidation Series A 711,203 477,297 $ 2.24 $ 1,067 $ 1,067 Series A-1 11,898,177 7,537,879 2.24 16,333 16,847 Series B 29,457,450 11,862,043 3.80 39,253 45,070 Total 42,066,830 19,877,219 $ 56,653 $ 62,984 Dividends The holders of Series B, Series A-1 Liquidation preference In the event of any voluntary or involuntary liquidation, dissolution or winding up of the Company, holders of Series B convertible preferred stock were entitled to receive, prior and in preference to, holders of Series A-1 In the event of any voluntary or involuntary liquidation, dissolution or winding up of the Company, holders of Series A-1 A-1 A-1 In the event of any voluntary or involuntary liquidation, dissolution or winding up of the Company, holders of Series A convertible preferred stock were entitled to receive, prior and in preference to, holders of common stock, in the amount of the original issue price plus any declared but unpaid dividends thereon. If upon occurrence of such an event, the assets and funds to be distributed among the holders of Series A convertible preferred stock were insufficient to permit full payment to such holders, the entire assets and funds of the Company legally available for distribution would have been distributed ratably among the holders of the Series A convertible preferred stock. Conversion rights Shares of all series of convertible preferred stock were convertible into such number of fully paid and non-assessable Each share of convertible preferred stock was convertible at any time at the option of the holder at the conversion ratio then in effect. In addition, each share of convertible preferred stock was to be automatically converted into common stock at the conversion ratio then in effect upon either (a) the closing of an underwritten public offering resulting in gross proceeds to the Company of at least $75 million and at a price per share equal to at least two times the Series B original issuance price, or $7.60 (subject to adjustment in the event of any stock dividend, stock split, combination or other similar recapitalization with respect to the Series B convertible preferred stock), or (b) the date and time, or the occurrence of an event, specified in such vote or written consent of at least 67% of the holders of the then outstanding shares of Series B convertible preferred stock. If any Series B purchaser failed to purchase its respective portion of the Milestone Shares upon occurrence of the Milestone Closing, each existing share of Series B convertible preferred stock held by such stockholder would have automatically converted into one share of common stock two days after the Milestone Closing. On July 6, 2021, in connection with the closing of the IPO, each outstanding share of Series A, Series A-1 Voting rights Holders of convertible preferred stock were entitled to vote as a single class together with the holders of common stock and had one vote for each share of common stock into which the convertible preferred stock was convertible. The holders of Series B convertible preferred stock were entitled to elect two directors to the Board, and the holders of Series A and Series A-1 A majority of the outstanding shares of convertible preferred stock was necessary for approving certain matters, including the ability to either increase or decrease the authorized number of directors constituting the Board, pursuant to protective provisions in the Company’s amended and restated certificate of incorporation. Series B Convertible Preferred Stock Tranche Rights Liability The Company concluded that the tranche liability met the definition of a freestanding financial instrument, as it was legally detachable and separately exercisable from the initial closing of the Series B convertible preferred stock. The fair value for the tranche liability was estimated as a forward contract using a valuation model, calibrated at issuance. The valuation model at issuance estimated the implied value of the Series B stock as of the expected milestone date utilizing the probability of milestone achievement, expected timing of milestone achievement, and risk-free rate. The model was calibrated such that the value of the initial tranche and the forward contract were equal to the initial tranche proceeds at issuance. Subsequently, the fair value of the liability was discounted to the valuation date and adjusted for probability of the achievement of the milestone event. The calibrated valuation model was updated as of December 31, 2020, March 31, 2021 and in the Stay Private scenario utilized in the hybrid methodology as of June 17, 2021 (the date of the Milestone Closing). Significant estimates and assumptions impacting fair value include the discount rate, expected time to the Milestone Closing, and probability of the Milestone Closing. The discount rate was equal to the risk-free rate commensurate with the estimated timing of the Milestone Closing. The following assumptions were used in the estimation of the fair value of the tranche liability as a forward contract as of each of the dates indicated: June 17, December 31, 2021 2020 Risk-free interest rate 0.07 % 0.12 % Expected time to Milestone Closing (in years) 0.8 1.3 Probability of achievement of Milestone Closing 100 % 65 % For the other portion of the hybrid method used as of June 17, 2021, the fair value for the tranche liability was estimated based upon an allocation of the underlying equity value, which was determined using an IPO value as estimated through analysis of IPOs for comparable guideline companies, to arrive at a value per share in the IPO scenario. The estimated fair value of the tranche liability was $81,190,000 and $5,033,000 as of the Milestone Closing on June 17, 2021 and December 31, 2020, respectively. The significant increase in the June 17, 2021 valuation stems from both a shift in methodology from an option pricing method (“OPM”) to a Hybrid Model where the concluded value of the forward tranche is derived by the sum of the probability weighted present value of the forward tranche in the Stay Private and IPO scenarios (with the former including all other potential exit scenarios other than an imminent IPO), as well as the increase in the probability of achievement of the Milestone Closing. The resulting difference in estimated fair value was recognized as a change in fair value within other income in the accompanying condensed statements of operations. The tranche liability was revalued each reporting period with the change in fair value recorded in the accompanying condensed statements of operations and comprehensive loss through the issuance of the Milestone Shares on June 17, 2021. Following the Milestone Closing, the remaining tranche liability was reclassified to convertible preferred stock on the condensed balance sheet. Series A-1 On October 19, 2018, the Company issued a 10-year A-1 A-1 The warrant liability met the definition of a freestanding financial instrument, as it was legally detachable and separately exercisable from the initial closing of the Series A-1 The fair value of the warrant liability was estimated using the OPM backsolve method as of December 31, 2020 and using a hybrid method, which included an OPM backsolve in the Stay Private scenario as of June 22, 2021. The following assumptions were used in the estimation of the fair value of the warrant liability using the OPM backsolve method as of each of the dates indicated: June 22, December 31, Risk-free interest rate 0.25 % 0.13 % Expected term (in years) 2.0 2.0 Expected volatility 90 % 90 % Expected dividend yield 0 % 0 % The hybrid method used to value the warrant liability at June 22, 2021 considered both the underlying equity value determined using the OPM backsolve method in a Stay Private scenario, as well as the underlying equity value that was determined using an expected IPO value as estimated through analysis of IPOs for comparable guideline companies, to arrive at a value per share in the IPO scenario. The underlying equity values from each approach were probability weighted based upon the expected likelihood of each scenario. The fair value of the warrant liability was estimated to be $12.02 and $0.85 as of June 22, 2021 and December 31, 2020, respectively. The following table provides a reconciliation of the tranche liability and warrant liability measured at fair value using Level 3 significant unobservable inputs (in thousands): Series A-1 Series B Total Balance, December 31, 2020 $ 380 $ 5,033 $ 5,413 Change in fair value 5,000 76,157 81,157 Settlement of tranche liability due to issuance of Milestone Shares — (81,190 ) (81,190 ) Settlement of warrant liability upon exercise of warrant (5,380 ) — (5,380 ) Balance, September 30, 2021 $ — $ — $ —

Stockholders' Equity (Deficit)

Stockholders' Equity (Deficit)	9 Months Ended
	Sep. 30, 2021
Stockholders' Equity Note [Abstract]
Stockholders' Equity (Deficit)	NOTE 6. STOCKHOLDERS’ EQUITY (DEFICIT) Authorized Shares On July 6, 2021, the Company issued 9,999,999 shares of common stock in an IPO, Effective upon the closing of the IPO on July 6, 2021, the Company amended its certificate of incorporation such that the total number of shares of all classes of capital stock authorized to be issued was increased to 310,000,000, with 10,000,000 shares designated as preferred stock with a par value of $0.0001, and 300,000,000 shares designated as common stock with a par value of $0.0001. The Company amended its certificate of incorporation on November 20, 2020, such that the total number of shares of common stock authorized to be issued was increased to 50,500,000, and the total number of shares of preferred stock authorized to be issued was increased to 42,066,830, of which 711,203 were designated Series A convertible preferred stock, 11,898,177 were designated as Series A-1 convertible Common Stock As of September 30, 2021, the Company’s Amended and Restated Certificate of Incorporation authorized the issuance of 300,000,000 shares of common stock, $0.0001 par value per share. Each share of common stock is entitled to one voting right. Common Stock Warrants In accordance with ASC 815, the common stock warrants issued in 2014 through 2017 did not meet the definition of a derivative and were classified in stockholders’ deficit in the condensed consolidated balance sheets. In June 2021, several holders of warrants to purchase the Company’s common stock exercised their warrants and purchased a total of 137,446 shares of common stock at an exercise price of $4.47, leaving 248,247 common stock warrants outstanding as of June 30, 2021. On July 6, 2021, the Company issued 178,847 shares of common stock in exchange for the remaining 248,247 outstanding common stock warrants at an exercise price of $4.47. As of September 30, 2021, there were no common stock warrants outstanding. As of December 31, 2020, the outstanding warrants to purchase the Company’s common stock were comprised of the following: Equity Upon Exercise Expiration Dates Number of Warrants issued in 2014 Common Stock $ 4.47 3/21/2024 - 6/30/2025 83,726 Warrants issued in 2015 Common Stock $ 4.47 6/30/2025 209,690 Warrants issued in 2016 Common Stock $ 4.47 6/30/2025 34,396 Warrants issued in 2017 Common Stock $ 4.47 6/30/2025 57,881 Total Warrants 385,693

Share-Based Compensation

Share-Based Compensation	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
Share-Based Compensation	N 2021 Equity Incentive Plan The 2021 Equity Incentive Plan (the “2021 Plan”), which provides for the grant of incentive stock options to employees, and the grant of nonstatutory stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, performance awards and other forms of stock awards to employees, directors and consultants, became effective on June 30, 2021. Initially, the maximum number of shares of the Company’s common stock that may be issued under the 2021 Plan was 7,698,282 shares, which is the sum of (1) 3,550,000 new shares, plus (2) 667,104 shares remained available for issuance under the 2021 Plan. The 2013 Plan provided for the grant of incentive stock options, nonstatutory stock options, issuance of shares of restricted stock and other equity awards to the Company’s employees, officers, directors, consultants and advisors. All outstanding awards issued under the 2013 Plan remain subject to the terms of the 2013 Plan. As of September 30, 2021, there were 3,478,942 options outstanding under the 2013 Plan. Stock Options The Black-Scholes option-pricing model was used to estimate the fair value of stock options granted during the nine months ended September 30, 2021 with the following weighted average assumptions: Risk-free interest rate 0.4% - 1.1 % Expected term in years 5.3 - 6.1 Expected volatility 90 % Expected dividend yield 0 % The weighted average grant date fair value of options granted during the nine months ended September 30, 2021, was $1.34 per share. There were no options granted during the three months ended September 30, 2021, nor did the Company grant any options during the three or nine months ended September 30, 2020. The fair value of the Company’s common stock underlying the stock options has historically been determined by the Board with assistance from management and, occasionally with input from an independent third-party valuation firm. For the year ended December 31, 2020, management engaged an independent third-party valuation firm to provide an estimate of the fair value of its common stock. The fair value of common stock was determined considering a number of objective and subjective factors, including valuations of comparable companies, sales of convertible preferred stock, operating and financial performance, the lack of liquidity of the Company’s common stock and the general and industry-specific economic outlook. As of June 30, 2021, the date of the last option grant, and December 31, 2020 , Risk-free interest rate 0.13 % Expected time to liquidity event in years 2.0 Expected volatility 90 % Expected dividend yield 0 % The stock options granted after December 31, 2017 vest monthly over 24 or 36 months and have a ten-year three ten-year The following table reflects summarized stock option activity: Stock Options Weighted Average Weighted Average Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2020 1,001,517 $ 1.13 Granted 2,663,084 2.21 Exercised (2,236 ) 0.72 Outstanding at September 30, 2021 3,662,365 $ 1.92 8.7 $ 51,591 Vested and exercisable at September 30, 2021 958,709 $ 1.38 7.1 $ 14,034 As of September 30, 2021, total unrecognized compensation costs related to unvested stock option awards granted was approximately $3.1 million, which the Company expects to recognize over a weighted-average period of approximately 3.2 years. T Three Months Ended Nine Months Ended 2021 2020 2021 2020 General and administrative $ 254 $ 26 $ 412 $ 78 Research and development 50 13 145 38 Total share-based compensation $ 304 $ 39 $ 557 $ 116 Employee Stock Purchase Plan The 2021 Employee Stock Purchase Plan (the “ESPP”), which permits employees to purchase shares of the Company’s common stock, became effective on June 30, 2021. A total of 375,000 shares of the Company’s common stock were initially reserved for sale under the ESPP. The number of shares of the Company’s common stock reserved for issuance will automatically increase on January 1 of each calendar year, beginning on January 1, 2022 through January 1, 2031, by the lesser of (1) 1% of the total number of shares of the Company’s common stock outstanding on the last day of the fiscal year before the date of the automatic increase, and (2) 800,000 shares; provided that before the date of any such increase, the Board may determine that such increase will be less than the amount set forth in clauses (1) and (2). As of September 30, 2021, there have been no purchases of shares under the ESPP.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	NOTE 8. COMMITMENTS AND CONTINGENCIES The Company is not a party to any material legal proceedings and is not aware of any pending or threatened claims. From time to time, the Company may be subject to various legal proceedings and claims that arise in the ordinary course of its business activities. Leases The Company has been subleasing space in Indiana since March 1, 2020, under a lease that initially expired on December 31, 2020. The Company executed a new sublease for this space that was effective February 1, 2021. The term of the sublease is for 31 months, expiring on August 30, 2023. The Company pays monthly rent of $12,719 and is allowing others to sublease a portion of the space from the Company for less than a one-year As of September 30, 2021, future minimum lease payments under this lease agreement associated with the Company’s operations were as follows (in thousands): Year ended December 31, 2021 (remaining 3 months) $ 38 Year ended December 31, 2022 153 Year ended December 31, 2023 102 Total $ 293

Net Loss Per Share

Net Loss Per Share	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Net Loss Per Share	NOTE 9. NET LOSS PER SHARE The Company computes loss per common share using the two-class The table below provides potentially dilutive securities not included in the calculation of the diluted net loss per common share because to do so would be anti-dilutive: Nine Months Ended 2021 2020 Shares issuable upon conversion of Series A Preferred Stock — 477,297 Shares issuable upon conversion of Series A-1 — 7,537,879 Shares issuable upon exercise of stock options 3,662,365 1,004,898 Shares issuable upon exercise of common stock warrants — 385,693 Shares issuable upon exercise of preferred stock warrant — 447,426 Total 3,662,365 9,853,193

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2021
Subsequent Events [Abstract]
Subsequent Events	NOTE 10. SUBSEQUENT EVENTS The Company has completed an evaluation of all subsequent events through November 15, 2021 to ensure that these financial statements include appropriate disclosure of events both recognized in the financial statements and events which occurred but were not recognized in the financial statements.

Basis of Presentation, Summary

Basis of Presentation, Summary of Significant Accounting Policies and Recent Accounting Pronouncements (Policies)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed financial statements have been prepared in accordance with Generally Accepted Accounting Principles in the United States of America (“U.S. GAAP”) for interim financial information and the instructions to Form 10-Q S-X.
Emerging Growth Company	Emerging Growth Company From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”), or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the impact of recently issued standards that are not yet effective will not have a material impact on the Company’s condensed financial statements upon adoption. Under the Jumpstart Our Business Startups Act of 2012, as amended, the Company meets the definition of an emerging growth company and has elected the extended transition period for complying with new or revised accounting standards, which delays the adoption of these accounting standards until they would apply to private companies.
Use of Estimates	Use of Estimates The preparation of condensed financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the condensed financial statements and the reported amounts of expenses during the reporting period. These estimates and assumptions are based on current facts and historical experience, as well as other pertinent industry and regulatory authority information, including the potential future effects of the COVID-19
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of three months or less at the date of purchase to be cash equivalents. The Company’s cash equivalents consist of funds held in several money market accounts. The Company had $134.8 million and $36.8 million in cash equivalents as of September 30, 2021 and December 31, 2020, respectively.
Marketable Securities	Marketable Securities The Company considers its debt securities to be available-for-sale Available-for-sale available-for-sale Securities that are classified as available-for-sale available-for-sale available-for-sale Marketable securities are subject to a periodic impairment review. The Company may recognize an impairment charge when a decline in the fair value of investments below the cost basis is determined to be other-than-temporary. In determining whether a decline in market value is other-than-temporary, various factors are considered, including the cause, duration of time and severity of the impairment, any adverse changes in the investees’ financial condition and the Company’s intent and ability to hold the security for a period of time sufficient to allow for an anticipated recovery in market value. Declines in value judged to be other-than-temporary are included in the Company’s condensed statements of operations and comprehensive loss. The Company did not record any other-than-temporary impairments related to marketable securities in the Company’s condensed statements of operations and comprehensive loss for the three and nine months ended September 30, 2021 and 2020.
Concentrations of Credit Risk	Concentrations of Credit Risk Financial instruments that potentially subject the Company to significant concentration of credit risk consist primarily of cash and cash equivalents and marketable securities. Periodically, the Company may maintain deposits in financial institutions in excess of government insured limits. Management believes that the Company is not exposed to significant credit risk as the Company’s deposits are held at financial institutions that management believes to be of high credit quality. The Company has not experienced any losses on these deposits. The Company’s marketable securities portfolio consists primarily of investments in money market funds, commercial paper and short-term high credit quality corporate debt securities.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company’s financial assets and liabilities are accounted for in accordance with Accounting Standards Codification (“ASC”) 820, Fair Value Measurements and Disclosure , Level 1— Observable inputs, such as quoted prices in active markets for identical assets or liabilities. Level 2—Inputs other than Level 1 inputs that are either directly or indirectly observable, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the instrument’s anticipated life. Level 3—Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions. To the extent the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair values requires more judgement. Accordingly, the degree of judgement exercised by management in determining fair value is greatest for instruments categorized as Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The carrying values reported in the Company’s condensed balance sheets for cash (excluding cash equivalents which are recorded at fair value on a recurring basis), grant receivable, accounts payable, and accrued expenses are reasonable estimates of their fair values due to the short-term nature of these items. The following tables present the Company’s fair value hierarchy for its money market securities, available-for-sale Fair value measurements at reporting date using Quoted Prices in Significant Other Significant (Level 3) Fair Value at Assets included in: Cash and cash equivalents Money market securities $ 134,800 $ — $ — $ 134,800 Marketable securities Commercial paper — 43,923 — 43,923 Corporate debt securities — 24,888 — 24,888 Asset-backed securities — 19,273 — 19,273 U.S. treasury securities — 5,988 — 5,988 Total fair value $ 134,800 $ 94,072 $ — $ 228,872 Fair value measurements at reporting date using Quoted Prices in Significant Other Significant Fair Value at Assets included in: Cash and cash equivalents Money market securities $ 36,758 $ — $ — $ 36,758 Total fair value $ 36,758 $ — $ — $ 36,758 Liabilities included in: Preferred stock tranche rights liability $ — $ — $ 5,033 $ 5,033 Preferred stock warrant liability — — 380 380 Total fair value $ — $ — $ 5,413 $ 5,413 The fair value of the Company’s money market funds is determined using quoted market prices in active markets for identical assets. The Company’s portfolio of marketable securities is comprised of commercial paper, asset-backed securities, U.S. treasury securities and short-term highly liquid, high credit quality corporate debt securities. The fair value for the available-for-sale Refer to Note 5 for further information about the Level 3 rollforward of activity and Level 3 inputs.
Grant Receivable	Grant Receivable Grant receivable consists of research expenses reimbursable under a grant from the National Institute of Health (“NIH”). The Company carries its grant receivable at the unreimbursed amount. On a periodic basis, the Company evaluates its grant receivable to determine whether an allowance is required. The allowance is management’s best estimate of probable losses. Management determined that no allowance was necessary as of September 30, 2021 and December 31, 2020.
Property and Equipment	Property and Equipment Property and equipment consists primarily of computer equipment and is stated at cost and depreciated using the straight-line method over the estimated useful lives of the assets, which is generally three years for computer-related assets.
Convertible Preferred Stock	Convertible Preferred Stock The Company recorded shares of convertible preferred stock at their respective fair values on the dates of issuance, net of issuance costs. The Company applied the guidance in ASC 480-10-S99-3A, SEC Staff Announcement: Classification and Measurement of Redeemable Securities A-1 As mentioned above in Note 1, in connection with the closing of the IPO, all of the outstanding shares of Series A, Series A-1
Preferred Stock Tranche Rights Liability	Preferred Stock Tranche Rights Liability The Company determined that its obligation to issue, and the Company’s investors’ right to purchase, additional shares of Series B convertible preferred stock pursuant to the Milestone Closing (see Note 1 and Note 5) represented a freestanding financial instrument (the “tranche liability”). The tranche liability was initially recorded at fair value. The proceeds from the sale of the convertible preferred stock were first allocated to the fair value of the tranche liability with the remaining proceeds from the sale of the convertible preferred stock allo c
Preferred Stock Warrant Liability	Preferred Stock Warrant Liability The Company accounted for the warrant to purchase Series A-1
Common Stock Warrants	Common Stock Warrants The Company assesses whether warrants issued require accounting as derivatives. The Company determined that its common stock warrants were (1) indexed to the Company’s own stock and (2) classified in stockholders’ equity in accordance with FASB ASC Topic 815, Derivatives and Hedging
Grant and Other Revenue Recognition	Grant and Other Revenue Recognition The Company’s NIH grant is not within the scope of ASC 606, Revenue from Contracts with Customers , non-reciprocal 958-605, Not-for-Profit-Entities-Revenue In the absence of applicable guidance under U.S. GAAP, the Company’s policy is to recognize grant revenue when the related costs are incurred and the right to payment is realized. Costs incurred are recorded in research and development and general and administrative expenses on the accompanying condensed statements of operations and comprehensive loss. The Company believes the recognition of revenue as costs are incurred and amounts become realizable is analogous to the concept of transfer of control of a service over time under ASC 606.
Research and Development Expense	Research and Development Expenses Research and development expenses primarily consist of consultants and materials, biologic storage, salaries and other personnel-related expenses related to research and development activities and are expensed as incurred. Payments for these activities are based on the terms of the individual agreements, which may differ from the pattern of costs incurred, and are reflected on the condensed balance sheets as prepaid or accrued expenses. The Company records accruals for estimated ongoing research costs. When evaluating the adequacy of the accrued liabilities, the Company analyzes progress of the studies, including the phase or completion of events, invoices received and contracted costs.
Share-based Compensation	Share-based Compensation The Company expenses share-based compensation to employees, non-employees non-employee’s .
Income Taxes	Income Taxes Income taxes are recorded in accordance with ASC 740, Income Taxes The Company accounts for uncertain tax positions in accordance with the provisions of ASC 740. 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 has not recorded any accruals related to uncertain tax positions as of September 30, 2021 and December 31, 2020. The Company’s policy is to record interest and penalties, if any, as part of income tax benefit. No interest or penalties were recorded during the nine months ended September 30, 2021 and 2020.
Net Loss Per Share of Common Stock	Net Loss Per Share of Common Stock Basic net loss per share of common stock is calculated using the two-class if-converted
Segment Information	Segment Information Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one segment.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes 2019-12”), 2019-12

Basis of Presentation, Summa_2

Basis of Presentation, Summary of Significant Accounting Policies and Recent Accounting Pronouncements (Tables)	9 Months Ended
	Sep. 30, 2021
Accounting Policies [Abstract]
Summary of Fair Value Measurements, Recurring and Nonrecurring	The following tables present the Company’s fair value hierarchy for its money market securities, available-for-sale Fair value measurements at reporting date using Quoted Prices in Significant Other Significant (Level 3) Fair Value at Assets included in: Cash and cash equivalents Money market securities $ 134,800 $ — $ — $ 134,800 Marketable securities Commercial paper — 43,923 — 43,923 Corporate debt securities — 24,888 — 24,888 Asset-backed securities — 19,273 — 19,273 U.S. treasury securities — 5,988 — 5,988 Total fair value $ 134,800 $ 94,072 $ — $ 228,872 Fair value measurements at reporting date using Quoted Prices in Significant Other Significant Fair Value at Assets included in: Cash and cash equivalents Money market securities $ 36,758 $ — $ — $ 36,758 Total fair value $ 36,758 $ — $ — $ 36,758 Liabilities included in: Preferred stock tranche rights liability $ — $ — $ 5,033 $ 5,033 Preferred stock warrant liability — — 380 380 Total fair value $ — $ — $ 5,413 $ 5,413

Marketable Securities (Tables)

Marketable Securities (Tables)	9 Months Ended
	Sep. 30, 2021
Marketable Securities [Abstract]
Summary of Marketable securities	Marketable securities consisted of the following as of September 30, 2021 (in thousands): Amortized Gross Unrealized Gross Unrealized Fair Available-for-sale Commercial paper $ 43,923 $ — $ — $ 43,923 Corporate debt securities 8,043 — (2 ) 8,041 Asset-backed securities 12,200 — (2 ) 12,198 Total available-for-sale 64,166 — (4 ) 64,162 Available-for-sale Corporate debt securities 16,866 — (20 ) 16,846 Asset-backed securities 7,080 — (4 ) 7,076 U.S. treasury securities 5,988 — — 5,988 Total available-for-sale 29,934 — (24 ) 29,910 Total available-for-sale $ 94,100 $ — $ (28 ) $ 94,072

Supplemental Financial Inform_2

Supplemental Financial Information (Tables)	9 Months Ended
	Sep. 30, 2021
Supplemental Financial Information [Abstract]
Schedule of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consisted of the following (in thousands): September 30, December 31, Prepaid insurance $ 2,299 $ 5 Research and development service agreements 2,077 432 Prepaid raw materials 248 91 Other 216 15 Total prepaid expenses and other current assets $ 4,840 $ 543
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consisted of the following (in thousands): September 30, December 31, Bonuses and other employee liabilities $ 797 $ — Research and development 191 133 Other 119 90 Professional fees — 200 Total accrued expenses and other current liabilities $ 1,107 $ 423

Convertible Preferred Stock, _2

Convertible Preferred Stock, Tranche Liability and Warrant Liability (Tables)	9 Months Ended
	Sep. 30, 2021
Convertible Preferred Stock Tranche Liability and Warrant Liability [Abstract]
Summary of Convertible preferred stock	Convertible preferred stock consisted of the following as of Dec e Shares Shares Weighted Average Carrying Liquidation Series A 711,203 477,297 $ 2.24 $ 1,067 $ 1,067 Series A-1 11,898,177 7,537,879 2.24 16,333 16,847 Series B 29,457,450 11,862,043 3.80 39,253 45,070 Total 42,066,830 19,877,219 $ 56,653 $ 62,984
Summary of Assumptions Used in Estimating the Fair Value of Preferred Stock Tranche Liability	The following assumptions were used in the estimation of the fair value of the tranche liability as a forward contract as of each of the dates indicated: June 17, December 31, 2021 2020 Risk-free interest rate 0.07 % 0.12 % Expected time to Milestone Closing (in years) 0.8 1.3 Probability of achievement of Milestone Closing 100 % 65 %
Summary of Fair Value of the Warrant Liability	The following assumptions were used in the estimation of the fair value of the warrant liability using the OPM backsolve method as of each of the dates indicated: June 22, December 31, Risk-free interest rate 0.25 % 0.13 % Expected term (in years) 2.0 2.0 Expected volatility 90 % 90 % Expected dividend yield 0 % 0 %
Summary of the Tranche Liability and Warrant Liability Measured at Fair Value using Level 3 Significant Unobservable Inputs	The following table provides a reconciliation of the tranche liability and warrant liability measured at fair value using Level 3 significant unobservable inputs (in thousands): Series A-1 Series B Total Balance, December 31, 2020 $ 380 $ 5,033 $ 5,413 Change in fair value 5,000 76,157 81,157 Settlement of tranche liability due to issuance of Milestone Shares — (81,190 ) (81,190 ) Settlement of warrant liability upon exercise of warrant (5,380 ) — (5,380 ) Balance, September 30, 2021 $ — $ — $ —

Stockholders' Equity (Deficit)

Stockholders' Equity (Deficit) (Tables)	9 Months Ended
	Sep. 30, 2021
Stockholders' Equity Note [Abstract]
Summary of Outstanding Warrants to Purchase the Company's Common Stock	As of December 31, 2020, the outstanding warrants to purchase the Company’s common stock were comprised of the following: Equity Upon Exercise Expiration Dates Number of Warrants issued in 2014 Common Stock $ 4.47 3/21/2024 - 6/30/2025 83,726 Warrants issued in 2015 Common Stock $ 4.47 6/30/2025 209,690 Warrants issued in 2016 Common Stock $ 4.47 6/30/2025 34,396 Warrants issued in 2017 Common Stock $ 4.47 6/30/2025 57,881 Total Warrants 385,693

Share-Based Compensation (Table

Share-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Summary of Assumptions Used for Valuation of Fair Value of Stock Options	The Black-Scholes option-pricing model was used to estimate the fair value of stock options granted during the nine months ended September 30, 2021 with the following weighted average assumptions: Risk-free interest rate 0.4% - 1.1 % Expected term in years 5.3 - 6.1 Expected volatility 90 % Expected dividend yield 0 %
Summary of Assumptions Used for Valuation of Fair Value of Stock	As of December 31, 2020, the Company derived the fair value of its common stock with the assistance of an independent third-party valuation firm utilizing the following assumptions: Risk-free interest rate 0.13 % Expected time to liquidity event in years 2.0 Expected volatility 90 % Expected dividend yield 0 %
Summary of Stock Option Activity	The following table reflects summarized stock option activity: Stock Options Weighted Average Weighted Average Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2020 1,001,517 $ 1.13 Granted 2,663,084 2.21 Exercised (2,236 ) 0.72 Outstanding at September 30, 2021 3,662,365 $ 1.92 8.7 $ 51,591 Vested and exercisable at September 30, 2021 958,709 $ 1.38 7.1 $ 14,034 As of September 30, 2021, total unrecognized compensation costs related to unvested stock option awards granted was approximately $3.1 million, which the Company expects to recognize over a weighted-average period of approximately 3.2 years.
Summary of Share-Based Compensation Expense Related to Stock Options	T Three Months Ended Nine Months Ended 2021 2020 2021 2020 General and administrative $ 254 $ 26 $ 412 $ 78 Research and development 50 13 145 38 Total share-based compensation $ 304 $ 39 $ 557 $ 116

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Summary of Future Minimum Lease Payments	As of September 30, 2021, future minimum lease payments under this lease agreement associated with the Company’s operations were as follows (in thousands): Year ended December 31, 2021 (remaining 3 months) $ 38 Year ended December 31, 2022 153 Year ended December 31, 2023 102 Total $ 293

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
Summary of Dilutive Securities Not Included in the Diluted Net Loss Per Common Share	The table below provides potentially dilutive securities not included in the calculation of the diluted net loss per common share because to do so would be anti-dilutive: Nine Months Ended 2021 2020 Shares issuable upon conversion of Series A Preferred Stock — 477,297 Shares issuable upon conversion of Series A-1 — 7,537,879 Shares issuable upon exercise of stock options 3,662,365 1,004,898 Shares issuable upon exercise of common stock warrants — 385,693 Shares issuable upon exercise of preferred stock warrant — 447,426 Total 3,662,365 9,853,193

Description of Organization a_2

Description of Organization and Business Operations - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Jul. 08, 2021	Jul. 06, 2021	Jun. 23, 2021	Jun. 17, 2021	Nov. 20, 2020	Sep. 30, 2021	Jun. 09, 2021	Dec. 31, 2020
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Stockholders' equity, reverse stock split			1-for-1.49		1-for-30
Accumulated deficit						$ (119,222)		$ (26,965)
Working capital						$ 203,400		$ 38,100
Total number of outstanding shares increased		39,911,517
Common Stock Warrants [Member] | Common Stock [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of securities called by warrants or rights		178,847
Series A Convertible Preferred Stock [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Conversion of stock, shares converted		477,297
Series A-1 Convertible Preferred Stock [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Conversion of stock, shares converted		7,985,305
Series B Convertible Preferred Stock [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Sale of stock, number of shares issued in transaction				7,908,027
Sale of stock, price per share				$ 3.80
Conversion of stock, shares converted		19,770,070
Percentage of stockholders elected to waive achievement of milestone							67.00%
Sale of stock, consideration received on transaction				$ 30,000
IPO [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Sale of stock, number of shares issued in transaction		9,999,999
Underwriting shares	1,499,999
Sale of stock, price per share		$ 16
Sale of stock, consideration received on transaction		$ 168,600
underwriting discounts and commissions and other offering expenses		$ 15,400

Basis of Presentation, Summar_2

Basis of Presentation, Summary of Significant Accounting Policies and Recent Accounting Pronouncements - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Jul. 06, 2021	Jun. 30, 2021	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Cash equivalents			$ 134,800		$ 134,800		$ 36,800
Uncertain tax positions			$ 0		0		$ 0
Uncertain tax positions, interest or penalties recorded					$ 0	$ 0
Warrant Exercise [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 4.47
Stock Issued During Period, Shares, New Issues		137,446
Common Stock Warrants [Member]
Class of Warrant or Right, Outstanding			0		0		385,693
Common Stock [Member]
Cashless exercise of common stock warrants			178,847		178,847
Stock Issued During Period, Shares, New Issues			11,499,998		11,499,998
Common Stock [Member] | Common Stock Warrants [Member]
Cashless exercise of common stock warrants	178,847
Class of Warrant or Right, Outstanding	248,247	248,247	0		0
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 4.47
Computer Equipment [Member]
Property, Plant and Equipment, Estimated Useful Lives					three
Marketable Debt Securities [Member]
Other than temporary impairment losses, investments portion in other comprehensive loss net of tax available-for sale securities			$ 0	$ 0	$ 0	$ 0

Basis of Presentation, Summar_3

Basis of Presentation, Summary of Significant Accounting Policies and Recent Accounting Pronouncements - Summary of Fair Value Measurements, Recurring and Nonrecurring (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Assets included in:
Fair value	$ 228,872	$ 36,758
Liabilities included in:
Fair value		5,413
Commercial Paper [Member] | Marketable Debt Securities [Member]
Assets included in:
Fair value	43,923
Corporate Debt Securities [Member] | Marketable Debt Securities [Member]
Assets included in:
Fair value	24,888
Asset-backed Securities [Member] | Marketable Debt Securities [Member]
Assets included in:
Fair value	19,273
US Treasury Securities [Member] | Marketable Debt Securities [Member]
Assets included in:
Fair value	5,988
Preferred stock tranche rights liability [Member]
Liabilities included in:
Fair value		5,033
Preferred stock warrant liability [Member]
Liabilities included in:
Fair value		380
Cash and Cash Equivalents [Member] | Money Market Funds [Member]
Assets included in:
Fair value	134,800	36,758
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets included in:
Fair value	134,800	36,758
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Cash and Cash Equivalents [Member] | Money Market Funds [Member]
Assets included in:
Fair value	134,800	36,758
Significant Other Observable Inputs (Level 2) [Member]
Assets included in:
Fair value	94,072
Significant Other Observable Inputs (Level 2) [Member] | Commercial Paper [Member] | Marketable Debt Securities [Member]
Assets included in:
Fair value	43,923
Significant Other Observable Inputs (Level 2) [Member] | Corporate Debt Securities [Member] | Marketable Debt Securities [Member]
Assets included in:
Fair value	24,888
Significant Other Observable Inputs (Level 2) [Member] | Asset-backed Securities [Member] | Marketable Debt Securities [Member]
Assets included in:
Fair value	19,273
Significant Other Observable Inputs (Level 2) [Member] | US Treasury Securities [Member] | Marketable Debt Securities [Member]
Assets included in:
Fair value	$ 5,988
Significant Unobservable Inputs (Level 3) [Member]
Liabilities included in:
Fair value		5,413
Significant Unobservable Inputs (Level 3) [Member] | Preferred stock tranche rights liability [Member]
Liabilities included in:
Fair value		5,033
Significant Unobservable Inputs (Level 3) [Member] | Preferred stock warrant liability [Member]
Liabilities included in:
Fair value		$ 380

Marketable Securities - Additio

Marketable Securities - Additional Information (Details) - Marketable Debt Securities [Member] - USD ($) $ in Thousands	Sep. 30, 2021	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Marketable Securities [Line Items]
Available-for-sale securities classified as short-term maturity	one year or less
Available-for-sale securities classified as long-term maturity	two years
Other than temporary impairment losses, investments portion in other comprehensive loss net of tax available-for sale securities		$ 0	$ 0	$ 0	$ 0

Marketable Securities - Summary

Marketable Securities - Summary of Marketable securities (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2021USD ($)
Marketable Debt Securities Short Term [Member]
Marketable Securities [Line Items]
Amortized cost, Short term	$ 64,166
Gross Unrealized Loss	(4)
Fair value, Short Term	64,162
Marketable Debt Securities Long Term [Member]
Marketable Securities [Line Items]
Gross Unrealized Loss	(24)
Amortized cost, Long term	29,934
Fair value, Long Term	29,910
Marketable Debt Securities [Member]
Marketable Securities [Line Items]
Gross Unrealized Loss	(28)
Amortized Cost, Total	94,100
Fair value, Total	94,072
Commercial Paper [Member] | Marketable Debt Securities Short Term [Member]
Marketable Securities [Line Items]
Amortized cost, Short term	43,923
Fair value, Short Term	43,923
Corporate Debt Securities [Member] | Marketable Debt Securities Short Term [Member]
Marketable Securities [Line Items]
Amortized cost, Short term	8,043
Gross Unrealized Loss	(2)
Fair value, Short Term	8,041
Corporate Debt Securities [Member] | Marketable Debt Securities Long Term [Member]
Marketable Securities [Line Items]
Gross Unrealized Loss	(20)
Amortized cost, Long term	16,866
Fair value, Long Term	16,846
Asset-backed Securities [Member] | Marketable Debt Securities Short Term [Member]
Marketable Securities [Line Items]
Amortized cost, Short term	12,200
Gross Unrealized Loss	(2)
Fair value, Short Term	12,198
Asset-backed Securities [Member] | Marketable Debt Securities Long Term [Member]
Marketable Securities [Line Items]
Gross Unrealized Loss	(4)
Amortized cost, Long term	7,080
Fair value, Long Term	7,076
US Treasury Securities [Member] | Marketable Debt Securities Long Term [Member]
Marketable Securities [Line Items]
Amortized cost, Long term	5,988
Fair value, Long Term	$ 5,988

Supplemental Financial Inform_3

Supplemental Financial Information - Schedule of Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Disclosure Of Prepaid Expenses And Other Current Assets [Line Items]
Prepaid Insurance	$ 2,299	$ 5
Research and development service agreements	2,077	432
Prepaid raw materials	248	91
Other	216	15
Total prepaid expenses and other current assets	$ 4,840	$ 543

Supplemental Financial Inform_4

Supplemental Financial Information - Schedule of Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Disclosure of Accrued Expenses and Other Current Liabilities [Line Items]
Bonuses and other employee liabilities	$ 797
Research and development	191	$ 133
Other	119	90
Professional fees	0	200
Total accrued expenses and other current liabilities	$ 1,107	$ 423

Convertible Preferred Stock, _3

Convertible Preferred Stock, Tranche Liability and Warrant Liability - Additional Information (Detail)	Jul. 06, 2021shares	Jun. 17, 2021USD ($)$ / sharesshares	Sep. 30, 2021$ / sharesshares	Sep. 30, 2021USD ($)$ / sharesshares	Jun. 22, 2021$ / sharesshares	Dec. 31, 2020USD ($)$ / sharesshares	Nov. 20, 2020$ / sharesshares	Oct. 19, 2018$ / sharesshares
Convertible Preferred Stock Tranche Liability And Warrant Liability [Line Items]
Shares Issued						19,877,219
Proceeds from convertible preferred stock | $				$ 30,031,000
Temporary Equity, Shares Outstanding						19,877,219
Series A -1 Convertible Preferred Stock Warrant Liability [Member]
Convertible Preferred Stock Tranche Liability And Warrant Liability [Line Items]
Class of warrants or rights number of shares covered by warrants or rights								447,426
Class of warrants or rights term								10 years
Class of warrants or right exercise price per share | $ / shares								$ 2.794
Class of warrants or rights expiry date								Oct. 18, 2028
Fair value of warrant liability per share | $ / shares					$ 12.02	$ 0.85
Underlying Equity Value [Member] | Series B Convertible Preferred Stock Tranche Rights Liability [Member]
Convertible Preferred Stock Tranche Liability And Warrant Liability [Line Items]
Financial liabilities at fair value | $		$ 81,190,000				$ 5,033,000
Series B Redeemable Convertible Preferred Stock [Member]
Convertible Preferred Stock Tranche Liability And Warrant Liability [Line Items]
Conversion of convertible preferred stock into common stock upon initial public offering, Shares	19,770,070
Temporary Equity, Shares Outstanding		19,770,070
Series A-1 Redeemable Convertible Preferred Stock [Member]
Convertible Preferred Stock Tranche Liability And Warrant Liability [Line Items]
Shares Issued						7,537,879
Class of warrants or rights number of shares covered by warrants or rights					447,426
Class of warrants or right exercise price per share | $ / shares					$ 2.794
Conversion of convertible preferred stock into common stock upon initial public offering, Shares	7,985,305
Temporary Equity, Shares Outstanding					7,985,305	7,537,879
Series A Convertible Preferred Stock [Member]
Convertible Preferred Stock Tranche Liability And Warrant Liability [Line Items]
Shares Issued			0	0		477,297
Temporary equity par or stated value per share | $ / shares			$ 0.0001	$ 0.0001		$ 0.0001
Conversion of convertible preferred stock into common stock upon initial public offering, Shares	477,297		(477,297)	(477,297)
Temporary Equity, Shares Outstanding			0	0		477,297
Convertible Preferred Stock [Member]
Convertible Preferred Stock Tranche Liability And Warrant Liability [Line Items]
Temporary Equity, Shares Outstanding			0	0
Prospective Conversion of Temporary Equity into Permanent Equity [Member]
Convertible Preferred Stock Tranche Liability And Warrant Liability [Line Items]
Number of times the redeemable convertible preferred stock equal to the share issue price			2	2
Sale of stock issue price per share | $ / shares			$ 7.60	$ 7.60
Percentage of votes in terms of shareholding needed for conversion into permanent equity			67.00%	67.00%
Prospective Conversion of Temporary Equity into Permanent Equity [Member] | Minimum [Member]
Convertible Preferred Stock Tranche Liability And Warrant Liability [Line Items]
Proceeds from initial public offer | $				$ 75,000,000
Private Placement [Member] | Series B Redeemable Convertible Preferred Stock [Member]
Convertible Preferred Stock Tranche Liability And Warrant Liability [Line Items]
Shares Issued							19,770,070
Temporary equity par or stated value per share | $ / shares							$ 0.0001
Temporary equity issue price per share | $ / shares							$ 3.80
Private Placement [Member] | Series B Redeemable Convertible Preferred Stock [Member] | Closing of Milestone [Member]
Convertible Preferred Stock Tranche Liability And Warrant Liability [Line Items]
Temporary equity issue price per share | $ / shares		$ 3.80
Temporary equity shares issued during the period shares		7,908,027
Proceeds from convertible preferred stock | $		$ 30,000,000
Private Placement [Member] | Series B Redeemable Convertible Preferred Stock [Member] | Initial Closing [Member]
Convertible Preferred Stock Tranche Liability And Warrant Liability [Line Items]
Shares Issued							11,862,043
Private Placement [Member] | Series B Redeemable Convertible Preferred Stock [Member] | Achievement of Milestone [Member]
Convertible Preferred Stock Tranche Liability And Warrant Liability [Line Items]
Temporary equity milestone shares							7,908,027

Convertible Preferred Stock, _4

Convertible Preferred Stock, Tranche Liability and Warrant Liability - Summary of Convertible preferred stock (Detail) - USD ($) $ / shares in Units, $ in Thousands	Sep. 30, 2021	Jun. 22, 2021	Dec. 31, 2020
Temporary Equity [Line Items]
Shares Authorized			42,066,830
Shares Issued			19,877,219
Shares Outstanding			19,877,219
Carrying Value			$ 56,653
Liquidation Preference			$ 62,984
Series A
Temporary Equity [Line Items]
Shares Authorized	0		711,203
Shares Issued	0		477,297
Shares Outstanding	0		477,297
Weighted Average Issuance Price per Share			$ 2.24
Carrying Value			$ 1,067
Liquidation Preference			$ 1,067
Series A-1
Temporary Equity [Line Items]
Shares Authorized			11,898,177
Shares Issued			7,537,879
Shares Outstanding		7,985,305	7,537,879
Weighted Average Issuance Price per Share			$ 2.24
Carrying Value			$ 16,333
Liquidation Preference			$ 16,847
Series B
Temporary Equity [Line Items]
Shares Authorized	0		29,457,450
Shares Issued	0		11,862,043
Shares Outstanding	0		11,862,043
Weighted Average Issuance Price per Share			$ 3.80
Carrying Value			$ 39,253
Liquidation Preference			$ 45,070

Convertible Preferred Stock, _5

Convertible Preferred Stock, Tranche Liability and Warrant Liability - Summary of Assumptions Used in Estimating the Fair Value of Preferred Stock Tranche Liability (Detail)	Jun. 17, 2021	Dec. 31, 2020
Convertible Preferred Stock Tranche Liability and Warrant Liability [Abstract]
Risk-free interest rate	0.07%	0.12%
Expected time to Milestone Closing (in years)	9 months 18 days	1 year 3 months 18 days
Probability of achievement of Milestone Closing	100.00%	65.00%

Convertible Preferred Stock, _6

Convertible Preferred Stock, Tranche Liability and Warrant Liability - Summary of Fair Value of the Warrant Liability (Detail) - Series A -1 Convertible Preferred Stock Warrant Liability [Member]	Jun. 22, 2021yr	Dec. 31, 2020yr
Risk-free interest rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.0025	0.0013
Expected term (in years)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	2	2
Expected volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.90	0.90
Expected dividend yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0	0

Convertible Preferred Stock, _7

Convertible Preferred Stock, Tranche Liability and Warrant Liability - Summary of the Tranche Liability and Warrant Liability Measured at Fair Value using Level 3 Significant Unobservable Inputs (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2021USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, December 31, 2020	$ 5,413
Change in fair value	81,157
Settlement of tranche liability due to issuance of Milestone Shares	(81,190)
Settlement of warrant liability upon exercise of warrant	(5,380)
Balance, September 30, 2021	0
Series A-1 Preferred Stock Warrant
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, December 31, 2020	380
Change in fair value	5,000
Settlement of warrant liability upon exercise of warrant	(5,380)
Balance, September 30, 2021	0
Series B Tranche Rights
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance, December 31, 2020	5,033
Change in fair value	76,157
Settlement of tranche liability due to issuance of Milestone Shares	(81,190)
Balance, September 30, 2021	$ 0

Stockholders' Equity (Deficit_2

Stockholders' Equity (Deficit) - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	Jul. 08, 2021	Jul. 06, 2021	Jun. 30, 2021	Sep. 30, 2021	Sep. 30, 2021	Jun. 22, 2021	Dec. 31, 2020
Class of Stock [Line Items]
Common stock shares authorized				300,000,000	300,000,000		50,500,000
Temporary equity shares authorized							42,066,830
Common stock par or stated value per share		$ 0.0001		$ 0.0001	$ 0.0001		$ 0.0001
Common stock shares voting rights					one
Preferred stock, shares authorized		10,000,000		10,000,000	10,000,000		0
Total shares authorized		310,000,000
Preferred stock, par or stated value per share		$ 0.0001		$ 0.0001	$ 0.0001		$ 0.0001
Common Shares Authorized				300,000,000	300,000,000		50,500,000
Common Stock Par Value		$ 0.0001		$ 0.0001	$ 0.0001		$ 0.0001
Common Stock Warrants [Member]
Class of Stock [Line Items]
Class of Warrant or Right, Outstanding				0	0		385,693
Common Stock [Member]
Class of Stock [Line Items]
Common stock shares authorized		300,000,000
Stock issued during the period, shares				11,499,998	11,499,998
Common Shares Authorized		300,000,000
Stock Issued During Period Shares Cashless Common Stock Warrants Exercised				178,847	178,847
Common Stock [Member] | Common Stock Warrants [Member]
Class of Stock [Line Items]
Class of warrants or right exercise price per share		$ 4.47
Stock Issued During Period Shares Cashless Common Stock Warrants Exercised		178,847
Class of Warrant or Right, Outstanding		248,247	248,247	0	0
IPO [Member]
Class of Stock [Line Items]
Sale of stock, number of shares issued in transaction		9,999,999
Underwriting shares	1,499,999
Sale of stock, price per share		$ 16
underwriting discounts and commissions and other offering expenses		$ 15.4
Sale of stock, consideration received on transaction		$ 168.6
Warrant Exercise [Member]
Class of Stock [Line Items]
Stock issued during the period, shares			137,446
Class of warrants or right exercise price per share			$ 4.47
Series A Redeemable Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Temporary equity shares authorized							711,203
Series A-1 Redeemable Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Temporary equity shares authorized							11,898,177
Class of warrants or right exercise price per share						$ 2.794
Series B Redeemable Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Temporary equity shares authorized							29,457,450

Stockholders' Equity (Deficit_3

Stockholders' Equity (Deficit) - Summary of Outstanding Warrants to Purchase the Company's Common Stock (Detail) - Common Stock Warrants [Member] - $ / shares	Sep. 30, 2021	Dec. 31, 2020
Class of Warrant or Right [Line Items]
Total Warrants	0	385,693
Warrants issued in 2014 [Member]
Class of Warrant or Right [Line Items]
Exercise Price		$ 4.47
Total Warrants		83,726
Warrants issued in 2015 [Member]
Class of Warrant or Right [Line Items]
Exercise Price		$ 4.47
Expiration Dates		Jun. 30, 2025
Total Warrants		209,690
Warrants issued in 2016 [Member]
Class of Warrant or Right [Line Items]
Exercise Price		$ 4.47
Expiration Dates		Jun. 30, 2025
Total Warrants		34,396
Warrants issued in 2017 [Member]
Class of Warrant or Right [Line Items]
Exercise Price		$ 4.47
Expiration Dates		Jun. 30, 2025
Total Warrants		57,881
Minimum [Member] | Warrants issued in 2014 [Member]
Class of Warrant or Right [Line Items]
Expiration Dates		Mar. 21, 2024
Maximum [Member] | Warrants issued in 2014 [Member]
Class of Warrant or Right [Line Items]
Expiration Dates		Jun. 30, 2025

Share-Based Compensation - Addi

Share-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	Sep. 30, 2021	Sep. 30, 2021	Sep. 30, 2020	Jun. 30, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of a share of common stock				$ 16	$ 0.83
Share based compensation by share based payment arrangement unrecognized compensation costs non vested options	$ 3.1	$ 3.1
Share based compensation by share based payment arrangement unrecognized compensation costs weighted aveage period of recognition			3 years 2 months 12 days
Weighted average grant date fair value of options granted		$ 1.34
Stock options outstanding, Shares	3,662,365	3,662,365			1,001,517
2013 Amended And Restated Stock Performance Plan [Member] | Stock Options Granted Before December 31, 2017 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation by share based payment arrangement contractual term		10 years
2013 Amended And Restated Stock Performance Plan [Member] | Stock Options Granted Before December 31, 2017 [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation by share based payment arrangement vesting period		3 months
2013 Amended And Restated Stock Performance Plan [Member] | Stock Options Granted Before December 31, 2017 [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation by share based payment arrangement vesting period		24 months
2021 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grant	4,033,681	4,033,681
Share based compensation arrangement by share based payment award Cumulative annual increase in common stock shares reserved for issuance, percentage				5.00%
Share based compensation arrangement by share based payment award number of shares authorized	4,217,104	4,217,104
Common stock shares reserved for future issuance	4,033,681	4,033,681
2021 Equity Incentive Plan [Member] | Series A1 Convertible Preferred Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grant				7,698,282
Common stock shares reserved for future issuance				7,698,282
2021 Equity Incentive Plan [Member] | New Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grant				3,550,000
Common stock shares reserved for future issuance				3,550,000
2021 Equity Incentive Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum threshold common stock issuable on exercise of incentive stock options				12,000,000
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation arrangement by share based payment award Cumulative annual increase in shares reserved for issuance, percentage				1.00%
Share based compensation arrangement by share based payment award shares of common stock outstanding maximum cumulative annual increase				800,000
Stock issued during period shares employee stock purchase plans	0
Employee Stock Purchase Plan [Member] | Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance				375,000
Two Thousand And Thirteen Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options outstanding, Shares	3,478,942	3,478,942
2013 and 2021 Amended And Restated Stock Performance Plan [Member] | Stock Options Granted After December 31, 2017 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation by share based payment arrangement contractual term		10 years
2013 and 2021 Equity Incentive Plan [Member] | Stock Options Granted After December 31, 2017 [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation by share based payment arrangement vesting period		24 months
2013 and 2021 Equity Incentive Plan [Member] | Stock Options Granted After December 31, 2017 [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation by share based payment arrangement vesting period		36 months

Share-Based Compensation - Summ

Share-Based Compensation - Summary of Assumptions Used for Valuation of Fair Value of Stock (Detail)	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Black-Scholes Option-Pricing Model [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Risk-free interest rate, minimum	0.40%
Risk-free interest rate, maximum	1.10%
Expected volatility	90.00%
Expected dividend yield	0.00%
Third Party Valuation [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Risk-free interest rate		0.13%
Expected time to liquidity event in years		2 years
Expected volatility		90.00%
Expected dividend yield		0.00%
Minimum [Member] | Black-Scholes Option-Pricing Model [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Expected term in years	5 years 3 months 18 days
Maximum [Member] | Black-Scholes Option-Pricing Model [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Expected term in years	6 years 1 month 6 days

Share-Based Compensation - Su_2

Share-Based Compensation - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning balance, Stock Options	1,001,517
Options granted, Stock Options	2,663,084
Stock options exercised, Stock Options	(2,236)
Ending balance, Stock Options	3,662,365
Vested and exercisable, Stock Options	958,709
Beginning balance, Weighted Average Exercise Price	$ 1.13
Options granted, Weighted Average Exercise Price	2.21
Options Exercised, Weighted Average Exercise Price	0.72
Ending balance, Weighted Average Exercise Price	1.92
Vested and exercisable, Weighted Average Exercise Price	$ 1.38
Weighted Average Remaining Contractual Life (in years)	8 years 8 months 12 days
Vested and exercisable, Weighted Average Remaining Contractual Life (in years)	7 years 1 month 6 days
Ending balance, Aggregate Intrinsic Value	$ 51,591
Vested and exercisable, Aggregate Intrinsic Value	$ 14,034

Share-Based Compensation - Su_3

Share-Based Compensation - Summary of Share-Based Compensation Expense Related to Stock Options (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based compensation expense	$ 304	$ 39	$ 557	$ 116
General and Administrative Expense [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based compensation expense	254	26	412	78
Research and Development Expense [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Share-based compensation expense	$ 50	$ 13	$ 145	$ 38

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - New Operating Sublease [Member] - USD ($)	8 Months Ended
	Sep. 30, 2021	Feb. 01, 2021
Other Commitments [Line Items]
Operating sublease monthly rent minimum	$ 12,719
Operating sublease minimum rent obligation over the remaining term	$ 293,000
Term of operating sublease		31 months

Commitments and Contingencies_2

Commitments and Contingencies - Summary of Future Minimum Lease Payments (Detail) - New Operating Sublease [Member] $ in Thousands	Sep. 30, 2021USD ($)
Other Commitments [Line Items]
Year ended December 31, 2021 (remaining 3 months)	$ 38
Year ended December 31, 2022	153
Year ended December 31, 2023	102
Total	$ 293

Net Loss Per Share - Summary of

Net Loss Per Share - Summary of Dilutive Securities Not Included in the Diluted Net Loss Per Common Share (Detail) - shares	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Conversion of stock, shares converted	3,662,365	9,853,193
Series A Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Conversion of stock, shares converted	0	477,297
Series A1 Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Conversion of stock, shares converted	0	7,537,879
Exercise of Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Conversion of stock, shares converted	3,662,365	1,004,898
Common stock warrant [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Conversion of stock, shares converted	0	385,693
Preferred stock warrant [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Conversion of stock, shares converted	0	447,426