Xilio Therapeutics (XLO) 10-Q2 Dec 212021 Q3 Quarterly reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2021	Nov. 25, 2021
Document and Entity Information [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2021
Document Transition Report	false
Entity File Number	001-40925
Entity Registrant Name	Xilio Therapeutics, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	85-1623397
Entity Address, Address Line One	828 Winter Street
Entity Address, Address Line Two	Suite 300
Entity Address, City or Town	Waltham
Entity Address State Or Province	MA
Entity Address, Postal Zip Code	02451
City Area Code	617
Local Phone Number	430-4680
Title of 12(b) Security	Common stock, par value $0.0001 per share
Trading Symbol	XLO
Security Exchange Name	NASDAQ
Entity Current Reporting Status	No
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		27,468,948
Entity Central Index Key	0001840233
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Amendment Flag	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 99,767	$ 19,238
Prepaid expenses	2,408	1,308
Other current assets	3,397	44
Total current assets	105,572	20,590
Restricted cash	1,553	1,551
Property and equipment, net	7,108	7,367
Operating lease right-of-use asset	6,065	6,309
Other non-current assets	427	500
Total assets	120,725	36,317
Current liabilities
Accounts payable	3,822	5,444
Accrued expenses	8,194	13,732
Operating lease liability, current portion	773	564
Notes payable, current portion		2,333
Other current liabilities	82	82
Total current liabilities	12,871	22,155
Notes payable, net of current portion	9,580	7,412
Operating lease liability, net of current portion	10,316	10,908
Other liabilities, long-term	1,525	1,127
Total liabilities	34,292	41,602
Commitments and contingencies (Note 7)
Convertible preferred stock (Series A, A-1, A-2(A), A-2(A-1), B and C), $0.0001 par value, 174,808,481 shares authorized and 174,783,481 shares issued and outstanding at September 30, 2021; 133,602,056 shares authorized and 66,788,528 shares issued and outstanding at December 31, 2020; aggregate liquidation preference of $225,500 and $80,250 at September 30, 2021 and December 31, 2020, respectively	222,888	78,002
Stockholders' deficit
Common stock, $0.0001 par value; 220,400,000 shares authorized, 914,760 shares issued and 778,949 shares outstanding at September 30, 2021; 126,000,000 shares authorized, 973,898 shares issued and 689,929 shares outstanding at December 31, 2020
Additional paid-in capital	4,730	1,799
Accumulated deficit	(141,185)	(85,086)
Total stockholders' deficit	(136,455)	(83,287)
Total liabilities, convertible preferred stock and stockholders' deficit	$ 120,725	$ 36,317

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Condensed Consolidated Balance Sheets
Convertible preferred stock, par value	$ 0.0001	$ 0.0001
Convertible preferred stock, shares authorized	174,808,481	133,602,056
Convertible preferred stock, shares issued	174,783,481	66,788,528
Convertible preferred stock, shares outstanding	174,783,481	66,788,528
Convertible preferred stock, aggregate liquidation preference	$ 225,500	$ 80,250
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	220,400,000	126,000,000
Common stock, shares issued	914,760	973,898
Common stock, shares outstanding	778,949	689,929

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Operating expenses
Research and development	$ 10,470	$ 11,460	$ 39,836	$ 26,243
General and administrative	5,491	3,163	15,652	7,725
Total operating expenses	15,961	14,623	55,488	33,968
Loss from operations	(15,961)	(14,623)	(55,488)	(33,968)
Other income (expense), net
Other expense, net	(290)	(196)	(611)	(479)
Total other income (expense), net	(290)	(196)	(611)	(479)
Net loss	(16,251)	(14,819)	(56,099)	(34,447)
Comprehensive loss	$ (16,251)	$ (14,819)	$ (56,099)	$ (34,447)
Net loss per share, basic (in dollars per share)	$ (21.27)	$ (24.19)	$ (76.18)	$ (72.02)
Net loss per share, diluted (in dollars per share)	$ (21.27)	$ (24.19)	$ (76.18)	$ (72.02)
Weighted average common shares outstanding, basic (in shares)	763,869	612,657	736,416	478,283
Weighted average common shares outstanding, diluted (in shares)	763,869	612,657	736,416	478,283

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Preferred Units and Convertible Preferred Stock - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020
Temporary Equity
Beginning balance	$ 78,002
Beginning balance (in shares)	66,788,528
Series A Preferred Units
Temporary Equity
Beginning balance		$ 7,309	$ 7,309
Beginning balance (in shares)		7,500,000	7,500,000
Effect of reorganization		$ (7,309)
Effect of reorganization (in shares)		(7,500,000)
Ending balance			$ 7,309
Ending balance (in shares)			7,500,000
Series A-1 Preferred Units
Temporary Equity
Beginning balance		$ 20,740	$ 20,740
Beginning balance (in shares)		19,565,216	19,565,216
Effect of reorganization		$ (20,740)
Effect of reorganization (in shares)		(19,565,216)
Ending balance			$ 20,740
Ending balance (in shares)			19,565,216
Series B Preferred Units
Temporary Equity
Beginning balance		$ 49,953	$ 39,984
Beginning balance (in shares)		39,723,312	31,818,174
Issuance of preferred units, net of issuance costs			$ 9,969
Issuance of preferred units, net of issuance costs (in shares)			7,905,138
Effect of reorganization		$ (49,953)
Effect of reorganization (in shares)		(39,723,312)
Ending balance			$ 49,953
Ending balance (in shares)			39,723,312
Series A Convertible Preferred Stock
Temporary Equity
Beginning balance	$ 7,309
Beginning balance (in shares)	7,500,000
Effect of reorganization		$ 7,309
Effect of reorganization (in shares)		7,500,000
Ending balance	$ 7,309	$ 7,309
Ending balance (in shares)	7,500,000	7,500,000
Series A-1 Convertible Preferred Stock
Temporary Equity
Beginning balance	$ 20,740
Beginning balance (in shares)	19,565,216
Effect of reorganization		$ 20,740
Effect of reorganization (in shares)		19,565,216
Ending balance	$ 20,740	$ 20,740
Ending balance (in shares)	19,565,216	19,565,216
Series B Convertible Preferred Stock
Temporary Equity
Beginning balance	$ 49,953
Beginning balance (in shares)	39,723,312
Issuance of preferred units, net of issuance costs	$ 50,200
Issuance of preferred units, net of issuance costs (in shares)	39,723,312
Effect of reorganization		$ 49,953
Effect of reorganization (in shares)		39,723,312
Ending balance	$ 100,153	$ 49,953
Ending balance (in shares)	79,446,624	39,723,312
Series C Convertible Preferred Stock
Temporary Equity
Issuance of preferred units, net of issuance costs	$ 94,686
Issuance of preferred units, net of issuance costs (in shares)	68,271,641
Ending balance	$ 94,686
Ending balance (in shares)	68,271,641

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Preferred Units and Convertible Preferred Stock (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Series B Convertible Preferred Stock
Issuance costs	$ 50	$ 31
Series C Convertible Preferred Stock
Issuance costs	$ 314

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Common Units	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Total
Beginning balance at Dec. 31, 2019			$ 344	$ (29,867)	$ (29,523)
Beginning balance (in shares) at Dec. 31, 2019	409,303
Stockholders' Deficit
Stock-based compensation expense			96		96
Net loss				(8,118)	(8,118)
Ending balance at Mar. 31, 2020			440	(37,985)	(37,545)
Ending balance (in shares) at Mar. 31, 2020	409,303
Beginning balance at Dec. 31, 2019			344	(29,867)	(29,523)
Beginning balance (in shares) at Dec. 31, 2019	409,303
Stockholders' Deficit
Net loss					(34,447)
Ending balance at Sep. 30, 2020			1,280	(64,314)	(63,034)
Ending balance (in shares) at Sep. 30, 2020		628,632
Beginning balance at Mar. 31, 2020			440	(37,985)	(37,545)
Beginning balance (in shares) at Mar. 31, 2020	409,303
Stockholders' Deficit
Effect of reorganization (in shares)	(409,303)	409,303
Vesting of restricted common stock (in shares)		188,976
Stock-based compensation expense			151		151
Net loss				(11,510)	(11,510)
Ending balance at Jun. 30, 2020			591	(49,495)	(48,904)
Ending balance (in shares) at Jun. 30, 2020		598,279
Stockholders' Deficit
Vesting of restricted common stock (in shares)		29,326
Exercise of stock options			6		6
Exercise of stock options (in shares)		1,027
Stock-based compensation expense			683		683
Net loss				(14,819)	(14,819)
Ending balance at Sep. 30, 2020			1,280	(64,314)	(63,034)
Ending balance (in shares) at Sep. 30, 2020		628,632
Beginning balance at Dec. 31, 2020			1,799	(85,086)	(83,287)
Beginning balance (in shares) at Dec. 31, 2020		689,929
Stockholders' Deficit
Vesting of restricted common stock (in shares)		27,989
Exercise of stock options			24		24
Exercise of stock options (in shares)		4,473
Stock-based compensation expense			794		794
Net loss				(16,668)	(16,668)
Ending balance at Mar. 31, 2021			2,617	(101,754)	(99,137)
Ending balance (in shares) at Mar. 31, 2021		722,391
Beginning balance at Dec. 31, 2020			1,799	(85,086)	$ (83,287)
Beginning balance (in shares) at Dec. 31, 2020		689,929
Stockholders' Deficit
Exercise of stock options (in shares)					8,092
Net loss					$ (56,099)
Ending balance at Sep. 30, 2021			4,730	(141,185)	(136,455)
Ending balance (in shares) at Sep. 30, 2021		778,949
Beginning balance at Mar. 31, 2021			2,617	(101,754)	(99,137)
Beginning balance (in shares) at Mar. 31, 2021		722,391
Stockholders' Deficit
Vesting of restricted common stock (in shares)		26,676
Exercise of stock options			6		6
Exercise of stock options (in shares)		1,034
Stock-based compensation expense			1,002		1,002
Net loss				(23,180)	(23,180)
Ending balance at Jun. 30, 2021			3,625	(124,934)	(121,309)
Ending balance (in shares) at Jun. 30, 2021		750,101
Stockholders' Deficit
Vesting of restricted common stock (in shares)		26,263
Exercise of stock options			14		14
Exercise of stock options (in shares)		2,585
Stock-based compensation expense			1,091		1,091
Net loss				(16,251)	(16,251)
Ending balance at Sep. 30, 2021			$ 4,730	$ (141,185)	$ (136,455)
Ending balance (in shares) at Sep. 30, 2021		778,949

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities:
Net loss	$ (56,099)	$ (34,447)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,105	724
Non-cash interest expense	121	(2)
Equity-based compensation expense	2,887	930
Loss on disposal of property and equipment	19
Change in fair value of warrant and derivative liabilities	199	431
Changes in operating assets and liabilities:
Prepaid and other assets	(3,597)	2,802
Operating lease right-of-use asset	244	224
Accounts payable	(1,626)	338
Accrued expenses and other liabilities	(6,459)	5,743
Operating lease liability	(383)	(129)
Net cash used in operating activities	(63,589)	(23,386)
Cash flows from investing activities:
Purchases of property and equipment	(722)	(2,080)
Net cash used in investing activities	(722)	(2,080)
Cash flows from financing activities:
Repayments of debt principal	(1,000)
Proceeds from debt issuance, net of issuance costs	975
Proceeds from issuance of Series B preferred units, net of issuance costs		9,969
Payments of finance lease	(63)	(71)
Proceeds from exercise of stock options	44	6
Net cash provided by financing activities	144,842	9,904
Increase (decrease) in cash, cash equivalents & restricted cash	80,531	(15,562)
Cash, cash equivalents and restricted cash, beginning of period	20,789	49,039
Cash, cash equivalents and restricted cash, end of period	101,320	33,477
Supplemental cash flow disclosure:
Cash paid for interest	371	410
Supplemental disclosure of non-cash activities:
Right-of-use assets obtained in exchange for operating lease liabilities		39
Right-of-use assets obtained in exchange for finance lease liabilities		423
Tenant improvements funded by landlord		2,827
Capital expenditures included in accounts payable or accrued expenses	47	$ 30
Deferred offering costs included in accounts payable or accrued expenses	879
Recognition of derivative liability in connection with long-term debt facility	250
Series B Convertible Preferred Stock
Cash flows from financing activities:
Proceeds from issuance preferred units, net of issuance costs	50,200
Series C Convertible Preferred Stock
Cash flows from financing activities:
Proceeds from issuance preferred units, net of issuance costs	$ 94,686

Description of Business, Organi

Description of Business, Organization and Liquidity	9 Months Ended
Description of Business, Organization and Liquidity	Sep. 30, 2021
Description of Business, Organization and Liquidity
Description of Business, Organization and Liquidity	1. Description of Business, Organization and Liquidity Description of Business Xilio Therapeutics, Inc., incorporated in Delaware in June 2020, is a biotechnology company focused on harnessing the immune system to achieve deep and durable clinical responses to improve the lives of patients with cancer. For purposes of these condensed consolidated financial statements, the “Company” refers to Xilio Therapeutics LLC (formerly Akriveia Therapeutics Inc., Akriveia Therapeutics LLC and Akrevia Therapeutics LLC) prior to the reorganization described below, and Xilio Therapeutics, Inc. after such reorganization. The Company’s headquarters are based in Waltham, Massachusetts. Organization Akriveia Therapeutics Inc. was incorporated in Delaware in June 2015. In May 2016, Akriveia Therapeutics Inc. completed its first tax free reorganization, and the parent entity became Akriveia Therapeutics LLC. Akriveia Therapeutics LLC subsequently changed its name to Akrevia Therapeutics LLC in May 2018 and then to Xilio Therapeutics LLC in February 2020. In June 2020, the Company completed a series of transactions pursuant to which Xilio Therapeutics LLC became a direct, wholly owned subsidiary of Xilio Therapeutics, Inc., and all of the outstanding membership interests of Xilio Therapeutics LLC were exchanged for equity securities of Xilio Therapeutics, Inc. and Xilio Therapeutics, Inc. became the parent entity (the “Reorganization”). The purpose of the transaction was to reorganize the corporate structure so that existing investors would own capital stock in a corporation rather than equity interests in a limited liability company. Upon consummation of the Reorganization, the historical consolidated financial statements of Xilio Therapeutics LLC became the historical consolidated financial statements of Xilio Therapeutics, Inc. Liquidity Since inception, the Company has devoted substantially all of its financial resources and efforts to research and development activities. The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry, including but not limited to, risks associated with completing research programs and conducting additional research programs, advancing the Company’s current and future product candidates into preclinical and clinical development, seeking marketing approvals for any product candidates that successfully complete clinical trials, obtaining, expanding, maintaining and defending the Company’s intellectual property, and hiring additional clinical, regulatory, and scientific personnel. Programs currently under development will require significant additional research and development efforts, including preclinical and clinical testing and will need to obtain regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel and infrastructure and extensive compliance-reporting capabilities. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will realize revenue from product sales. On October 26, 2021, the Company completed its initial public offering (“IPO”) of common stock and issued and sold an aggregate of 7,353,000 shares of its common stock at a public offering price of $16.00 per share, and on November 1, 2021, the Company issued and sold an additional 766,106 shares of common stock at a public offering price of $16.00 per share pursuant to the exercise by the underwriters of their option to purchase additional shares. The Company received aggregate gross proceeds of approximately $129.9 million or aggregate net proceeds of approximately $116.3 million, after deducting underwriting discounts and commissions and estimated offering expenses payable by the Company. Upon the closing of the IPO, all shares of the Company’s then outstanding preferred stock automatically converted into an aggregate of 18,398,248 shares of common stock (see Note 8). Prior to its IPO, the Company had primarily funded its operations with proceeds from the sale of convertible preferred units and convertible preferred stock and a debt financing. As of September 30, 2021, the Company had cash and cash equivalents of $99.8 million. The Company expects that its cash and cash equivalents, including the net proceeds from the IPO, will be sufficient to meet the Company’s projected operating requirements and capital expenditures for at least twelve months from the date of issuance of these condensed consolidated financial statements. The Company expects to continue to generate negative cash flows from operations and net losses for the foreseeable future as it continues to invest significantly in research and development of its product candidates, including preclinical, clinical and manufacturing process development. Management’s conclusion with respect to its ability to fund operations is based on estimates that are subject to risks and uncertainties that may prove to be incorrect. If actual results differ from management’s estimates, the Company may be required to seek additional funding or curtail planned activities to reduce operating expenses, which may have an adverse impact on the Company’s ability to achieve its business objectives.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
Summary of Significant Accounting Policies	Sep. 30, 2021
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation These condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”) and pursuant to the rules and regulations of the United States Securities and Exchange Commission, (the “SEC”). Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASUs”) of the Financial Accounting Standards Board (“FASB”). In April 2012, the Jumpstart Our Business Startups Act of 2012 (the “JOBS Act”) was enacted. Section 107(b) of the JOBS Act provides that an emerging growth company can take advantage of an extended transition period for complying with new or revised accounting standards. Thus, an emerging growth company can delay the adoption of certain accounting standards until those standards would otherwise apply to private companies. The Company has elected not to “opt out” of such extended transition period, which means that when a standard is issued or revised and it has different application dates for public or private companies, the Company can adopt the new or revised standard at the time private companies adopt the new or revised standard and may do so until such time that the Company either (1) irrevocably elects to “opt out” of such extended transition period or (2) no longer qualifies as an emerging growth company. The Company may take advantage of these exemptions up until the last day of the fiscal year following the fifth anniversary of its initial public offering or such earlier time that it is no longer an emerging growth company. The Company’s significant accounting policies are disclosed in the audited consolidated financial statements included in the Company’s final prospectus for its IPO, dated October 22, 2021, and filed with the SEC, pursuant to Rule 424(b)(4) under the Securities Act of 1933, as amended (the “Prospectus”). Since the date of such audited consolidated financial statements, there have been no changes to the Company’s significant accounting policies except as noted below. Unaudited Interim Condensed Consolidated Financial Information The accompanying condensed consolidated balance sheet as of September 30, 2021, the condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2021 and 2020, the statements of cash flows for the nine months ended September 30, 2021 and 2020 and the condensed consolidated statements of preferred units and convertible preferred stock and members’ and stockholders’ deficit for the nine months ended September 30, 2021 and 2020 are unaudited. The financial data and other information contained in the notes thereto as of and for the three and nine months ended September 30, 2021 and 2020 are also unaudited. The condensed consolidated balance sheet data as of December 31, 2020 was derived from the Company’s audited consolidated financial statements included in the Prospectus. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited annual consolidated financial statements, and in the opinion of management, reflect all adjustments, which include only normal recurring adjustments necessary for the fair presentation of the Company’s financial position as of September 30, 2021, the results of its operations for the three and nine months ended September 30, 2021 and 2020 and cash flows for the nine months ended September 30, 2021 and 2020. These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements as of and for the year ended December 31, 2020, and the notes thereto, included in the Prospectus. The results for the three and nine months ended September 30, 2021 are not necessarily indicative of results to be expected for the year ended December 31, 2021, or any other interim periods, or any future year or period. Use of Estimates The preparation of financial statements in accordance with GAAP requires management to make estimates and judgments that may affect the reported amounts of assets and liabilities and related disclosures of contingent assets and liabilities at the date of the financial statements and the related reporting of expenses during the reporting period. Management considers many factors in selecting appropriate financial accounting policies and controls, and in developing the estimates and assumptions that are used in the preparation of these condensed consolidated financial statements. Factors that may affect estimates, include expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes and management must select an amount that falls within that range of reasonable estimates. Significant estimates of accounting reflected in these condensed consolidated financial statements include, but are not limited to, estimates related to accrued expenses, contingent liabilities associated with the consummation of specified transactions, including an initial public offering, the valuation of equity-based compensation, including incentive units, stock options and restricted common stock, and income taxes. Actual results could differ from those estimates. Cash Equivalents and Restricted Cash The Company considers all short-term, highly liquid investments with original maturities of 90 days or less at acquisition date to be cash equivalents. Cash equivalents, which consist of money market accounts, are stated at fair value. Restricted cash primarily represents a letter of credit issued to the landlord of the Company’s facility lease and is reflected in non-current assets on the accompanying condensed consolidated balance sheets. Cash, cash equivalents and restricted cash consists of the following (in thousands): September 30, December 31, 2021 2020 Cash and cash equivalents $ 99,767 $ 19,238 Restricted cash 1,553 1,551 Total cash, cash equivalents and restricted cash as shown on the condensed consolidated statement of cash flows $ 101,320 $ 20,789 Deferred Offering Costs The Company capitalizes certain legal, professional, accounting and other third-party fees that are directly associated with in-process equity financings as deferred offering costs until the related financings are consummated. After consummation of the equity financing, such costs are reclassified as a reduction to additional paid-in capital generated as a result of the related financing. Should an in-process equity financing be abandoned, the deferred offering costs will be expensed immediately and accounted for as operating expenses in the condensed consolidated statements of operations and comprehensive loss. Deferred offering costs are presented as a component of other current assets on the condensed consolidated balance sheets. As of September 30, 2021, the Company capitalized $3.4 million of deferred offering costs related to its IPO. There were no deferred offering costs as of December 31, 2020. Comprehensive Loss Comprehensive loss is the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. Comprehensive loss includes net loss and the change in accumulated other comprehensive loss for the period. The Company did not have any items of comprehensive loss other than its net loss for the three and nine months ended September 30, 2021 and 2020. Equity-Based Compensation The Company utilizes significant estimates and assumptions in determining the fair value of its equity and equity-based awards. Beginning in the nine months ended September 30, 2021, the Company determined the fair value of shares of its common stock underlying stock-based awards granted using a hybrid approach. The hybrid approach is a scenario-based analysis and where one or more of the scenarios allocate the equity value utilizing the option-pricing method (“OPM”). When using the hybrid approach, the Company estimates the probability-weighted value across multiple scenarios but used the OPM to estimate the allocation of value within at least one of the scenarios. In addition to a scenario using the OPM, the hybrid method also considers an initial public offering scenario in which the shares of convertible preferred stock are assumed to convert to common stock. The future value of the common stock in the initial public offering scenario was discounted back to the valuation date at an appropriate risk adjusted discount rate. In the hybrid method, the present value indicated for each scenario was probability weighted to arrive at an indication of value for the Company’s common stock. Recently Adopted Accounting Pronouncements The Company did not adopt any new accounting standards during the nine-month period ended September 30, 2021. The Company continues to evaluate accounting standards that were recently issued but not yet adopted as of September 30, 2021.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
Fair Value Measurements	Sep. 30, 2021
Fair Value Measurements
Fair Value Measurements	3. Fair Value Measurements The Company measures the following financial liabilities at fair value on a recurring basis. The fair value of these liabilities was determined as follows (in thousands): Quoted Prices in Active Significant Markets for Other Significant Identical Observable Unobservable September 30, Assets Inputs Inputs 2021 Level 1 Level 2 Level 3 Financial liabilities: Debt derivative liability $ 750 $ — $ — $ 750 Other derivative liability 500 — — 500 Warrant to purchase Series A convertible preferred stock 25 — — 25 Total financial liabilities $ 1,275 $ — $ — $ 1,275 Quoted Prices in Active Significant Markets for Other Significant Identical Observable Unobservable December 31, Assets Inputs Inputs 2020 Level 1 Level 2 Level 3 Financial liabilities: Debt derivative liability $ 396 $ — $ — $ 396 Other derivative liability 407 — — 407 Warrant to purchase Series A convertible preferred stock 22 — — 22 Total financial liabilities $ 825 $ — $ — $ 825 During the nine months ended September 30, 2021 and the year ended December 31, 2020, the Company did not hold any investments and there were no transfers between Level 1, Level 2, and Level 3. The fair value of the warrant liability is calculated utilizing the Black-Scholes option-pricing model and contains significant inputs not observable in the market, which represents a Level 3 measurement within the fair value hierarchy. The fair values of the debt derivative liability and the other derivative liability that are contingently payable upon the consummation of specified transactions, including an initial public offering, are based on significant inputs not observable in the market, including estimates regarding the probability of certain potential future events and outcomes and estimates regarding timing of those events and outcomes, with an applied discount rate representative of time value which represents a Level 3 measurement within the fair value hierarchy. The following table summarizes the changes in the fair market value of the Company’s warrant liability, debt derivative liability and other derivative liability, which are classified within the Level 3 fair value hierarchy (in thousands): Total Debt Other level 3 Warrant derivative derivative financial liability liability liability liabilities Balance at December 31, 2020 $ 22 $ 396 $ 407 $ 825 Change in fair value of liability 3 354 93 450 Balance at September 30, 2021 $ 25 $ 750 $ 500 $ 1,275 As discussed further in Note 6, the change in fair value of the debt derivative liability includes the impact of an amendment to the loan and security agreement with Pacific Western Bank (“PacWest”) in September 2021, which resulted in the increase of the one-time fee the Company was obligated to pay to PacWest upon the occurrence of specified liquidation events, including an initial public offering, from $0.5 million to $0.8 million.

Property and Equipment, Net

Property and Equipment, Net	9 Months Ended
Property and Equipment, Net	Sep. 30, 2021
Property and Equipment, Net
Property and Equipment, Net	4. Property and Equipment, Net Property and equipment, net consists of the following (in thousands): September 30, December 31, 2021 2020 Laboratory equipment $ 3,490 $ 2,925 Computers and software 228 228 Furniture and fixtures 636 482 Leasehold improvements 5,092 5,092 Construction in process 15 — Total property and equipment $ 9,461 $ 8,727 Less accumulated depreciation (2,353) (1,360) Property and equipment, net $ 7,108 $ 7,367 The Company incurred depreciation and amortization expense related to property and equipment, net of $1.0 million and $0.7 million for the nine months ended September 30, 2021 and 2020, respectively.

Accrued Expenses

Accrued Expenses	9 Months Ended
Accrued Expenses	Sep. 30, 2021
Accrued Expenses
Accrued Expenses	5. Accrued Expenses Accrued expenses consist of the following (in thousands): September 30, December 31, 2021 2020 External research and development $ 3,238 $ 11,060 Personnel related 3,100 2,013 Professional services 1,569 481 Other 287 178 Total accrued expenses $ 8,194 $ 13,732

Loan and Security Agreement

Loan and Security Agreement	9 Months Ended
Loan and Security Agreement	Sep. 30, 2021
Loan and Security Agreement
Loan and Security Agreement	6. Loan and Security Agreement Initial Loan Agreement In November 2019, the Company entered into a loan and security agreement with PacWest, as amended by a first amendment, dated March 12, 2021, and a second amendment, dated May 10, 2021 (the “Initial Loan Agreement”). Pursuant to the Initial Loan Agreement, the Company borrowed $10.0 million under a term loan. Interest on the outstanding initial loan balance accrued at a variable annual rate equal to the greater of (i) the prime rate, as defined in the Loan Agreement, plus 0.25% or (ii) 5.00%. The Company was required to make interest only payments on the loan on a monthly basis through May 21, 2021. Subsequent to the interest-only period, the Company was required to make equal monthly payments of principal plus interest until the scheduled loan maturity on November 21, 2023. In addition, under the Initial Loan Agreement, the Company was obligated to pay a one-time $0.5 million fee to PacWest upon the occurrence of specified liquidation events, including an initial public offering. The fee represented a derivative instrument that the Company bifurcated from the debt arrangement and carried at fair value with any changes in such fair value recorded to other income (expense), net in the Company’s consolidated statements of operations and comprehensive loss. This debt derivative is recorded as a component of other liabilities, long-term on the Company’s condensed consolidated balance sheets. Upon the closing of the loan, the fair value of the debt derivative liability was $0.4 million that, together with certain legal and other fees incurred by the Company and associated with the Loan Agreement, was recognized as a debt discount and reflected as a reduction in the carrying value of the debt. The debt discount has been accreted and recognized as additional interest expense over the term of the Loan Agreement using the effective interest method. Amended Loan Agreement On September 17, 2021, the Company entered into a third amendment to the Initial Loan Agreement (as amended, the “Amended Loan Agreement” and together with the Initial Loan Agreement, the “Loan Agreement”), pursuant to which the Company borrowed $10.0 million under a new term loan and used the proceeds of such new term loan to repay the outstanding balance on the prior term loan. In addition, as a result of the amendment, prior to December 31, 2022, the Company has the ability to request one or more additional term loans in an aggregate principal amount of $10.0 million. Interest on amounts outstanding under the Loan Agreement accrued at a variable annual rate equal to the greater of (i) the prime rate plus 0.25% or (ii) 4.75%. As a result of the amendment, the Company is required to make interest-only payments on any outstanding balances through December 31, 2022. Subsequent to the interest-only period, the Company will be required to make equal monthly payments of principal plus interest until the loan matures on June 30, 2024. In addition, under the Amended Loan Agreement, the one-time fee the Company was obligated to pay to PacWest upon the occurrence of specified liquidation events, including an initial public offering, was increased from $0.5 million to an amount between $0.8 million and $1.0 million, depending on the timing and occurrence of specified events, including the closing of the IPO. The Company paid the one-time fee of $0.8 million to PacWest in October 2021 upon the closing of the IPO. As a result of the amendment, the Company is also obligated to pay PacWest a fee of 1.0% of the aggregate principal amounts then outstanding if any term loans are repaid prior to September 17, 2022. Using the net present value method, the Company concluded the amendment should be accounted for as a debt modification as the present value of the remaining cash flows of the amended term loan are not substantially different from the present value of the remaining cash flows of the initial term loan. The Loan Agreement contains customary representations, warranties and covenants and also includes customary terms covering events of default, including payment defaults, breaches of covenants, a change of control provision and occurrence of a material adverse effect. As security for its obligations under the Loan Agreement, the Company granted PacWest a first priority security interest on substantially all of the Company’s assets (other than intellectual property), subject to certain exceptions. The Company has determined that the risk of subjective acceleration under the material adverse effect clause is not probable and therefore has classified the long-term portion of the outstanding principal in non-current liabilities. Upon the occurrence and continuation of an event of default, a default interest rate of an additional 5% per annum may be applied to the outstanding loan balance, and the administrative agent, collateral agent, and lender may declare all outstanding obligations immediately due and payable and exercise all of their rights and remedies as set forth in the Loan Agreement and under applicable law. As of September 30, 2021, the Company was in compliance with all covenants under the Loan Agreement. The Company has the following minimum aggregate future loan payments under the Loan Agreement at September 30, 2021 (in thousands): Minimum Loan Payments 2021 $ — 2022 — 2023 6,667 2024 3,333 Total future principal payments 10,000 Less: unamortized discount (420) Total notes payable $ 9,580 During the nine months ended September 30, 2021 and September 30, 2020, the Company recognized $0.5 million and $0.4 million of interest expense related to the Loan Agreement, which is reflected in other expense on the consolidated statements of operations and comprehensive loss.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Sep. 30, 2021
Commitments and Contingencies
Commitments and Contingencies	7. Commitments and Contingencies Leases The Company has an operating lease for its facility and a finance lease for certain lab equipment. As of September 30, 2021, the Company has a letter of credit for the benefit of its landlord in the amount of $1.6 million, collateralized by a money market fund. Legal Proceedings From time to time, the Company may be party to legal proceedings or litigation arising in the ordinary course of business. The Company was not subject to any material legal proceedings during the nine months ended September 30, 2021 or during the year ended December 31, 2020. Guarantees and Indemnifications In the ordinary course of business, the Company enters into agreements that may include indemnification provisions. Pursuant to such agreements, the Company may indemnify, hold harmless and defend an indemnified party for losses suffered or incurred by the indemnified party. Some of the provisions will limit losses to those arising from third-party actions. In some cases, the indemnification will continue after the termination of the agreement. The maximum potential amount of future payments the Company could be required to make under these provisions is not determinable. The Company has never incurred material costs to defend lawsuits or settle claims related to these indemnification provisions. In addition, the Company has entered into indemnification agreements with members of its board of directors and executive officers that may require the Company, among other things, to indemnify them against liabilities that may arise by reason of their status or service as directors or officers. The Company maintains a general liability insurance policy that covers certain liabilities of its directors and officers arising out of claims based on acts or omissions in their capacities as directors or officers.

Convertible Preferred Stock and

Convertible Preferred Stock and Common Stock	9 Months Ended
Convertible Preferred Stock and Common Stock	Sep. 30, 2021
Convertible Preferred Stock and Common Stock
Convertible Preferred Stock and Common Stock	8. Convertible Preferred Stock and Common Stock Convertible Preferred Stock As of December 31, 2020, the Company had authorized 133,602,056 shares of convertible preferred stock, which consisted of the following: 7,525,000 shares of Series A convertible preferred stock, 19,565,216 shares of Series A-1 convertible preferred stock, 7,500,000 shares of Series A-2(A) convertible preferred stock, 19,565,216 shares of Series A-2(A-1) convertible preferred stock, and 79,446,624 shares of Series B convertible preferred stock. On January 20, 2021, the Company issued 39,723,312 shares of Series B convertible preferred stock to existing Series B convertible preferred stockholders at $1.265 per share for cash proceeds of $50.2 million, net of issuance costs. On February 22, 2021, the Company amended and restated its certificate of incorporation to authorize 174,808,481 shares of Convertible Preferred Stock, of which 7,525,000 shares are designated as Series A convertible preferred stock, 19,565,216 shares are designated as Series A-1 convertible preferred stock, 79,446,624 shares are designated as Series B convertible preferred stock, and 68,271,641 shares are designated as Series C convertible preferred stock. On February 23, 2021, the Company entered into a stock purchase agreement with existing and new investors whereby the Company issued and sold 68,271,641 shares of Series C convertible preferred stock to investors at $1.3915 per share for cash proceeds of $94.7 million, net of issuance costs. The Company has evaluated the convertible preferred stock and determined that they should be considered an “equity host” and not a “debt host.” The evaluation was necessary to determine if any embedded features required bifurcation and separate accounting as a derivative financial instrument. The Company’s analysis was based on a consideration of the economic characteristics and risks and more specifically, evaluated all the stated and implied substantive terms and features including (i) whether the convertible preferred stock included redemption features, (ii) how and when any redemption features could have been exercised, (iii) whether the convertible preferred stock were entitled to dividends, (iv) the voting rights of the convertible preferred stock and (v) the existence and nature of any conversion rights. As a result of its evaluation that the convertible preferred stock is an “equity host,” the various embedded conversion options are not considered a separate, embedded derivative. The Company’s convertible preferred stock (collectively, the “Convertible Preferred Stock”) consisted of the following (in thousands, except share amounts): As of September 30, 2021 Common Preferred Shares Preferred Shares Issuable Shares Issued and Carrying Liquidation Upon Authorized Outstanding Value Preference Conversion Series A convertible preferred stock 7,525,000 7,500,000 $ 7,309 $ 7,500 789,473 Series A‑1 convertible preferred stock 19,565,216 19,565,216 20,740 22,500 2,059,496 Series B convertible preferred stock 79,446,624 79,446,624 100,153 100,500 8,362,793 Series C convertible preferred stock 68,271,641 68,271,641 94,686 95,000 7,186,486 174,808,481 174,783,481 $ 222,888 $ 225,500 18,398,248 As of December 31, 2020 Preferred Shares Common Shares Preferred Shares Issued and Carrying Liquidation Issuable Upon Authorized Outstanding Value Preference Conversion Series A convertible preferred stock 7,525,000 7,500,000 $ 7,309 $ 7,500 789,473 Series A‑1 convertible preferred stock 19,565,216 19,565,216 20,740 22,500 2,059,496 Series A‑2(A) convertible preferred stock 7,500,000 — — — — Series A‑2(A‑1) convertible preferred stock 19,565,216 — — — — Series B convertible preferred stock 79,446,624 39,723,312 49,953 50,250 4,181,390 133,602,056 66,788,528 $ 78,002 $ 80,250 7,030,359 Upon the closing of the IPO in October 2021, all shares of the Company’s then outstanding preferred stock automatically converted into an aggregate of 18,398,248 shares of common stock. Common Stock As of September 30, 2021 and December 31, 2020, the Company’s certificate of incorporation, as amended, authorized the Company to issue 220,400,000 and 126,000,000 shares of common stock, $0.0001 par value per share, respectively. Shares Reserved for Future Issuance The Company had reserved shares of common stock for the conversion of outstanding Convertible Preferred Stock and for future issuance under the 2020 Stock Incentive Plan (as amended, the “2020 Plan”) as of the following dates: September 30, December 31, 2021 2020 Shares of common stock reserved for conversion of convertible preferred stock outstanding 18,398,248 7,030,359 Shares of common stock reserved for conversion of convertible preferred shares issuable upon exercise of a warrant 2,631 2,631 Shares of common stock reserved for exercise of outstanding stock options under the 2020 Stock Incentive Plan 3,391,136 810,358 Shares of common stock reserved for future awards under the 2020 Stock Incentive Plan 429,109 151,769 Total shares reserved for future issuance 22,221,124 7,995,117

Equity-Based Compensation

Equity-Based Compensation	9 Months Ended
Equity-Based Compensation	Sep. 30, 2021
Equity-Based Compensation
Equity-Based Compensation	9. Equity-Based Compensation Equity Incentive Plans During the nine months ended September 30, 2021, the Company amended its 2020 Plan to increase the common stock issuable under the plan from 991,021 shares to 3,773,235 shares, plus up to 364,120 of additional shares of common stock equal to the number of shares of unvested restricted stock issued in exchange for incentive units as part of the Reorganization, to the extent such shares have been or will be forfeited. Restricted Stock A summary of the Company’s restricted stock activity and related information is as follows: Number Weighted of Shares Average of Restricted Grant Date Stock Fair Value Unvested as of December 31, 2020 283,969 $ 5.51 Vested (80,928) 5.51 Canceled/Forfeited (67,230) 5.51 Unvested as of September 30, 2021 135,811 5.51 The Company had granted 552,546 shares of common stock underlying restricted stock awards as of June 30, 2020 in connection with the Reorganization. During the nine months ended September 30, 2021, the aggregate fair value of the restricted stock awards that vested was $0.7 million. As of September 30, 2021, total unrecognized compensation cost related to unvested restricted stock awards was approximately $0.8 million, which is expected to be recognized over a weighted-average period of 1.98 years. Stock Options A summary of stock option activity under the 2020 Plan is as follows: Weighted Average Remaining Aggregate Weighted Contractual Intrinsic Number of Average Term Value Stock Options Exercise Price (In years) (In thousands) Outstanding as of December 31, 2020 810,358 $ 5.51 9.52 $ — Granted 2,993,919 7.32 Exercised (8,092) 5.55 Cancelled/forfeited (405,049) 6.17 Outstanding as of September 30, 2021 3,391,136 7.03 9.14 $ 15,795 Exercisable as of September 30, 2021 555,282 5.84 7.63 $ 3,243 Vested and expected to vest as of September 30, 2021 3,391,136 7.03 9.14 $ 15,795 Using the Black-Scholes option pricing model, the weighted average fair value of options granted to employees and directors during the nine months ended September 30, 2021 and 2020 was $5.16 and $3.60. The following assumptions were used in determining the fair value of options granted to employees during the nine months ended September 30, 2021 and 2020: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Risk-free interest rate 0.92 – 0.93 % 0.16 – 0.36 % 0.63 – 1.15 % 0.16 – 0.36 % Expected dividend yield 0 % 0 % 0 % 0 % Expected term (in years) 6.00 – 6.08 2.25 – 6.08 5.52 – 10.00 2.25 – 6.08 Expected volatility 80.60 – 80.76 % 78.84 –96.73 % 80.60 – 85.26 % 78.84 –96.73 % The achievement of the performance conditions underlying outstanding performance-based awards was not probable as of September 30, 2021; therefore, no compensation expense was recorded for these awards. As of September 30, 2021, total unrecognized compensation costs related to performance-based awards was $0.5 million. As of September 30, 2021, total unrecognized compensation cost related to unvested stock options, excluding performance-based awards, was approximately $13.1 million, which is expected to be recognized over a weighted-average period of 3.22 years. During the nine months ended September 30, 2021, the Company entered into separation agreements with two former employees. Pursuant to the separation agreements, the former employees terminated their employment with the Company and agreed to provide certain consulting services to the Company through October 15, 2021 and November 30, 2021, respectively, during which the former employees’ equity awards will continue to vest. In addition, the Company extended the former employees’ periods to exercise their vested option until 90 days from the termination date of the respective consulting periods. Because the services to be performed during the consulting period are considered non-substantive, the Company concluded that the former employees’ equity awards were modified. As a result of these modifications, the Company recognized $0.2 million in equity-based compensation expense in the statement of operations and comprehensive loss during the nine months ended September 30, 2021. Equity-Based Compensation Expense During the three and nine months ended September 30, 2021 and 2020, the Company recorded compensation expense related to incentive units, stock options, and restricted common stock for employees and non-employees, which was allocated as follows in the condensed consolidated statements of operations and comprehensive loss (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Research and development expense $ 378 $ 183 $ 864 $ 240 General and administrative expense 713 500 2,023 690 Total equity-based compensation expense $ 1,091 $ 683 $ 2,887 $ 930

Income Taxes

Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 2021
Income Taxes
Income Taxes	10. Income Taxes The Company did not record a provision or benefit for income taxes during the nine months ended September 30, 2021 and 2020. The Company continues to maintain a full valuation allowance against all of its deferred tax assets. The Company has evaluated the positive and negative evidence involving its ability to realize its deferred tax assets and has considered its history of cumulative net losses incurred since inception and its lack of any commercially ready products. The Company has concluded that it is more likely than not that it will not realize the benefits of its deferred tax assets. The Company reevaluates the positive and negative evidence at each reporting period.

Net Loss Per Share

Net Loss Per Share	9 Months Ended
Net Loss Per Share	Sep. 30, 2021
Net Loss Per Share
Net Loss Per Share	11. Net Loss Per Share The following table sets forth the outstanding shares of common stock equivalents, presented based on amounts outstanding at each period end, that were excluded from the calculation of diluted net loss per share attributable to common stockholders during each period because including them would have been anti-dilutive: Nine Months Ended September 30, 2021 2020 Convertible preferred stock 18,398,248 7,030,359 Unvested restricted common stock 135,811 331,607 Outstanding stock options 3,391,136 854,978 Warrants 2,631 2,631 Total common stock equivalents 21,927,826 8,219,575

Subsequent Events

Subsequent Events	9 Months Ended
Subsequent Events	Sep. 30, 2021
Subsequent Events.
Subsequent Events	12. Subsequent Events Reverse Stock Split The Company’s board of directors and stockholders approved an amendment to the Company’s certificate of incorporation, which became effective on October 15, 2021. The amendment effected a 1 Initial Public Offering On October 26, 2021, the Company completed its IPO and issued and sold an aggregate of 7,353,000 shares of its common stock at a public offering price of $16.00 per share, and on November 1, 2021, the Company issued and sold an additional 766,106 shares of common stock at a public offering price of $16.00 per share pursuant to the exercise by the underwriters of their option to purchase additional shares. The Company received aggregate gross proceeds of approximately $129.9 million or aggregate net proceeds of approximately $116.3 million, after deducting underwriting discounts and commissions and estimated offering expenses payable by the Company. Upon the closing of the IPO, all shares of the Company’s then outstanding Convertible Preferred Stock automatically converted into an aggregate of 18,398,248 shares of common stock (see Note 8). 2021 Stock Incentive Plan In September 2021, the Company’s board of directors adopted, and in October 2021, the Company’s stockholders approved, the 2021 Stock Incentive Plan (the “2021 Plan”), which became effective on October 21, 2021, immediately prior to the effectiveness of the Company’s registration statement on Form S-1 filed with the SEC on October 1, 2021, as amended (the “Registration Statement”). The 2021 Plan provides for the grant of incentive stock options, nonstatutory stock options, stock appreciation rights, restricted stock awards, restricted stock units, and other stock-based awards. The number of shares of the Company’s common stock reserved for issuance under the 2021 Plan is the sum of (1) 2,654,828; plus (2) the number of shares (up to 3,967,038 shares) as is equal to the sum of (x) the number of shares of the Company’s common stock reserved for issuance under the 2020 Plan that remained available for grant under the 2020 Plan immediately prior to the effectiveness of the Registration Statement and (y) the number of shares of the Company’s common stock subject to outstanding awards whether granted under the 2020 Plan or outside of the 2020 Plan which awards expire, terminate or are otherwise surrendered, canceled, forfeited or repurchased by us at their original issuance price pursuant to a contractual repurchase right and that, prior to the effectiveness of the 2021 Plan, would have become available for issuance under the 2020 Plan; plus (3) an annual increase, to be added on the first day of each fiscal year, beginning with the fiscal year, commencing on January 1, 2022 and continuing until, and including, January 1, 2031, equal to the lesser of (i) 5% of the number of shares of our common stock outstanding on the first day of such fiscal year and (ii) the number of shares of common stock determined by the Company’s board of directors. 2021 Employee Stock Purchase Plan In September 2021, the Company’s board of directors adopted, and in October 2021, the Company’s stockholders approved the 2021 Employee Stock Purchase Plan (the “2021 ESPP”), which became effective on October 21, 2021, immediately prior to the effectiveness of the Registration Statement. The 2021 ESPP initially provides participating employees with the opportunity to purchase up to an aggregate of 292,031 shares of the Company’s common stock. The number of shares of common stock reserved for issuance under the 2021 ESPP will automatically increase on each January 1, beginning on January 1, 2022 and ending on January 1, 2031, by the lesser of (i) 584,062 shares of common stock, (ii) 1% of the number of shares of the Company’s common stock outstanding on such date, and (iii) a number of shares of common stock as determined by the Company’s board of directors.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Sep. 30, 2021
Summary of Significant Accounting Policies
Basis of Presentation	Basis of Presentation These condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”) and pursuant to the rules and regulations of the United States Securities and Exchange Commission, (the “SEC”). Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASUs”) of the Financial Accounting Standards Board (“FASB”). In April 2012, the Jumpstart Our Business Startups Act of 2012 (the “JOBS Act”) was enacted. Section 107(b) of the JOBS Act provides that an emerging growth company can take advantage of an extended transition period for complying with new or revised accounting standards. Thus, an emerging growth company can delay the adoption of certain accounting standards until those standards would otherwise apply to private companies. The Company has elected not to “opt out” of such extended transition period, which means that when a standard is issued or revised and it has different application dates for public or private companies, the Company can adopt the new or revised standard at the time private companies adopt the new or revised standard and may do so until such time that the Company either (1) irrevocably elects to “opt out” of such extended transition period or (2) no longer qualifies as an emerging growth company. The Company may take advantage of these exemptions up until the last day of the fiscal year following the fifth anniversary of its initial public offering or such earlier time that it is no longer an emerging growth company. The Company’s significant accounting policies are disclosed in the audited consolidated financial statements included in the Company’s final prospectus for its IPO, dated October 22, 2021, and filed with the SEC, pursuant to Rule 424(b)(4) under the Securities Act of 1933, as amended (the “Prospectus”). Since the date of such audited consolidated financial statements, there have been no changes to the Company’s significant accounting policies except as noted below.
Unaudited Interim Condensed Consolidated Financial Information	Unaudited Interim Condensed Consolidated Financial Information The accompanying condensed consolidated balance sheet as of September 30, 2021, the condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2021 and 2020, the statements of cash flows for the nine months ended September 30, 2021 and 2020 and the condensed consolidated statements of preferred units and convertible preferred stock and members’ and stockholders’ deficit for the nine months ended September 30, 2021 and 2020 are unaudited. The financial data and other information contained in the notes thereto as of and for the three and nine months ended September 30, 2021 and 2020 are also unaudited. The condensed consolidated balance sheet data as of December 31, 2020 was derived from the Company’s audited consolidated financial statements included in the Prospectus. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited annual consolidated financial statements, and in the opinion of management, reflect all adjustments, which include only normal recurring adjustments necessary for the fair presentation of the Company’s financial position as of September 30, 2021, the results of its operations for the three and nine months ended September 30, 2021 and 2020 and cash flows for the nine months ended September 30, 2021 and 2020. These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements as of and for the year ended December 31, 2020, and the notes thereto, included in the Prospectus. The results for the three and nine months ended September 30, 2021 are not necessarily indicative of results to be expected for the year ended December 31, 2021, or any other interim periods, or any future year or period.
Use of Estimates	Use of Estimates The preparation of financial statements in accordance with GAAP requires management to make estimates and judgments that may affect the reported amounts of assets and liabilities and related disclosures of contingent assets and liabilities at the date of the financial statements and the related reporting of expenses during the reporting period. Management considers many factors in selecting appropriate financial accounting policies and controls, and in developing the estimates and assumptions that are used in the preparation of these condensed consolidated financial statements. Factors that may affect estimates, include expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes and management must select an amount that falls within that range of reasonable estimates. Significant estimates of accounting reflected in these condensed consolidated financial statements include, but are not limited to, estimates related to accrued expenses, contingent liabilities associated with the consummation of specified transactions, including an initial public offering, the valuation of equity-based compensation, including incentive units, stock options and restricted common stock, and income taxes. Actual results could differ from those estimates.
Cash Equivalents and Restricted Cash	Cash Equivalents and Restricted Cash The Company considers all short-term, highly liquid investments with original maturities of 90 days or less at acquisition date to be cash equivalents. Cash equivalents, which consist of money market accounts, are stated at fair value. Restricted cash primarily represents a letter of credit issued to the landlord of the Company’s facility lease and is reflected in non-current assets on the accompanying condensed consolidated balance sheets. Cash, cash equivalents and restricted cash consists of the following (in thousands): September 30, December 31, 2021 2020 Cash and cash equivalents $ 99,767 $ 19,238 Restricted cash 1,553 1,551 Total cash, cash equivalents and restricted cash as shown on the condensed consolidated statement of cash flows $ 101,320 $ 20,789
Deferred Offering Costs	Deferred Offering Costs The Company capitalizes certain legal, professional, accounting and other third-party fees that are directly associated with in-process equity financings as deferred offering costs until the related financings are consummated. After consummation of the equity financing, such costs are reclassified as a reduction to additional paid-in capital generated as a result of the related financing. Should an in-process equity financing be abandoned, the deferred offering costs will be expensed immediately and accounted for as operating expenses in the condensed consolidated statements of operations and comprehensive loss. Deferred offering costs are presented as a component of other current assets on the condensed consolidated balance sheets. As of September 30, 2021, the Company capitalized $3.4 million of deferred offering costs related to its IPO. There were no deferred offering costs as of December 31, 2020.
Comprehensive Loss	Comprehensive Loss Comprehensive loss is the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. Comprehensive loss includes net loss and the change in accumulated other comprehensive loss for the period. The Company did not have any items of comprehensive loss other than its net loss for the three and nine months ended September 30, 2021 and 2020.
Equity-Based Compensation	Equity-Based Compensation The Company utilizes significant estimates and assumptions in determining the fair value of its equity and equity-based awards. Beginning in the nine months ended September 30, 2021, the Company determined the fair value of shares of its common stock underlying stock-based awards granted using a hybrid approach. The hybrid approach is a scenario-based analysis and where one or more of the scenarios allocate the equity value utilizing the option-pricing method (“OPM”). When using the hybrid approach, the Company estimates the probability-weighted value across multiple scenarios but used the OPM to estimate the allocation of value within at least one of the scenarios. In addition to a scenario using the OPM, the hybrid method also considers an initial public offering scenario in which the shares of convertible preferred stock are assumed to convert to common stock. The future value of the common stock in the initial public offering scenario was discounted back to the valuation date at an appropriate risk adjusted discount rate. In the hybrid method, the present value indicated for each scenario was probability weighted to arrive at an indication of value for the Company’s common stock.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements The Company did not adopt any new accounting standards during the nine-month period ended September 30, 2021. The Company continues to evaluate accounting standards that were recently issued but not yet adopted as of September 30, 2021.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	9 Months Ended
Summary of Significant Accounting Policies (Tables)	Sep. 30, 2021
Summary of Significant Accounting Policies
Schedule of cash, cash equivalents and restricted cash	Cash, cash equivalents and restricted cash consists of the following (in thousands): September 30, December 31, 2021 2020 Cash and cash equivalents $ 99,767 $ 19,238 Restricted cash 1,553 1,551 Total cash, cash equivalents and restricted cash as shown on the condensed consolidated statement of cash flows $ 101,320 $ 20,789

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
Fair Value Measurements (Tables)	Sep. 30, 2021
Fair Value Measurements
Schedule of financial liabilities at fair value on a recurring basis	The Company measures the following financial liabilities at fair value on a recurring basis. The fair value of these liabilities was determined as follows (in thousands): Quoted Prices in Active Significant Markets for Other Significant Identical Observable Unobservable September 30, Assets Inputs Inputs 2021 Level 1 Level 2 Level 3 Financial liabilities: Debt derivative liability $ 750 $ — $ — $ 750 Other derivative liability 500 — — 500 Warrant to purchase Series A convertible preferred stock 25 — — 25 Total financial liabilities $ 1,275 $ — $ — $ 1,275 Quoted Prices in Active Significant Markets for Other Significant Identical Observable Unobservable December 31, Assets Inputs Inputs 2020 Level 1 Level 2 Level 3 Financial liabilities: Debt derivative liability $ 396 $ — $ — $ 396 Other derivative liability 407 — — 407 Warrant to purchase Series A convertible preferred stock 22 — — 22 Total financial liabilities $ 825 $ — $ — $ 825
Schedule of change fair value of the liabilities, measured with Level 3	The following table summarizes the changes in the fair market value of the Company’s warrant liability, debt derivative liability and other derivative liability, which are classified within the Level 3 fair value hierarchy (in thousands): Total Debt Other level 3 Warrant derivative derivative financial liability liability liability liabilities Balance at December 31, 2020 $ 22 $ 396 $ 407 $ 825 Change in fair value of liability 3 354 93 450 Balance at September 30, 2021 $ 25 $ 750 $ 500 $ 1,275

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	9 Months Ended
Property and Equipment, Net (Tables)	Sep. 30, 2021
Property and Equipment, Net
Summary of property and equipment, net	Property and equipment, net consists of the following (in thousands): September 30, December 31, 2021 2020 Laboratory equipment $ 3,490 $ 2,925 Computers and software 228 228 Furniture and fixtures 636 482 Leasehold improvements 5,092 5,092 Construction in process 15 — Total property and equipment $ 9,461 $ 8,727 Less accumulated depreciation (2,353) (1,360) Property and equipment, net $ 7,108 $ 7,367

Accrued Expenses (Tables)

Accrued Expenses (Tables)	9 Months Ended
Accrued Expenses (Tables)	Sep. 30, 2021
Accrued Expenses
Summary of accrued expenses	Accrued expenses consist of the following (in thousands): September 30, December 31, 2021 2020 External research and development $ 3,238 $ 11,060 Personnel related 3,100 2,013 Professional services 1,569 481 Other 287 178 Total accrued expenses $ 8,194 $ 13,732

Loan and Security Agreement (Ta

Loan and Security Agreement (Tables)	9 Months Ended
Loan and Security Agreement (Tables)	Sep. 30, 2021
Loan and Security Agreement
Schedule of minimum aggregate future loan payments	The Company has the following minimum aggregate future loan payments under the Loan Agreement at September 30, 2021 (in thousands): Minimum Loan Payments 2021 $ — 2022 — 2023 6,667 2024 3,333 Total future principal payments 10,000 Less: unamortized discount (420) Total notes payable $ 9,580

Convertible Preferred Stock a_2

Convertible Preferred Stock and Common Stock (Tables)	9 Months Ended
Convertible Preferred Stock and Common Stock (Tables)	Sep. 30, 2021
Convertible Preferred Stock and Common Stock
Schedule of convertible preferred stock	The Company’s convertible preferred stock (collectively, the “Convertible Preferred Stock”) consisted of the following (in thousands, except share amounts): As of September 30, 2021 Common Preferred Shares Preferred Shares Issuable Shares Issued and Carrying Liquidation Upon Authorized Outstanding Value Preference Conversion Series A convertible preferred stock 7,525,000 7,500,000 $ 7,309 $ 7,500 789,473 Series A‑1 convertible preferred stock 19,565,216 19,565,216 20,740 22,500 2,059,496 Series B convertible preferred stock 79,446,624 79,446,624 100,153 100,500 8,362,793 Series C convertible preferred stock 68,271,641 68,271,641 94,686 95,000 7,186,486 174,808,481 174,783,481 $ 222,888 $ 225,500 18,398,248 As of December 31, 2020 Preferred Shares Common Shares Preferred Shares Issued and Carrying Liquidation Issuable Upon Authorized Outstanding Value Preference Conversion Series A convertible preferred stock 7,525,000 7,500,000 $ 7,309 $ 7,500 789,473 Series A‑1 convertible preferred stock 19,565,216 19,565,216 20,740 22,500 2,059,496 Series A‑2(A) convertible preferred stock 7,500,000 — — — — Series A‑2(A‑1) convertible preferred stock 19,565,216 — — — — Series B convertible preferred stock 79,446,624 39,723,312 49,953 50,250 4,181,390 133,602,056 66,788,528 $ 78,002 $ 80,250 7,030,359
Schedule of Shares Reserved for Future Issuance	September 30, December 31, 2021 2020 Shares of common stock reserved for conversion of convertible preferred stock outstanding 18,398,248 7,030,359 Shares of common stock reserved for conversion of convertible preferred shares issuable upon exercise of a warrant 2,631 2,631 Shares of common stock reserved for exercise of outstanding stock options under the 2020 Stock Incentive Plan 3,391,136 810,358 Shares of common stock reserved for future awards under the 2020 Stock Incentive Plan 429,109 151,769 Total shares reserved for future issuance 22,221,124 7,995,117

Equity-Based Compensation (Tabl

Equity-Based Compensation (Tables)	9 Months Ended
Equity-Based Compensation (Tables)	Sep. 30, 2021
Equity-Based Compensation
Schedule of company's restricted stock activity	Number Weighted of Shares Average of Restricted Grant Date Stock Fair Value Unvested as of December 31, 2020 283,969 $ 5.51 Vested (80,928) 5.51 Canceled/Forfeited (67,230) 5.51 Unvested as of September 30, 2021 135,811 5.51
Summary of stock option activity	Weighted Average Remaining Aggregate Weighted Contractual Intrinsic Number of Average Term Value Stock Options Exercise Price (In years) (In thousands) Outstanding as of December 31, 2020 810,358 $ 5.51 9.52 $ — Granted 2,993,919 7.32 Exercised (8,092) 5.55 Cancelled/forfeited (405,049) 6.17 Outstanding as of September 30, 2021 3,391,136 7.03 9.14 $ 15,795 Exercisable as of September 30, 2021 555,282 5.84 7.63 $ 3,243 Vested and expected to vest as of September 30, 2021 3,391,136 7.03 9.14 $ 15,795
Schedule of assumptions used in determining the fair value of options granted to employees	Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Risk-free interest rate 0.92 – 0.93 % 0.16 – 0.36 % 0.63 – 1.15 % 0.16 – 0.36 % Expected dividend yield 0 % 0 % 0 % 0 % Expected term (in years) 6.00 – 6.08 2.25 – 6.08 5.52 – 10.00 2.25 – 6.08 Expected volatility 80.60 – 80.76 % 78.84 –96.73 % 80.60 – 85.26 % 78.84 –96.73 %
Schedule of recorded compensation expense related to incentive units, stock options, and restricted common stock	During the three and nine months ended September 30, 2021 and 2020, the Company recorded compensation expense related to incentive units, stock options, and restricted common stock for employees and non-employees, which was allocated as follows in the condensed consolidated statements of operations and comprehensive loss (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Research and development expense $ 378 $ 183 $ 864 $ 240 General and administrative expense 713 500 2,023 690 Total equity-based compensation expense $ 1,091 $ 683 $ 2,887 $ 930

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	9 Months Ended
Net Loss Per Share (Tables)	Sep. 30, 2021
Net Loss Per Share
Schedule of antidilutive securities excluded from computation of diluted net loss per share	Nine Months Ended September 30, 2021 2020 Convertible preferred stock 18,398,248 7,030,359 Unvested restricted common stock 135,811 331,607 Outstanding stock options 3,391,136 854,978 Warrants 2,631 2,631 Total common stock equivalents 21,927,826 8,219,575

Description of Business, Orga_2

Description of Business, Organization and Liquidity (Details) - USD ($) $ / shares in Units, $ in Thousands	Nov. 01, 2021	Nov. 01, 2021	Oct. 26, 2021	Oct. 31, 2021	Sep. 30, 2021	Dec. 31, 2020
Sale of stock
Cash and cash equivalents					$ 99,767	$ 19,238
Substantial doubt about going concern within one year					false
IPO \| Subsequent events
Sale of stock
Gross proceeds received from IPO	$ 129,900
Net proceeds received from IPO	$ 116,300
Number of common shares issued upon conversion of preferred stock				18,398,248
IPO, Excluding Over-Allotment Option \| Subsequent events
Sale of stock
Number of shares issued and sold			7,353,000
Offering price (in dollar per share)			$ 16
Over-Allotment Option \| Subsequent events
Sale of stock
Number of shares issued and sold		766,106
Offering price (in dollar per share)	$ 16	$ 16

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Summary of Significant Accounting Policies
Cash and cash equivalents	$ 99,767	$ 19,238
Restricted cash	1,553	1,551
Total cash, cash equivalents and restricted cash as shown on the condensed consolidated statement of cash flows	$ 101,320	$ 20,789	$ 33,477	$ 49,039

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Deferred Offering Costs (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Summary of Significant Accounting Policies
Deferred offering costs	$ 3,400	$ 0

Fair Value Measurements - Finan

Fair Value Measurements - Financial liabilities at fair value on a recurring basis (Details) - Recurring basis - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Financial liabilities:
Total financial liabilities	$ 1,275	$ 825
Debt derivative liability
Financial liabilities:
Total financial liabilities	750	396
Other derivative liability
Financial liabilities:
Total financial liabilities	500	407
Warrant to purchase Series A convertible preferred stock
Financial liabilities:
Total financial liabilities	25	22
Level 3
Financial liabilities:
Total financial liabilities	1,275	825
Level 3 \| Debt derivative liability
Financial liabilities:
Total financial liabilities	750	396
Level 3 \| Other derivative liability
Financial liabilities:
Total financial liabilities	500	407
Level 3 \| Warrant to purchase Series A convertible preferred stock
Financial liabilities:
Total financial liabilities	$ 25	$ 22

Fair Value Measurements - Trans

Fair Value Measurements - Transfers between levels (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Fair Value Measurements
Transfer of Level 1 to level 2	$ 0	$ 0
Transfer of Level 2 to level 1	0	0
Transfer into level 3	0	0
Transfer out level 3	$ 0	$ 0

Fair Value Measurements - Chang

Fair Value Measurements - Change in fair market value of liability which classified as level 3 (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 16, 2021	Nov. 30, 2019
Changes in the fair market value of liabilities
Balance at December 31, 2020	$ 825
Change in fair value of liability	450
Balance at September 30, 2021	1,275
Loan Agreement and Amended Loan Agreement
Changes in the fair market value of liabilities
Fee payable upon occurrence of liquidation events, including initial public offering	800	$ 500	$ 500
Warrant to purchase Series A convertible preferred stock
Changes in the fair market value of liabilities
Balance at December 31, 2020	22
Change in fair value of liability	3
Balance at September 30, 2021	25
Debt derivative liability
Changes in the fair market value of liabilities
Balance at December 31, 2020	396
Change in fair value of liability	354
Balance at September 30, 2021	750
Other derivative liability
Changes in the fair market value of liabilities
Balance at December 31, 2020	407
Change in fair value of liability	93
Balance at September 30, 2021	$ 500

Property and Equipment, Net (De

Property and Equipment, Net (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Property and Equipment, Net
Property and equipment, gross	$ 9,461		$ 8,727
Less accumulated depreciation	(2,353)		(1,360)
Property and equipment, net	7,108		7,367
Depreciation	1,000	$ 700
Laboratory equipment
Property and Equipment, Net
Property and equipment, gross	3,490		2,925
Computers and software
Property and Equipment, Net
Property and equipment, gross	228		228
Furniture & fixtures
Property and Equipment, Net
Property and equipment, gross	636		482
Leasehold improvements
Property and Equipment, Net
Property and equipment, gross	5,092		$ 5,092
Construction in process
Property and Equipment, Net
Property and equipment, gross	$ 15

Accrued Expenses (Details)

Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Accrued Expenses
External research and development	$ 3,238	$ 11,060
Personnel related	3,100	2,013
Professional services	1,569	481
Other	287	178
Total accrued expenses	$ 8,194	$ 13,732

Loan and Security Agreement - D

Loan and Security Agreement - Description (Details) - Loan Agreement and Amended Loan Agreement - USD ($) $ in Millions	Sep. 17, 2021	Oct. 31, 2021	Nov. 30, 2019	Sep. 30, 2021	Sep. 16, 2021
Loan and security agreement
Borrowed amount	$ 10		$ 10
Additional borrowing capacity	$ 10
Fee payable upon occurrence of liquidation events, including initial public offering			$ 0.5	$ 0.8	$ 0.5
Fee paid upon closing of IPO		$ 0.8
Fee payable (as percent)	1.00%
Additional interest rate upon event of default (as a percent)	5.00%
Minimum
Loan and security agreement
Stated interest rate	4.75%		5.00%
Fee payable upon occurrence of liquidation events, including initial public offering	$ 0.8
Maximum
Loan and security agreement
Fee payable upon occurrence of liquidation events, including initial public offering	$ 1
Debt derivative liability
Loan and security agreement
Derivative liability			$ 0.4
Prime rate
Loan and security agreement
Basis spread (as percent)	0.25%		0.25%

Loan and Security Agreement - M

Loan and Security Agreement - Maturities (Details) - Loan Agreement and Amended Loan Agreement - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Minimum aggregate future loan payments
2023	$ 6,667
2024	3,333
Total future principal payments	10,000
Less: unamortized discount	(420)
Total notes payable	9,580
Interest expense	$ 500	$ 400

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Millions	Sep. 30, 2021USD ($)
Commitments and Contingencies
Leases, letter of credit for the benefit of its landlord	$ 1.6

Convertible Preferred Stock a_3

Convertible Preferred Stock and Common Stock - Convertible Preferred Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	Feb. 23, 2021	Jan. 20, 2021	Mar. 31, 2021	Sep. 30, 2021	Feb. 22, 2021	Dec. 31, 2020
Convertible Preferred Stock
Convertible preferred stock, Authorized				174,808,481	174,808,481	133,602,056
Series A Convertible Preferred Stock
Convertible Preferred Stock
Convertible preferred stock, Authorized				7,525,000	7,525,000	7,525,000
Series A-1 Convertible Preferred Stock
Convertible Preferred Stock
Convertible preferred stock, Authorized				19,565,216	19,565,216	19,565,216
Series A-2 (A) Convertible Preferred Stock
Convertible Preferred Stock
Convertible preferred stock, Authorized						7,500,000
Series A-2 (A-1) Convertible Preferred Stock
Convertible Preferred Stock
Convertible preferred stock, Authorized						19,565,216
Series B Convertible Preferred Stock
Convertible Preferred Stock
Convertible preferred stock, Authorized				79,446,624	79,446,624	79,446,624
Convertible preferred stock, share issued		39,723,312	39,723,312
Share price, Convertible preferred stock (in dollars per share)		$ 1.265
Cash proceeds		$ 50,200		$ 50,200
Series C Convertible Preferred Stock
Convertible Preferred Stock
Convertible preferred stock, Authorized				68,271,641	68,271,641
Convertible preferred stock, share issued	68,271,641		68,271,641
Share price, Convertible preferred stock (in dollars per share)	$ 1.3915
Cash proceeds	$ 94,700			$ 94,686

Convertible Preferred Stock a_4

Convertible Preferred Stock and Common Stock - Components (Details) - USD ($) $ in Thousands	1 Months Ended
	Oct. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Feb. 22, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020
Convertible Preferred Stock
Preferred Shares Authorized		174,808,481			174,808,481	133,602,056
Preferred Shares Issued		174,783,481				66,788,528
Preferred Shares Outstanding		174,783,481				66,788,528
Carrying Value		$ 222,888				$ 78,002
Liquidation Preference		$ 225,500				$ 80,250
Common Shares Issuable Upon Conversion		18,398,248				7,030,359
Subsequent events \| IPO
Convertible Preferred Stock
Number of common shares issued upon conversion of preferred stock	18,398,248
Series A Convertible Preferred Stock
Convertible Preferred Stock
Preferred Shares Authorized		7,525,000			7,525,000	7,525,000
Preferred Shares Issued		7,500,000				7,500,000
Preferred Shares Outstanding		7,500,000	7,500,000	7,500,000		7,500,000	7,500,000	7,500,000
Carrying Value		$ 7,309	$ 7,309	$ 7,309		$ 7,309	$ 7,309	$ 7,309
Liquidation Preference		$ 7,500				$ 7,500
Common Shares Issuable Upon Conversion		789,473				789,473
Series A-1 Convertible Preferred Stock
Convertible Preferred Stock
Preferred Shares Authorized		19,565,216			19,565,216	19,565,216
Preferred Shares Issued		19,565,216				19,565,216
Preferred Shares Outstanding		19,565,216	19,565,216	19,565,216		19,565,216	19,565,216	19,565,216
Carrying Value		$ 20,740	$ 20,740	$ 20,740		$ 20,740	$ 20,740	$ 20,740
Liquidation Preference		$ 22,500				$ 22,500
Common Shares Issuable Upon Conversion		2,059,496				2,059,496
Series A-2 (A) Convertible Preferred Stock
Convertible Preferred Stock
Preferred Shares Authorized						7,500,000
Series A-2 (A-1) Convertible Preferred Stock
Convertible Preferred Stock
Preferred Shares Authorized						19,565,216
Series B Convertible Preferred Stock
Convertible Preferred Stock
Preferred Shares Authorized		79,446,624			79,446,624	79,446,624
Preferred Shares Issued		79,446,624				39,723,312
Preferred Shares Outstanding		79,446,624	79,446,624	79,446,624		39,723,312	39,723,312	39,723,312
Carrying Value		$ 100,153	$ 100,153	$ 100,153		$ 49,953	$ 49,953	$ 49,953
Liquidation Preference		$ 100,500				$ 50,250
Common Shares Issuable Upon Conversion		8,362,793				4,181,390
Series C Convertible Preferred Stock
Convertible Preferred Stock
Preferred Shares Authorized		68,271,641			68,271,641
Preferred Shares Issued		68,271,641
Preferred Shares Outstanding		68,271,641	68,271,641	68,271,641
Carrying Value		$ 94,686	$ 94,686	$ 94,686
Liquidation Preference		$ 95,000
Common Shares Issuable Upon Conversion		7,186,486

Convertible Preferred Stock a_5

Convertible Preferred Stock and Common Stock - Shares Reserved for Future Issuance (Details) - $ / shares	Sep. 30, 2021	Dec. 31, 2020
Convertible Preferred Stock and Common Stock
Common stock, shares authorized	220,400,000	126,000,000
Common stock, par value	$ 0.0001	$ 0.0001
Shares of common stock reserved for conversion of convertible preferred stock outstanding	18,398,248	7,030,359
Shares of common stock reserved for conversion of convertible preferred shares issuable upon exercise of a warrant	2,631	2,631
Shares of common stock reserved for exercise of outstanding stock options under the 2020 Stock Incentive Plan	3,391,136	810,358
Shares of common stock reserved for future awards under the 2020 Stock Incentive Plan	429,109	151,769
Total shares reserved for future issuance	22,221,124	7,995,117

Equity-Based Compensation - Equ

Equity-Based Compensation - Equity incentive plans (Details) - Equity Incentive Plans - shares	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Equity-Based Compensation
Shares authorized under plan	3,773,235	991,021
Additional common stock issuable under the plan	364,120

Equity-Based Compensation - Res

Equity-Based Compensation - Restricted Stock (Details) - Restricted Stock - USD ($) $ / shares in Units, $ in Millions	6 Months Ended	9 Months Ended
	Jun. 30, 2020	Sep. 30, 2021
Number of Shares of Restricted Stock
Unvested at beginning of period (in shares)		283,969
Vested (in shares)		(80,928)
Canceled/Forfeited (in shares)		(67,230)
Unvested at end of period (in shares)		135,811
Weighted Average Grant Date Fair Value
Unvested at the beginning of the period (in dollars per share)		$ 5.51
Vested (in dollars per share)		5.51
Cancelled/forfeited (in dollars per share)		5.51
Unvested at end of period (in dollars per share)		$ 5.51
Restricted stock awards granted	552,546
Aggregate fair value of restricted stock awards		$ 0.7
Total unrecognized compensation cost of unvested restricted stock awards		$ 0.8
Weighted-average period for unrecognized compensation cost to be recognized		1 year 11 months 23 days

Equity-Based Compensation - Sto

Equity-Based Compensation - Stock option activity (Details) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021USD ($)$ / sharesshares	Dec. 31, 2020$ / sharesshares
Options Outstanding
Outstanding at beginning of period (in shares)	810,358
Granted (in shares)	2,993,919
Exercised (in shares)	(8,092)
Cancelled/forfeited (in shares)	(405,049)
Outstanding at end of period (in shares)	3,391,136	810,358
Exercisable at end of period (in shares)	555,282
Vested and expected to vest at end of period (in shares)	3,391,136
Weighted Average Exercise Price
Outstanding (in dollars per share) \| $ / shares	$ 7.03	$ 5.51
Granted (in dollars per share) \| $ / shares	7.32
Exercised (in dollars per share) \| $ / shares	5.55
Cancelled/forfeited (in dollars per share) \| $ / shares	6.17
Exercisable at end of period (in dollars per share) \| $ / shares	5.84
Vested and expected to vest at end of period (in dollars per share) \| $ / shares	$ 7.03
Weighted Average Remaining Contractual Term (In years)
Outstanding (in years)	9 years 1 month 20 days	9 years 6 months 7 days
Exercisable at the end of the year (in years)	7 years 7 months 17 days
Vested and expected to vest at end of period (in years)	9 years 1 month 20 days
Aggregate Intrinsic Value
Outstanding (in dollars) \| $	$ 15,795
Exercisable (in dollars) \| $	3,243
Vested and expected to vest (in dollars) \| $	$ 15,795

Equity-Based Compensation - Fai

Equity-Based Compensation - Fair value of options using black-scholes option pricing model (Details) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)employee$ / sharesshares	Sep. 30, 2020USD ($)$ / shares
Equity-Based Compensation
Fair value of options granted (in dollars per share) \| $ / shares			$ 5.16	$ 3.60
Stock options granted during the period (in shares) \| shares			2,993,919
Equity-based compensation expense	$ 1,091	$ 683	$ 2,887	$ 930
Former employees providing consulting services
Equity-Based Compensation
Equity-based compensation expense			$ 200
Number of former employees \| employee			2
Additional period granted for exercise of vested options			90 days
Stock options
Equity-Based Compensation
Risk-free interest rate, minimum (as a percent)	0.92%	0.16%	0.63%	0.16%
Risk-free interest rate, maximum (as a percent)	0.93%	0.36%	1.15%	0.36%
Expected dividend yield (as a percent)	0.00%	0.00%	0.00%	0.00%
Expected volatility, minimum (as percentage)	80.60%	78.84%	80.60%	78.84%
Expected volatility, maximum (as percentage)	80.76%	96.73%	85.26%	96.73%
Stock options \| Minimum
Equity-Based Compensation
Expected term (in years)	6 years	2 years 3 months	5 years 6 months 7 days	2 years 3 months
Stock options \| Maximum
Equity-Based Compensation
Expected term (in years)	6 years 29 days	6 years 29 days	10 years	6 years 29 days
Stock options, excluding performance-based awards
Equity-Based Compensation
Total unrecognized compensation cost	$ 13,100		$ 13,100
Weighted-average period for unrecognized compensation cost to be recognized			3 years 2 months 19 days
Stock options, vesting based on performance
Equity-Based Compensation
Equity-based compensation expense			$ 0
Total unrecognized compensation cost	$ 500		$ 500

Equity-Based Compensation - E_2

Equity-Based Compensation - Equity-based compensation expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Equity-Based Compensation
Total compensation expense	$ 1,091	$ 683	$ 2,887	$ 930
Research and development expense
Equity-Based Compensation
Total compensation expense	378	183	864	240
General and administrative expense
Equity-Based Compensation
Total compensation expense	$ 713	$ 500	$ 2,023	$ 690

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	9 Months Ended
Income Taxes (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Sep. 30, 2020
Income Taxes
Provision or benefit for income taxes	$ 0	$ 0

Net Loss Per Share (Details)

Net Loss Per Share (Details) - shares	9 Months Ended
Net Loss Per Share (Details) - shares	Sep. 30, 2021	Sep. 30, 2020
Net Loss Per Share
Total common stock equivalents	21,927,826	8,219,575
Convertible preferred stock
Net Loss Per Share
Total common stock equivalents	18,398,248	7,030,359
Restricted Stock
Net Loss Per Share
Total common stock equivalents	135,811	331,607
Stock options
Net Loss Per Share
Total common stock equivalents	3,391,136	854,978
Warrants
Net Loss Per Share
Total common stock equivalents	2,631	2,631

Subsequent Events (Details)

Subsequent Events (Details) $ / shares in Units, $ in Thousands	Nov. 01, 2021USD ($)$ / shares	Nov. 01, 2021$ / sharesshares	Oct. 26, 2021$ / sharesshares	Oct. 15, 2021	Oct. 31, 2021shares	Sep. 30, 2021shares	Dec. 31, 2020shares
Subsequent Events
Common stock reserved for issuance (in shares)						22,221,124	7,995,117
Subsequent events
Subsequent Events
Reverse stock split				0.1053
Subsequent events \| 2021 Stock Incentive Plan
Subsequent Events
Common stock reserved for issuance (in shares)					2,654,828
Additional common stock reserved for issuance (in shares)					3,967,038
Annual increase in number of shares reserved for issuance (as a percent)					5.00%
Subsequent events \| Employee Stock Purchase Plan
Subsequent Events
Shares authorized under plan					292,031
Subsequent events \| IPO
Subsequent Events
Gross proceeds received from IPO \| $	$ 129,900
Net proceeds received from IPO \| $	$ 116,300
Number of common shares issued upon conversion of preferred stock					18,398,248
Subsequent events \| IPO, Excluding Over-Allotment Option
Subsequent Events
Number of shares issued and sold			7,353,000
Offering price (in dollar per share) \| $ / shares			$ 16
Subsequent events \| Over-Allotment Option
Subsequent Events
Number of shares issued and sold		766,106
Offering price (in dollar per share) \| $ / shares	$ 16	$ 16
Subsequent events \| Maximum \| Employee Stock Purchase Plan
Subsequent Events
Annual increase in number of shares reserved and available for issuance (in shares)					584,062
Annual increase in number of shares reserved for issuance (as a percent)					1.00%