Xilio Therapeutics (XLO) 10-Q9 Nov 222022 Q3 Quarterly reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2022	Nov. 04, 2022
Document and Entity Information [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2022
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	857
Local Phone Number	524-2466
Title of 12(b) Security	Common stock, par value $0.0001 per share
Trading Symbol	XLO
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		27,471,607
Entity Central Index Key	0001840233
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q3
Amendment Flag	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Current assets
Cash and cash equivalents	$ 139,143	$ 198,053
Prepaid expenses and other current assets	3,171	4,464
Total current assets	142,314	202,517
Restricted cash	1,557	1,553
Property and equipment, net	7,553	7,620
Operating lease right-of-use asset	5,689	5,977
Other non-current assets	301	393
Total assets	157,414	218,060
Current liabilities
Accounts payable	1,810	3,144
Accrued expenses	9,062	8,751
Operating lease liability, current portion	888	801
Notes payable, current portion	5,000
Other current liabilities	82	82
Total current liabilities	16,842	12,778
Notes payable, net of current portion	4,781	9,628
Operating lease liability, net of current portion	9,429	10,107
Other liabilities, long-term	64	118
Total liabilities	31,116	32,631
Commitments and contingencies (Note 7)
Stockholders' equity
Preferred stock, $0.0001 par value; 5,000,000 shares authorized, no shares issued or outstanding at September 30, 2022 and December 31, 2021
Common stock, $0.0001 par value; 200,000,000 shares authorized at September 30, 2022 and December 31, 2021; 27,471,607 shares issued and 27,407,149 shares outstanding at September 30, 2022; 27,468,950 shares issued and 27,358,375 shares outstanding at December 31, 2021	3	3
Additional paid-in capital	352,937	346,312
Accumulated deficit	(226,642)	(160,886)
Total stockholders' equity (deficit)	126,298	185,429
Total liabilities and stockholders' equity	$ 157,414	$ 218,060

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 2022	Dec. 31, 2021
CONSOLIDATED BALANCE SHEETS
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	27,471,607	27,468,950
Common stock, shares outstanding	27,407,149	27,358,375

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Operating expenses
Research and development	$ 13,038	$ 10,470	$ 44,204	$ 39,836
General and administrative	7,168	5,491	21,778	15,652
Total operating expenses	20,206	15,961	65,982	55,488
Loss from operations	(20,206)	(15,961)	(65,982)	(55,488)
Other income (expense), net
Other income (expense), net	416	(290)	226	(611)
Total other income (expense), net	416	(290)	226	(611)
Net loss	(19,790)	(16,251)	(65,756)	(56,099)
Comprehensive loss	$ (19,790)	$ (16,251)	$ (65,756)	$ (56,099)
Net loss per share, basic (in dollars per share)	$ (0.72)	$ (21.27)	$ (2.40)	$ (76.18)
Net loss per share, diluted (in dollars per share)	$ (0.72)	$ (21.27)	$ (2.40)	$ (76.18)
Weighted average common shares outstanding, basic (in shares)	27,399,906	763,869	27,384,085	736,416
Weighted average common shares outstanding, diluted (in shares)	27,399,906	763,869	27,384,085	736,416

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021
Series A Convertible Preferred Stock
Temporary Equity
Beginning balance	$ 7,309	$ 7,309	$ 7,309
Beginning balance (in shares)	7,500,000	7,500,000	7,500,000
Issuance of preferred stock or units, net of issuance costs	$ 0	$ 0	$ 0
Issuance of preferred stock or units (in shares)	0	0	0
Ending balance	$ 7,309	$ 7,309	$ 7,309
Ending balance (in shares)	7,500,000	7,500,000	7,500,000
Series A-1 Convertible Preferred Stock
Temporary Equity
Beginning balance	$ 20,740	$ 20,740	$ 20,740
Beginning balance (in shares)	19,565,216	19,565,216	19,565,216
Issuance of preferred stock or units, net of issuance costs	$ 0	$ 0	$ 0
Issuance of preferred stock or units (in shares)	0	0	0
Ending balance	$ 20,740	$ 20,740	$ 20,740
Ending balance (in shares)	19,565,216	19,565,216	19,565,216
Series B Convertible Preferred Stock
Temporary Equity
Beginning balance	$ 100,153	$ 100,153	$ 49,953
Beginning balance (in shares)	79,446,624	79,446,624	39,723,312
Issuance of preferred stock or units, net of issuance costs	$ 0	$ 0	$ 50,200
Issuance of preferred stock or units (in shares)	0	0	39,723,312
Ending balance	$ 100,153	$ 100,153	$ 100,153
Ending balance (in shares)	79,446,624	79,446,624	79,446,624
Series C Convertible Preferred Stock
Temporary Equity
Beginning balance	$ 94,686	$ 94,686
Beginning balance (in shares)	68,271,641	68,271,641
Issuance of preferred stock or units, net of issuance costs	$ 0	$ 0	$ 94,686
Issuance of preferred stock or units (in shares)	0	0	68,271,641
Ending balance	$ 94,686	$ 94,686	$ 94,686
Ending balance (in shares)	68,271,641	68,271,641	68,271,641

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK (Parenthetical) $ in Thousands	3 Months Ended
	Mar. 31, 2021 USD ($)
Series B Convertible Preferred Stock
Issuance costs	$ 50
Series C Convertible Preferred Stock
Issuance costs	$ 314

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Total
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		25		25
Exercise of stock options (in shares)	4,473
Equity-based compensation expense		794		794
Net loss			(16,667)	(16,667)
Ending balance at Mar. 31, 2021		2,618	(101,753)	(99,135)
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
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		2,618	(101,753)	(99,135)
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		5		5
Exercise of stock options (in shares)	1,034
Equity-based compensation expense		1,002		1,002
Net loss			(23,181)	(23,181)
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
Equity-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
Ending balance at Dec. 31, 2021	$ 3	346,312	(160,886)	185,429
Ending balance (in shares) at Dec. 31, 2021	27,358,375
Stockholders' Deficit
Vesting of restricted common stock (in shares)	15,441
Exercise of stock options		16		16
Exercise of stock options (in shares)	2,657
Equity-based compensation expense		2,029		2,029
Net loss			(21,353)	(21,353)
Ending balance at Mar. 31, 2022	$ 3	348,357	(182,239)	166,121
Ending balance (in shares) at Mar. 31, 2022	27,376,473
Beginning balance at Dec. 31, 2021	$ 3	346,312	(160,886)	$ 185,429
Beginning balance (in shares) at Dec. 31, 2021	27,358,375
Stockholders' Deficit
Exercise of stock options (in shares)				2,657
Net loss				$ (65,756)
Ending balance at Sep. 30, 2022	$ 3	352,937	(226,642)	126,298
Ending balance (in shares) at Sep. 30, 2022	27,407,149
Beginning balance at Mar. 31, 2022	$ 3	348,357	(182,239)	166,121
Beginning balance (in shares) at Mar. 31, 2022	27,376,473
Stockholders' Deficit
Vesting of restricted common stock (in shares)	15,361
Equity-based compensation expense		2,709		2,709
Net loss			(24,613)	(24,613)
Ending balance at Jun. 30, 2022	$ 3	351,066	(206,852)	144,217
Ending balance (in shares) at Jun. 30, 2022	27,391,834
Stockholders' Deficit
Vesting of restricted common stock (in shares)	15,315
Equity-based compensation expense		1,871		1,871
Net loss			(19,790)	(19,790)
Ending balance at Sep. 30, 2022	$ 3	$ 352,937	$ (226,642)	$ 126,298
Ending balance (in shares) at Sep. 30, 2022	27,407,149

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Cash flows from operating activities:
Net loss	$ (65,756)	$ (56,099)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,358	1,105
Non-cash interest expense	164	121
Equity-based compensation expense	6,609	2,887
Loss on disposal of property and equipment	1	19
Change in fair value of warrant and derivative liabilities		199
Changes in operating assets and liabilities:
Prepaid and other assets	1,283	(3,597)
Operating lease right-of-use asset	288	244
Accounts payable	(972)	(1,626)
Accrued expenses and other liabilities	116	(6,459)
Operating lease liability	(591)	(383)
Net cash used in operating activities	(57,500)	(63,589)
Cash flows from investing activities:
Purchases of property and equipment	(1,358)	(722)
Net cash used in investing activities	(1,358)	(722)
Cash flows from financing activities:
Repayments of debt principal		(1,000)
Proceeds from debt issuance, net of issuance costs		975
Payments of finance lease	(64)	(63)
Proceeds from issuance of convertible preferred stock, net of issuance costs		144,886
Proceeds from exercise of stock options	16	44
Net cash (used in) provided by financing activities	(48)	144,842
(Decrease) increase in cash, cash equivalents and restricted cash	(58,906)	80,531
Cash, cash equivalents and restricted cash, beginning of period	199,606	20,789
Cash, cash equivalents and restricted cash, end of period	140,700	101,320
Supplemental cash flow disclosure:
Cash paid for interest	380	371
Supplemental disclosure of non-cash activities:
Capital expenditures included in accounts payable or accrued expenses	$ 371	47
Deferred offering costs included in accounts payable or accrued expenses		879
Recognition of derivative liability in connection with long-term debt facility		$ 250

Description of Business, Initia

Description of Business, Initial Public Offering and Liquidity and Capital Resources	9 Months Ended
	Sep. 30, 2022
Description of Business, Initial Public Offering and Liquidity and Capital Resources
Description of Business, Initial Public Offering and Liquidity and Capital Resources	1. Description of Business, Initial Public Offering and Liquidity and Capital Resources Description of Business Xilio Therapeutics, Inc. (“Xilio” or the “Company”) is a clinical-stage biotechnology company focused on harnessing the immune system to achieve deep and durable clinical responses to improve the lives of patients with cancer. The Company was incorporated in Delaware in June 2020, and its headquarters are based in Waltham, Massachusetts. Initial Public Offering In the fourth quarter of 2021, the Company completed its initial public offering (“IPO”) of common stock, in which it issued and sold an aggregate of 8,119,106 shares of its common stock, including 766,106 shares pursuant to the partial exercise by the underwriters of their option to purchase additional shares, at a public offering price of $16.00 per share. The Company received $116.4 million in net proceeds, after deducting underwriting discounts and commissions and offering expenses payable by the Company. Liquidity and Capital Resources Since its 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 the successful research, development and manufacturing of product candidates, and, if approved, any products, obtaining regulatory approvals for product candidates, and, if approved, commercialization of any products, protection and enforcement of intellectual property and proprietary technology, development by third parties of potentially competitive products or product candidates, compliance with governmental regulations, and the ability to secure additional capital to fund operations. Programs currently under development will require significant additional research and development efforts, including preclinical and clinical testing and manufacturing process development and will need to obtain regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel and infrastructure and extensive compliance-reporting capabilities. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will realize revenue from product sales. As of September 30, 2022, the Company had cash and cash equivalents of $139.1 million. The Company believes that its existing cash and cash equivalents will be sufficient to enable the Company to fund its operating expenses and capital expenditure requirements into the second quarter of 2024, which is 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 and will need additional capital in the future to support its continuing operations and growth strategy as it continues to invest significantly in research and development of its product candidates, including preclinical and clinical testing and manufacturing process development. To date, the Company has primarily funded its operations with proceeds from the sale of convertible preferred units and convertible preferred stock, a debt financing and the IPO. 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 capital sooner 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, 2022
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 (“GAAP”) and pursuant to the rules and regulations of the United States Securities and Exchange Commission, (the “SEC”). Certain information and footnote disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. These condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and the notes thereto included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2021. 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. In connection with its IPO, the Company effected a 1-for-9.5 Principles of Consolidation The accompanying condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries: Xilio Development, Inc., a Delaware corporation and Xilio Securities Corporation, a Massachusetts corporation, created to buy, sell and hold securities. Effective as of September 30, 2022, the Company’s wholly owned subsidiaries, Xilio Therapeutics, LLC and Xilio Concerto, LLC, were merged with and into Xilio Development, Inc., with Xilio Development, Inc. as the surviving corporation. All intercompany accounts and transactions have been eliminated in consolidation. Significant Accounting Policies The significant accounting policies used in preparation of the unaudited condensed consolidated financial statements are described in Note 2, “ Summary of Significant Accounting Policies ” of the audited consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2021. There have been no material changes to the significant accounting policies previously disclosed in the Company’s Annual Report on Form 10-K for the year ended December 31, 2021. Unaudited Interim Condensed Consolidated Financial Information The accompanying condensed consolidated financial statements are unaudited. The financial data and other information contained in these notes are also unaudited. The condensed consolidated balance sheet data as of December 31, 2021 was derived from the Company’s audited consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2021. 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, 2022, the results of its operations for the three and nine months ended September 30, 2022 and 2021 and cash flows for the nine months ended September 30, 2022 and 2021. 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, 2021, and the notes thereto, included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2021. The results for the three and nine months ended September 30, 2022 are not necessarily indicative of results to be expected for the year ended December 31, 2022, 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, the valuation of equity-based compensation, including stock options and restricted common stock, the useful life of long-lived assets and income taxes. Actual results could differ from those estimates. 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: September 30, September 30, 2022 2021 Cash and cash equivalents $ 139,143 $ 99,767 Restricted cash 1,557 1,553 Total cash, cash equivalents and restricted cash as shown on the consolidated statement of cash flows $ 140,700 $ 101,320 Recently Adopted Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326)—Measurement of Credit Losses on Financial Instruments , as amended (“ASU 2016-13”). The provisions of ASU 2016-13 modify the impairment model to utilize an expected loss methodology in place of the previously used incurred loss methodology and require a consideration of a broader range of reasonable and supportable information to inform credit loss estimates. The Company adopted ASU 2016-13 as of January 1, 2022, and the adoption did not have a material effect on its condensed consolidated financial statements and related disclosures. In August 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470 - 20) and Derivatives and Hedging Contracts in Entity’s Own Equity (Subtopic 815 - 40) derivatives scope exception for contracts in an entity’s own equity. The Company adopted ASU 2020-06 as of January 1, 2022, and the adoption did not have a material effect on its condensed consolidated financial statements and related disclosures.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
Fair Value Measurements	Sep. 30, 2022
Fair Value Measurements
Fair Value Measurements	3. Fair Value Measurements The Company measures the following financial assets at fair value on a recurring basis. The fair value of these assets was determined as follows: Quoted Prices in Active Significant Markets for Other Significant Identical Observable Unobservable September 30, Assets Inputs Inputs 2022 Level 1 Level 2 Level 3 Financial assets: Cash equivalents—money market funds $ 936 $ 936 $ — $ — Total financial assets $ 936 $ 936 $ — $ — Quoted Prices in Active Significant Markets for Other Significant Identical Observable Unobservable December 31, Assets Inputs Inputs 2021 Level 1 Level 2 Level 3 Financial assets: Cash equivalents—money market funds $ 8,534 $ 8,534 $ — $ — Total financial assets $ 8,534 $ 8,534 $ — $ — During the nine months ended September 30, 2022 and 2021, there were no transfers between Level 1, Level 2, and Level 3.

Property and Equipment, Net

Property and Equipment, Net	9 Months Ended
Property and Equipment, Net	Sep. 30, 2022
Property and Equipment, Net
Property and Equipment, Net	4. Property and Equipment, Net Property and equipment, net consists of the following as of September 30, 2022 and December 31, 2021: September 30, December 31, 2022 2021 Laboratory equipment $ 5,433 $ 3,805 Computers and software 228 228 Furniture and fixtures 636 636 Leasehold improvements 5,124 5,124 Construction in process 95 539 Total property and equipment $ 11,516 $ 10,332 Less accumulated depreciation (3,963) (2,712) Property and equipment, net $ 7,553 $ 7,620 The Company incurred depreciation and amortization expense related to property and equipment of $1.3 million and $1.0 million for the nine months ended September 30, 2022 and 2021, respectively.

Accrued Expenses

Accrued Expenses	9 Months Ended
Accrued Expenses	Sep. 30, 2022
Accrued Expenses
Accrued Expenses	5. Accrued Expenses Accrued expenses consist of the following as of September 30, 2022 and December 31, 2021: September 30, December 31, 2022 2021 External research and development $ 4,306 $ 2,794 Personnel-related 3,728 5,145 Professional and consulting fees 764 491 Other 264 321 Total accrued expenses $ 9,062 $ 8,751

Loan and Security Agreement

Loan and Security Agreement	9 Months Ended
Loan and Security Agreement	Sep. 30, 2022
Loan and Security Agreement
Loan and Security Agreement	6. Loan and Security Agreement In November 2019, the Company entered into a loan and security agreement with Pacific Western Bank (“PacWest”), as amended (the “Loan Agreement”), pursuant to which the Company borrowed $10.0 million under a term loan and has the ability to request one or more additional term loans in an aggregate principal amount of $10.0 million prior to December 31, 2022. Interest on amounts outstanding under the Loan Agreement accrue at a variable annual rate equal to the greater of (i) the prime rate plus 0.25% or (ii) 4.75%. As of September 30, 2022 the interest rate on the term loan is 6.5%. 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 term loan matures on June 30, 2024. In addition, under the Loan Agreement, the Company paid a one-time success fee of $0.8 million to PacWest in October 2021 upon the closing of the IPO. 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, 2022, 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 as of September 30, 2022: Minimum Loan Payments 2022 $ — 2023 6,667 2024 3,333 Total future principal payments 10,000 Less: unamortized discount (219) Total notes payable $ 9,781 The Company recognized $0.5 million of interest expense related to the Loan Agreement during each of the nine months ended September 30, 2022 and 2021, respectively, which is reflected in other income (expense), net on the condensed consolidated statements of operations and comprehensive loss.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Sep. 30, 2022
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. In August 2019, the Company entered into a lease agreement with a landlord providing funding for tenant improvements and occupancy of approximately 27,830 square feet of office and laboratory space at 828 Winter Street, Waltham, Massachusetts. The initial term of the lease expires in March 2030, unless terminated earlier in accordance with the terms of the lease. The Company has an option to extend the lease for a period of five years at then-market rates. The Company is obligated to pay its portion of real estate taxes and costs related to the premises, including costs of operations, maintenance, repair, replacement, and management of the leased premises, which it began paying simultaneous with the rent commencement date in March 2020. As of September 30, 2022, 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, which is classified as restricted cash on the condensed consolidated balance sheets.

Preferred Stock and Common Stoc

Preferred Stock and Common Stock	9 Months Ended
Preferred Stock and Common Stock	Sep. 30, 2022
Preferred Stock and Common Stock
Preferred Stock and Common Stock	8. Preferred Stock and Common Stock Undesignated Preferred Stock As of September 30, 2022 and December 31, 2021, the Company’s certificate of incorporation, as amended, authorized the Company to issue up to 5,000,000 shares of undesignated preferred stock at $0.0001 par value per share. Convertible Preferred Stock 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, 2022 and December 31, 2021, the Company’s certificate of incorporation, as amended, authorized the Company to issue up to 200,000,000 shares of common stock, $0.0001 par value per share. Shares Reserved for Future Issuance As of September 30, 2022 and December 31, 2021, the Company had reserved shares of common stock for future issuance, including under the Company’s 2020 Stock Incentive Plan (as amended, the “2020 Plan”), 2021 Stock Incentive Plan (the “2021 Plan”) and 2021 Employee Stock Purchase Plan (the “2021 ESPP”) as follows: September 30, December 31, 2022 2021 Shares of common stock reserved for exercise of a warrant 2,631 2,631 Shares of common stock reserved for exercise of outstanding stock options under the 2021 and 2020 Stock Incentive Plans 4,999,256 4,088,456 Shares of common stock reserved for future awards under the 2021 Stock Incentive Plan 2,809,865 2,349,875 Shares of common stock reserved for purchase under the 2021 Employee Stock Purchase Plan 566,720 292,031 Total shares reserved for future issuance 8,378,472 6,732,993

Equity-Based Compensation

Equity-Based Compensation	9 Months Ended
Equity-Based Compensation	Sep. 30, 2022
Equity-Based Compensation
Equity-Based Compensation	9. Equity-Based Compensation Equity Incentive Plans 2020 Stock Incentive Plan In July 2020, the Company’s stockholders approved the 2020 Plan. Under the 2020 Plan, the Company was authorized to issue shares of common stock to the Company’s employees, officers, directors, consultants, and advisors in the form of options, restricted stock awards or other stock-based awards. Upon the effectiveness of the 2021 Plan in October 2021, the Company ceased granting awards under the 2020 Plan. 2021 Stock Incentive Plan In September 2021, the Company’s board of directors adopted the 2021 Plan, which was approved by the Company’s stockholders and became effective immediately prior to the effectiveness of the Company’s registration statement on Form S-1, as amended (File No. 333-259973), which was declared effective by the SEC on October 21, 2021 (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 initially reserved for issuance under the 2021 Plan was 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 the Company’s 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 (the “Evergreen Provision”). Effective January 1, 2022, the number of shares reserved for issuance under the 2021 Plan increased by 1,373,447 shares in accordance with the Evergreen Provision. As of September 30, 2022, there were 2,809,865 shares available for future issuance under the 2021 Plan. 2021 Employee Stock Purchase Plan In September 2021, the Company’s board of directors adopted the 2021 ESPP, which was approved by the stockholders and became effective on October 21, 2021, immediately prior to the effectiveness of the Registration Statement. The Company initially reserved 292,031 shares of the Company’s common stock for future issuance under the 2021 ESPP. 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 (the “ESPP Evergreen Provision”). Effective January 1, 2022, the number of shares reserved for issuance under the 2021 ESPP increased by 274,689 shares in accordance with the ESPP Evergreen Provision. As of September 30, 2022, no offering periods have commenced under the 2021 ESPP. Equity-Based Compensation Expense During the three and nine months ended September 30, 2022 and 2021, the Company recorded compensation expense related to 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: Three Months Ended September 30, Nine Months Ended September 30, 2022 2021 2022 2021 Research and development expense $ 594 $ 378 $ 1,827 $ 864 General and administrative expense 1,277 713 4,782 2,023 Total equity-based compensation expense $ 1,871 $ 1,091 $ 6,609 $ 2,887 For the nine months ended September 30, 2022 and 2021, general and administrative equity-based compensation expense includes $0.6 million and $0.2 million, respectively, in non-recurring compensation expense resulting from the modification of previously issued stock options. Stock Options A summary of stock option activity under the 2021 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, 2021 4,088,456 $ 8.59 9.13 $ 30,291 Granted 1,610,916 $ 8.35 Exercised (2,657) $ 5.89 Cancelled/forfeited (697,459) $ 10.23 Outstanding as of September 30, 2022 4,999,256 $ 8.29 8.54 $ 134 Exercisable as of September 30, 2022 1,601,562 $ 7.93 7.60 $ 1 Vested and expected to vest as of September 30, 2022 4,999,256 $ 8.29 8.54 $ 134 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, 2022 and 2021 was $5.88 and $5.16, respectively. The following assumptions were used in determining the fair value of options granted during the nine months ended September 30, 2022 and 2021: Nine Months Ended September 30, 2022 2021 Risk-free interest rate 1.47 – 3.63 % 0.63 – 1.15 % Expected dividend yield 0 % 0 % Expected term (in years) 5.27 – 6.08 5.52 – 10.00 Expected volatility 80.75 – 87.64 % 80.60 – 85.26 % The achievement of the performance conditions underlying outstanding performance-based awards was not probable as of September 30, 2022; therefore, no compensation expense was recorded for these awards. As of September 30, 2022, total unrecognized compensation costs related to performance-based awards was less than $0.1 million. As of September 30, 2022, total unrecognized compensation cost related to unvested stock options, excluding performance-based awards, was approximately $18.4 million, which is expected to be recognized over a weighted-average period of 2.76 years. 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, 2021 110,575 $ 5.51 Vested (46,117) $ 5.51 Canceled/Forfeited — $ — Unvested as of September 30, 2022 64,458 $ 5.51 In June 2020, the Company granted 552,546 shares of common stock underlying restricted stock awards, and the Company has not subsequently granted any additional restricted stock awards. During the nine months ended September 30, 2022, the aggregate fair value of the restricted stock awards that vested was $0.3 million. As of September 30, 2022, total unrecognized compensation cost related to unvested restricted stock awards was approximately $0.4 million, which is expected to be recognized over a weighted-average period of 1.13 years.

Income Taxes

Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 2022
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, 2022 and 2021. 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, 2022
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, 2022 2021 Convertible preferred stock — 18,398,248 Unvested restricted common stock 64,458 135,811 Outstanding stock options 4,999,256 3,391,136 Warrants 2,631 2,631 Total common stock equivalents 5,066,345 21,927,826

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Sep. 30, 2022
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 (“GAAP”) and pursuant to the rules and regulations of the United States Securities and Exchange Commission, (the “SEC”). Certain information and footnote disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. These condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and the notes thereto included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2021. 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. In connection with its IPO, the Company effected a 1-for-9.5
Principles of Consolidation	Principles of Consolidation The accompanying condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries: Xilio Development, Inc., a Delaware corporation and Xilio Securities Corporation, a Massachusetts corporation, created to buy, sell and hold securities. Effective as of September 30, 2022, the Company’s wholly owned subsidiaries, Xilio Therapeutics, LLC and Xilio Concerto, LLC, were merged with and into Xilio Development, Inc., with Xilio Development, Inc. as the surviving corporation. All intercompany accounts and transactions have been eliminated in consolidation.
Unaudited Interim Condensed Consolidated Financial Information	Unaudited Interim Condensed Consolidated Financial Information The accompanying condensed consolidated financial statements are unaudited. The financial data and other information contained in these notes are also unaudited. The condensed consolidated balance sheet data as of December 31, 2021 was derived from the Company’s audited consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2021. 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, 2022, the results of its operations for the three and nine months ended September 30, 2022 and 2021 and cash flows for the nine months ended September 30, 2022 and 2021. 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, 2021, and the notes thereto, included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2021. The results for the three and nine months ended September 30, 2022 are not necessarily indicative of results to be expected for the year ended December 31, 2022, 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, the valuation of equity-based compensation, including stock options and restricted common stock, the useful life of long-lived assets and income taxes. Actual results could differ from those estimates.
Cash Equivalents and Restricted Cash	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: September 30, September 30, 2022 2021 Cash and cash equivalents $ 139,143 $ 99,767 Restricted cash 1,557 1,553 Total cash, cash equivalents and restricted cash as shown on the consolidated statement of cash flows $ 140,700 $ 101,320
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326)—Measurement of Credit Losses on Financial Instruments , as amended (“ASU 2016-13”). The provisions of ASU 2016-13 modify the impairment model to utilize an expected loss methodology in place of the previously used incurred loss methodology and require a consideration of a broader range of reasonable and supportable information to inform credit loss estimates. The Company adopted ASU 2016-13 as of January 1, 2022, and the adoption did not have a material effect on its condensed consolidated financial statements and related disclosures. In August 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470 - 20) and Derivatives and Hedging Contracts in Entity’s Own Equity (Subtopic 815 - 40) derivatives scope exception for contracts in an entity’s own equity. The Company adopted ASU 2020-06 as of January 1, 2022, and the adoption did not have a material effect on its condensed consolidated financial statements and related disclosures.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	9 Months Ended
Summary of Significant Accounting Policies (Tables)	Sep. 30, 2022
Summary of Significant Accounting Policies
Schedule of cash, cash equivalents and restricted cash	September 30, September 30, 2022 2021 Cash and cash equivalents $ 139,143 $ 99,767 Restricted cash 1,557 1,553 Total cash, cash equivalents and restricted cash as shown on the consolidated statement of cash flows $ 140,700 $ 101,320

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
Fair Value Measurements (Tables)	Sep. 30, 2022
Fair Value Measurements
Schedule of financial assets at fair value on a recurring basis	Quoted Prices in Active Significant Markets for Other Significant Identical Observable Unobservable September 30, Assets Inputs Inputs 2022 Level 1 Level 2 Level 3 Financial assets: Cash equivalents—money market funds $ 936 $ 936 $ — $ — Total financial assets $ 936 $ 936 $ — $ — Quoted Prices in Active Significant Markets for Other Significant Identical Observable Unobservable December 31, Assets Inputs Inputs 2021 Level 1 Level 2 Level 3 Financial assets: Cash equivalents—money market funds $ 8,534 $ 8,534 $ — $ — Total financial assets $ 8,534 $ 8,534 $ — $ —

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	9 Months Ended
Property and Equipment, Net (Tables)	Sep. 30, 2022
Property and Equipment, Net
Summary of property and equipment, net	September 30, December 31, 2022 2021 Laboratory equipment $ 5,433 $ 3,805 Computers and software 228 228 Furniture and fixtures 636 636 Leasehold improvements 5,124 5,124 Construction in process 95 539 Total property and equipment $ 11,516 $ 10,332 Less accumulated depreciation (3,963) (2,712) Property and equipment, net $ 7,553 $ 7,620

Accrued Expenses (Tables)

Accrued Expenses (Tables)	9 Months Ended
Accrued Expenses (Tables)	Sep. 30, 2022
Accrued Expenses
Summary of accrued expenses	September 30, December 31, 2022 2021 External research and development $ 4,306 $ 2,794 Personnel-related 3,728 5,145 Professional and consulting fees 764 491 Other 264 321 Total accrued expenses $ 9,062 $ 8,751

Loan and Security Agreement (Ta

Loan and Security Agreement (Tables)	9 Months Ended
Loan and Security Agreement (Tables)	Sep. 30, 2022
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 as of September 30, 2022: Minimum Loan Payments 2022 $ — 2023 6,667 2024 3,333 Total future principal payments 10,000 Less: unamortized discount (219) Total notes payable $ 9,781

Preferred Stock and Common St_2

Preferred Stock and Common Stock (Tables)	9 Months Ended
Preferred Stock and Common Stock (Tables)	Sep. 30, 2022
Preferred Stock and Common Stock
Schedule of Shares Reserved for Future Issuance	September 30, December 31, 2022 2021 Shares of common stock reserved for exercise of a warrant 2,631 2,631 Shares of common stock reserved for exercise of outstanding stock options under the 2021 and 2020 Stock Incentive Plans 4,999,256 4,088,456 Shares of common stock reserved for future awards under the 2021 Stock Incentive Plan 2,809,865 2,349,875 Shares of common stock reserved for purchase under the 2021 Employee Stock Purchase Plan 566,720 292,031 Total shares reserved for future issuance 8,378,472 6,732,993

Equity-Based Compensation (Tabl

Equity-Based Compensation (Tables)	9 Months Ended
Equity-Based Compensation (Tables)	Sep. 30, 2022
Equity-Based Compensation
Schedule of recorded compensation expense related to incentive units, stock options, and restricted common stock	Three Months Ended September 30, Nine Months Ended September 30, 2022 2021 2022 2021 Research and development expense $ 594 $ 378 $ 1,827 $ 864 General and administrative expense 1,277 713 4,782 2,023 Total equity-based compensation expense $ 1,871 $ 1,091 $ 6,609 $ 2,887
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, 2021 4,088,456 $ 8.59 9.13 $ 30,291 Granted 1,610,916 $ 8.35 Exercised (2,657) $ 5.89 Cancelled/forfeited (697,459) $ 10.23 Outstanding as of September 30, 2022 4,999,256 $ 8.29 8.54 $ 134 Exercisable as of September 30, 2022 1,601,562 $ 7.93 7.60 $ 1 Vested and expected to vest as of September 30, 2022 4,999,256 $ 8.29 8.54 $ 134
Schedule of assumptions used in determining the fair value of options granted to employees	Nine Months Ended September 30, 2022 2021 Risk-free interest rate 1.47 – 3.63 % 0.63 – 1.15 % Expected dividend yield 0 % 0 % Expected term (in years) 5.27 – 6.08 5.52 – 10.00 Expected volatility 80.75 – 87.64 % 80.60 – 85.26 %
Schedule of company's restricted stock activity	Number Weighted of Shares Average of Restricted Grant Date Stock Fair Value Unvested as of December 31, 2021 110,575 $ 5.51 Vested (46,117) $ 5.51 Canceled/Forfeited — $ — Unvested as of September 30, 2022 64,458 $ 5.51

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	9 Months Ended
Net Loss Per Share (Tables)	Sep. 30, 2022
Net Loss Per Share
Schedule of antidilutive securities excluded from computation of diluted net loss per share	Nine Months Ended September 30, 2022 2021 Convertible preferred stock — 18,398,248 Unvested restricted common stock 64,458 135,811 Outstanding stock options 4,999,256 3,391,136 Warrants 2,631 2,631 Total common stock equivalents 5,066,345 21,927,826

Description of Business, Init_2

Description of Business, Initial Public Offering and Liquidity and Capital Resources - IPO (Details) - Common Stock $ / shares in Units, $ in Millions	3 Months Ended
	Dec. 31, 2021 USD ($) $ / shares shares
IPO
Sale of stock
Number of shares issued and sold	8,119,106
Offering price (in dollar per share) \| $ / shares	$ 16
Net proceeds received \| $	$ 116.4
Over-Allotment Option
Sale of stock
Number of shares issued and sold	766,106

Description of Business, Init_3

Description of Business, Initial Public Offering and Liquidity and Capital Resources - Liquidity and Capital Resources (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021
Description of Business, Initial Public Offering and Liquidity and Capital Resources
Cash and cash equivalents	$ 139,143	$ 198,053	$ 99,767
Substantial doubt about going concern within one year	false

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Reverse Stock Split (Details)	Oct. 15, 2021
Summary of Significant Accounting Policies
Reverse stock split	0.1053

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Dec. 31, 2020
Summary of Significant Accounting Policies
Cash and cash equivalents	$ 139,143	$ 198,053	$ 99,767
Restricted cash	1,557	1,553	1,553
Total cash, cash equivalents and restricted cash as shown on the consolidated statement of cash flows	$ 140,700	$ 199,606	$ 101,320	$ 20,789

Fair Value Measurements - Finan

Fair Value Measurements - Financial assets at fair value on a recurring basis (Details) - Recurring basis - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Financial assets:
Total financial assets	$ 936	$ 8,534
Cash equivalents-money market funds
Financial assets:
Total financial assets	936	8,534
Level 1
Financial assets:
Total financial assets	936	8,534
Level 1 \| Cash equivalents-money market funds
Financial assets:
Total financial assets	$ 936	$ 8,534

Fair Value Measurements - Trans

Fair Value Measurements - Transfers between levels (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
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

Property and Equipment, Net (De

Property and Equipment, Net (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Property and Equipment
Property and equipment	$ 11,516		$ 10,332
Less accumulated depreciation	(3,963)		(2,712)
Property and equipment, net	7,553		7,620
Depreciation	1,300	$ 1,000
Laboratory equipment
Property and Equipment
Property and equipment	5,433		3,805
Computers and software
Property and Equipment
Property and equipment	228		228
Furniture & fixtures
Property and Equipment
Property and equipment	636		636
Leasehold improvements
Property and Equipment
Property and equipment	5,124		5,124
Construction in process
Property and Equipment
Property and equipment	$ 95		$ 539

Accrued Expenses (Details)

Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Accrued Expenses
External research and development	$ 4,306	$ 2,794
Personnel related	3,728	5,145
Professional and consulting services	764	491
Other	264	321
Total accrued expenses	$ 9,062	$ 8,751

Loan and Security Agreement - D

Loan and Security Agreement - Description (Details) - Loan Agreement and Amended Loan Agreement $ in Millions	1 Months Ended
	Oct. 31, 2021 USD ($)	Nov. 30, 2019 USD ($) loan	Sep. 30, 2022
Loan and security agreement
Borrowed amount		$ 10
Additional borrowing capacity		$ 10
Interest rate at end of period (as a percent)			6.50%
Fee paid upon closing of IPO	$ 0.8
Additional interest rate upon event of default (as a percent)		5%
Minimum
Loan and security agreement
Number of additional term loans that may be requested \| loan		1
Stated interest rate		4.75%
Prime rate
Loan and security agreement
Basis spread (as percent)		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, 2022	Sep. 30, 2021
Minimum aggregate future loan payments
2023	$ 6,667
2024	3,333
Total future principal payments	10,000
Less: unamortized discount	(219)
Total notes payable	9,781
Interest expense	$ 500	$ 500

Commitments and Contingencies -

Commitments and Contingencies - Lease information (Details) $ in Millions	1 Months Ended
	Aug. 31, 2019 ft²	Sep. 30, 2022 USD ($)
Commitments and Contingencies
Area leased (in square feet) \| ft²	27,830
Option to extend	true
Term of option to extend	5 years
Letter of credit for the benefit of landlord \| $		$ 1.6

Preferred Stock and Common St_3

Preferred Stock and Common Stock - Authorized (Details) - $ / shares	1 Months Ended
	Oct. 31, 2021	Sep. 30, 2022	Dec. 31, 2021
Preferred stock and Common stock
Preferred stock, shares authorized		5,000,000	5,000,000
Preferred stock, par value (in dollars per share)		$ 0.0001	$ 0.0001
Common stock, shares authorized		200,000,000	200,000,000
Common stock, par value (in dollars per share)		$ 0.0001	$ 0.0001
Common Stock
Preferred stock and Common stock
Conversion of convertible preferred stock into common stock upon initial public offering (in shares)	18,398,248

Preferred Stock and Common St_4

Preferred Stock and Common Stock - Shares Reserved for Future Issuance (Details) - shares	Sep. 30, 2022	Dec. 31, 2021
Preferred Stock and Common Stock
Shares of common stock reserved for exercise of a warrant	2,631	2,631
Shares of common stock reserved for exercise of outstanding stock options under the 2021 and 2020 Stock Incentive Plans	4,999,256	4,088,456
Shares of common stock reserved for future awards under the 2021 Stock Incentive Plan	2,809,865	2,349,875
Shares of common stock reserved for purchase under the 2021 Employee Stock Purchase Plan	566,720	292,031
Total shares reserved for future issuance	8,378,472	6,732,993

Equity-Based Compensation - Equ

Equity-Based Compensation - Equity Incentive Plans (Details) - shares	Oct. 21, 2021	Sep. 30, 2022	Jan. 01, 2022	Dec. 31, 2021
Equity-Based Compensation
Common stock reserved for issuance (in shares)		8,378,472		6,732,993
2021 Stock Incentive Plan
Equity-Based Compensation
Additional common stock reserved for issuance (in shares)			1,373,447
Available for future issuance (in shares)		2,809,865
2021 Stock Incentive Plan \| Minimum
Equity-Based Compensation
Common stock reserved for issuance (in shares)	2,654,828
2021 Stock Incentive Plan \| Maximum
Equity-Based Compensation
Common stock reserved for issuance (in shares)	3,967,038
Annual increase in number of shares reserved for issuance (as a percent)	5%

Equity-Based Compensation - Emp

Equity-Based Compensation - Employee Stock Purchase Plan (Details) - shares	Jan. 01, 2022	Oct. 21, 2021	Sep. 30, 2022	Dec. 31, 2021
Equity-Based Compensation
Common stock reserved for issuance (in shares)			8,378,472	6,732,993
Employee Stock Purchase Plan
Equity-Based Compensation
Common stock reserved for issuance (in shares)		292,031
Additional common stock issuable under the plan	274,689
Employee Stock Purchase Plan \| Maximum
Equity-Based Compensation
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%

Equity-Based Compensation - E_2

Equity-Based Compensation - Equity-based compensation expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Equity-Based Compensation
Total compensation expense	$ 1,871	$ 1,091	$ 6,609	$ 2,887
Research and development expense
Equity-Based Compensation
Total compensation expense	594	378	1,827	864
General and administrative expense
Equity-Based Compensation
Total compensation expense	$ 1,277	$ 713	4,782	2,023
Non-recurring compensation expense			$ 600	$ 200

Equity-Based Compensation - Sto

Equity-Based Compensation - Stock option activity (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2022	Dec. 31, 2021
Options Outstanding
Outstanding at beginning of period (in shares)	4,088,456
Granted (in shares)	1,610,916
Exercised (in shares)	(2,657)
Cancelled/forfeited (in shares)	(697,459)
Outstanding at end of period (in shares)	4,999,256	4,088,456
Exercisable at end of period (in shares)	1,601,562
Vested and expected to vest at end of period (in shares)	4,999,256
Weighted Average Exercise Price
Outstanding (in dollars per share)	$ 8.29	$ 8.59
Granted (in dollars per share)	8.35
Exercised (in dollars per share)	5.89
Cancelled/forfeited (in dollars per share)	10.23
Exercisable at end of period (in dollars per share)	7.93
Vested and expected to vest at end of period (in dollars per share)	$ 8.29
Weighted Average Remaining Contractual Term (In years)
Outstanding (in years)	8 years 6 months 14 days	9 years 1 month 17 days
Exercisable at end of period (in years)	7 years 7 months 6 days
Vested and expected to vest at end of period (in years)	8 years 6 months 14 days
Aggregate Intrinsic Value
Outstanding (in dollars)	$ 134	$ 30,291
Exercisable (in dollars)	1
Vested and expected to vest (in dollars)	$ 134

Equity-Based Compensation - S_2

Equity-Based Compensation - Stock options, fair value assumptions (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Equity-Based Compensation
Fair value of options granted (in dollars per share)			$ 5.88	$ 5.16
Stock options granted during the period (in shares)			1,610,916
Equity-based compensation expense	$ 1,871	$ 1,091	$ 6,609	$ 2,887
Stock options
Equity-Based Compensation
Risk-free interest rate, minimum (as a percent)			1.47%	0.63%
Risk-free interest rate, maximum (as a percent)			3.63%	1.15%
Expected dividend yield (as a percent)			0%	0%
Expected volatility, minimum (as percentage)			80.75%	80.60%
Expected volatility, maximum (as percentage)			87.64%	85.26%
Stock options \| Minimum
Equity-Based Compensation
Expected term (in years)			5 years 3 months 7 days	5 years 6 months 7 days
Stock options \| Maximum
Equity-Based Compensation
Expected term (in years)			6 years 29 days	10 years
Stock options, excluding performance-based awards
Equity-Based Compensation
Total unrecognized compensation cost	18,400		$ 18,400
Weighted-average period for unrecognized compensation cost to be recognized			2 years 9 months 3 days
Stock options, vesting based on performance
Equity-Based Compensation
Equity-based compensation expense			$ 0
Stock options, vesting based on performance \| Maximum
Equity-Based Compensation
Total unrecognized compensation cost	$ 100		$ 100

Equity-Based Compensation - Res

Equity-Based Compensation - Restricted Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Jun. 30, 2020	Sep. 30, 2022	Sep. 30, 2021
Weighted Average Grant Date Fair Value
Equity-based compensation expense	$ 1,871	$ 1,091		$ 6,609	$ 2,887
Restricted Stock
Equity Based Compensation
Outstanding at beginning of period (in shares)				110,575
Vested (in shares)				(46,117)
Outstanding at end of period (in shares)	64,458			64,458
Weighted Average Grant Date Fair Value
Outstanding at beginning of period (in dollars per share)				$ 5.51
Vested (in dollars per share)				5.51
Outstanding at end of period (in dollars per share)	$ 5.51			$ 5.51
Granted (in shares)			552,546
Aggregate fair value of restricted stock awards that vested				$ 300
Total unrecognized compensation cost of unvested restricted stock awards	$ 400			$ 400
Weighted-average period for unrecognized compensation cost to be recognized				1 year 1 month 17 days

Income Taxes - Provision (Detai

Income Taxes - Provision (Details) - USD ($) $ in Thousands	9 Months Ended
Income Taxes - Provision (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Sep. 30, 2021
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, 2022	Sep. 30, 2021
Net Loss Per Share
Total common stock equivalents	5,066,345	21,927,826
Convertible preferred stock
Net Loss Per Share
Total common stock equivalents		18,398,248
Restricted Stock
Net Loss Per Share
Total common stock equivalents	64,458	135,811
Stock options
Net Loss Per Share
Total common stock equivalents	4,999,256	3,391,136
Warrants
Net Loss Per Share
Total common stock equivalents	2,631	2,631