0001558370-23-018587 | 10-Q | XBRL Viewer

Accrued Expenses

9 Months Ended

Sep. 30, 2023

4. Accrued Expenses

Accrued expenses consist of the following as of September 30, 2023 and December 31, 2022:


	September 30,		December 31,
	2023		2022
External research and development	$	4,553	$	3,178
Personnel-related		4,051		5,413
Professional and consulting fees		627		1,536
Other		173		200
Total accrued expenses	$	9,404	$	10,327

Stock-Based Compensation - Stock option activity (Details) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2023 $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares
Options Outstanding
Outstanding at beginning of period (in shares)	4,960,553
Granted (in shares)	3,738,555
Exercised (in shares)	(2,757)
Cancelled/forfeited (in shares)	(872,873)
Outstanding at end of period (in shares)	7,823,478	4,960,553
Exercisable at end of period (in shares)	2,768,685
Weighted Average Exercise Price
Outstanding (in dollars per share) \| $ / shares	$ 5.66	$ 8.04
Granted (in dollars per share) \| $ / shares	2.75
Exercised (in dollars per share) \| $ / shares	2.82
Cancelled/forfeited (in dollars per share) \| $ / shares	6.77
Exercisable at end of period (in dollars per share) \| $ / shares	$ 7.19
Weighted Average Remaining Contractual Term (In years)
Outstanding (in years)	8 years 6 months 14 days	8 years 7 months 2 days
Exercisable at end of period (in years)	7 years 7 months 28 days
Aggregate Intrinsic Value
Outstanding (in dollars) \| $		$ 89

Collaboration Agreements	9 Months Ended
Sep. 30, 2023
Collaboration Agreements
Collaboration Agreements	6. Collaboration Agreements In July 2023, the Company and F. Hoffmann-La Roche Ltd. (“Roche”) entered into a clinical trial collaboration (the “Roche Clinical Collaboration”) pursuant to a clinical supply agreement to evaluate XTX101 in combination with atezolizumab (Tecentriq®) in a Phase 1/2 clinical trial consisting of a Phase 1 dose escalation portion assessing the combination in patients with advanced solid tumors and a Phase 2 portion assessing the combination in patients with microsatellite stable colorectal cancer. Under the clinical supply agreement, the Company is eligible to receive specified cost-sharing payments from Roche, and each company will supply its respective anti-cancer agent to support the Phase 1/2 clinical trial. The Company will sponsor and conduct the Phase 1/2 clinical trial and retains global development and commercialization rights to XTX101. The Company concluded that the cost-sharing payments from the Roche Clinical Collaboration are not in the scope of ASC 606 because the Company does not consider performing research and development services for reimbursement to be part of its ongoing major or central operations. Therefore, the Company applied a reasonable, rational, and consistently applied accounting policy election to record the cost-sharing payments from the Roche Clinical Collaboration as a reduction of research and development expenses in the condensed consolidated statements of operations and comprehensive loss for the period in which a study development event is achieved. During the three and nine months ended September 30, 2023, the Company recognized a reduction of research and development expenses of $2.0 million. As of September 30, 2023, $2.0 million of earned but unpaid cost-sharing payments were included in prepaid expenses and other current assets of the Company’s condensed consolidated balance sheets.

Collaboration Agreements

9 Months Ended

Sep. 30, 2023

Collaboration Agreements

Collaboration Agreements

6. Collaboration Agreements

In July 2023, the Company and F. Hoffmann-La Roche Ltd. (“Roche”) entered into a clinical trial collaboration (the “Roche Clinical Collaboration”) pursuant to a clinical supply agreement to evaluate XTX101 in combination with atezolizumab (Tecentriq®) in a Phase 1/2 clinical trial consisting of a Phase 1 dose escalation portion assessing the combination in patients with advanced solid tumors and a Phase 2 portion assessing the combination in patients with microsatellite stable colorectal cancer.

Under the clinical supply agreement, the Company is eligible to receive specified cost-sharing payments from Roche, and each company will supply its respective anti-cancer agent to support the Phase 1/2 clinical trial. The Company will sponsor and conduct the Phase 1/2 clinical trial and retains global development and commercialization rights to XTX101.

The Company concluded that the cost-sharing payments from the Roche Clinical Collaboration are not in the scope of ASC 606 because the Company does not consider performing research and development services for reimbursement to be part of its ongoing major or central operations. Therefore, the Company applied a reasonable, rational, and consistently applied accounting policy election to record the cost-sharing payments from the Roche Clinical Collaboration as a reduction of research and development expenses in the condensed consolidated statements of operations and comprehensive loss for the period in which a study development event is achieved. During the three and nine months ended September 30, 2023, the Company recognized a reduction of research and development expenses of $2.0 million. As of September 30, 2023, $2.0 million of earned but unpaid cost-sharing payments were included in prepaid expenses and other current assets of the Company’s condensed consolidated balance sheets.

Property and Equipment, Net

9 Months Ended

Sep. 30, 2023

Property and Equipment, Net

Property and Equipment, Net

3. Property and Equipment, Net

Property and equipment, net consists of the following as of September 30, 2023 and December 31, 2022:


	September 30,		December 31,
	2023		2022
Laboratory equipment	$	6,091	$	5,587
Computers and software		183		228
Furniture and fixtures		681		636
Leasehold improvements		5,124		5,124
Construction in process		—		98
Total property and equipment		12,079		11,673
Less: accumulated depreciation		(5,713)		(4,418)
Property and equipment, net	$	6,366	$	7,255

The Company recognized depreciation and amortization expense related to property and equipment of $1.4 million and $1.3 million for the nine months ended September 30, 2023 and 2022, respectively.

Stock-Based Compensation - Restricted Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Weighted Average Grant Date Fair Value
Stock-based compensation expense		$ 1,861	$ 1,871	$ 5,452	$ 6,609
Restricted stock
Equity Based Compensation
Outstanding at beginning of period (in shares)				46,160
Vested (in shares)				(31,793)
Canceled/Forfeited (in shares)				(1,293)
Outstanding at end of period (in shares)		13,074		13,074
Weighted Average Grant Date Fair Value
Outstanding at beginning of period (in dollars per share)				$ 5.51
Vested (in dollars per share)				5.51
Cancelled/forfeited (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				$ 100	$ 300
Total unrecognized stock-based compensation expense		$ 100		$ 100
Weighted-average period for unrecognized compensation expense to be recognized				4 months 24 days

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Cash flows from operating activities:
Net loss	$ (58,749)	$ (65,756)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,451	1,358
Non-cash interest expense	141	164
Stock-based compensation expense	5,452	6,609
Loss on disposal of property and equipment	3	1
Changes in operating assets and liabilities:
Prepaid and other assets	(597)	1,283
Operating lease right-of-use asset	338	288
Accounts payable	(1,625)	(972)
Accrued expenses and other liabilities	(928)	116
Operating lease liability	(679)	(591)
Net cash used in operating activities	(55,193)	(57,500)
Cash flows from investing activities:
Purchases of property and equipment	(486)	(1,358)
Net cash used in investing activities	(486)	(1,358)
Cash flows from financing activities:
Repayments of debt principal	(5,000)
Payments of finance lease	(64)	(64)
Proceeds from issuance of common stock under employee stock purchase plan	140
Proceeds from exercise of stock options	8	16
Net cash used in financing activities	(4,916)	(48)
Decrease in cash, cash equivalents and restricted cash	(60,595)	(58,906)
Cash, cash equivalents and restricted cash, beginning of period	121,947	199,606
Cash, cash equivalents and restricted cash, end of period	61,352	140,700
Supplemental cash flow disclosure:
Cash paid for interest	474	380
Supplemental disclosure of non-cash activities:
Capital expenditures included in accounts payable or accrued expenses		371
Reconciliation to amounts within the condensed consolidated balance sheets:
Cash and cash equivalents	59,772	139,143
Restricted cash	1,580	1,557
Cash, cash equivalents and restricted cash, end of period	$ 61,352	$ 140,700

Loan and Security Agreement

9 Months Ended

Sep. 30, 2023

Loan and Security Agreement

Loan and Security Agreement

5. Loan and Security Agreement

In November 2019, the Company’s wholly owned subsidiary, Xilio Development, Inc. (“Borrower”), entered into a loan and security agreement (as amended and restated in May 2023, the “Loan Agreement”) with Pacific Western Bank (“PacWest”), with the Company as a guarantor. Under the Loan Agreement, in November 2019, the Borrower borrowed $10.0 million under a term loan. Interest on amounts outstanding under the Loan Agreement accrues 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, 2023, the interest rate on the term loan was 8.75%. The Borrower was required to make interest-only payments on any outstanding balances through December 31, 2022. The Borrower commenced making equal monthly payments of principal plus interest in January 2023, and it will be required to make such payments until the term loan matures on June 30, 2024.

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 Borrower granted PacWest a first priority security interest on substantially all of the Borrower’s assets, excluding intellectual property, subject to certain exceptions.

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, 2023, the Company and Borrower were in compliance with all covenants under the Loan Agreement.

The Borrower has the following minimum aggregate future loan principal payments under the Loan Agreement as of September 30, 2023:


	Minimum Loan
	Payments
2023 (remaining three months)	$	1,667
2024		3,333
Total future principal payments		5,000
Less: unamortized discount		(43)
Total note payable	$	4,957

The Company recognized $0.6 million and $0.5 million of interest expense related to the Loan Agreement for the nine months ended September 30, 2023 and 2022, respectively, which is reflected in other income, net on the condensed consolidated statements of operations and comprehensive loss.

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References

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+ Details

Commitments and Contingencies

9 Months Ended

Sep. 30, 2023

Commitments and Contingencies

Commitments and Contingencies

7. Commitments and Contingencies

The Company has an operating lease for its headquarters and a finance lease for certain lab equipment. In August 2019, the Company entered into a facility lease agreement with a landlord providing funding for tenant improvements and occupancy of approximately 27,830 square feet of office and laboratory space (the “premises”) 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 an additional term 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, 2023 and December 31, 2022, the Company had a letter of credit for the benefit of its landlord in the amount of $1.6 million, collateralized by a money market account, which is recorded as restricted cash on the condensed consolidated balance sheets.

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 2023	Dec. 31, 2022
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	27,542,000	27,471,607
Common stock, shares outstanding	27,528,926	27,425,447

Commitments and Contingencies (Details) $ in Millions	1 Months Ended
Commitments and Contingencies (Details) $ in Millions	Aug. 31, 2019 ft²	Sep. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
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	$ 1.6

Stock-Based Compensation - Stock Incentive Plans (Details) - shares		1 Months Ended
	Jan. 01, 2023	Oct. 31, 2021	Sep. 30, 2023	Dec. 31, 2022
Stock-Based Compensation
Common stock reserved for issuance (in shares)			10,231,375	8,653,472
2021 Plan
Stock-Based Compensation
Additional common stock reserved under the plan (in shares)	1,373,580
Shares available for future issuance (in shares)			1,412,759
2021 Plan \| Minimum
Stock-Based Compensation
Common stock reserved for issuance (in shares)		2,654,828
2021 Plan \| Maximum
Stock-Based Compensation
Additional common stock to be reserved for issuance (in shares)		3,967,038
Annual increase in number of shares reserved for issuance (as a percent)		5.00%

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Reference 28: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(v)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

+ Details

Description of Business and Liquidity and Going Concern

9 Months Ended

Sep. 30, 2023

Description of Business and Liquidity and Going Concern

Description of Business and Liquidity and Going Concern

1. Description of Business and Liquidity and Going Concern

Description of Business

Xilio Therapeutics, Inc. (“Xilio” or the “Company”) is a clinical-stage biotechnology company dedicated to discovering and developing tumor-activated immuno-oncology (“I-O”) therapies with the goal of significantly improving outcomes for people living with cancer without the systemic side effects of current I-O treatments. The Company was incorporated in Delaware in June 2020, and its headquarters are located in Waltham, Massachusetts.

Liquidity and Going Concern

Since its inception, the Company has devoted substantially all of its financial resources and efforts to research and development activities. As of September 30, 2023, the Company had an accumulated deficit of $307.9 million and has incurred significant operating losses, including net losses of $58.7 million and $65.8 million for the nine months ended September 30, 2023 and 2022, respectively. The Company expects its operating losses and negative operating cash flows to continue for the foreseeable future as it continues to advance its product candidates through clinical trials, maintains the infrastructure necessary to support these activities and continues to incur costs associated with operating as a public company. The Company anticipates its existing cash and cash equivalents of $59.8 million as of September 30, 2023 will not be sufficient to enable the Company to fund its current operating plan and capital expenditure requirements for at least twelve months from the date of issuance of these condensed consolidated financial statements. These factors raise substantial doubt about the Company’s ability to continue as a going concern.

To continue to fund the operations of the Company, management has developed plans, which in the near term primarily consist of raising additional capital through one or more of the following: equity or debt financings; collaborations, partnerships or licensing transactions; or other sources. However, there can be no assurance that the Company will be able to complete any such transaction on acceptable terms or otherwise, and the Company may be unable to obtain sufficient additional capital. If the Company is not able to secure sufficient additional capital in the near term, the Company will need to implement cost reduction strategies, which could include delaying, limiting, reducing or eliminating both internal and external costs related to its operations and research and development programs. In addition, if the Company’s efforts to secure sufficient additional capital in the near term are unsuccessful, the Company may in the future need to seek to engage in one or more other strategic alternatives, including without limitation, the sale or divestiture of some or all of its assets or proprietary technologies.

The accompanying condensed consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the ordinary course of business. The condensed consolidated financial statements do not include any adjustments relating to the recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might result from the outcome of this uncertainty.

Net Loss Per Share

9 Months Ended

Sep. 30, 2023

Net Loss Per Share

Net Loss Per Share

10. 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,
	2023	2022
Unvested restricted common stock	13,074	64,458
Outstanding stock options	7,823,478	4,999,256
Warrants	2,631	2,631
Unvested employee stock purchase plan shares	60,488	—
Total common stock equivalents	7,899,671	5,066,345

Preferred Stock and Common Stock - Authorized (Details) - $ / shares	Sep. 30, 2023	Dec. 31, 2022
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
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, shares authorized	200,000,000	200,000,000
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001

Stock-Based Compensation - 2022 Inducement Plan (Details) - shares	9 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Stock-Based Compensation
Common stock reserved for issuance (in shares)	10,231,375	8,653,472
Stock options granted during the period (in shares)	3,738,555
2022 Inducement Plan
Stock-Based Compensation
Shares available for future issuance (in shares)	220,000
2022 Inducement Plan \| Future Awards
Stock-Based Compensation
Common stock reserved for issuance (in shares)	220,000	275,000

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2023	Nov. 07, 2023
Document and Entity Information [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2023
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		27,542,000
Entity Central Index Key	0001840233
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Amendment Flag	false

Net Loss Per Share (Tables)

9 Months Ended

Sep. 30, 2023

Net Loss Per Share

Schedule of antidilutive securities excluded from computation of diluted net loss per share


	Nine Months Ended
	September 30,
	2023	2022
Unvested restricted common stock	13,074	64,458
Outstanding stock options	7,823,478	4,999,256
Warrants	2,631	2,631
Unvested employee stock purchase plan shares	60,488	—
Total common stock equivalents	7,899,671	5,066,345

Stock-Based Compensation - Stock options, fair value assumptions (Details) - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Stock-Based Compensation
Fair value of options granted (in dollars per share)	$ 2.02	$ 5.88
Stock options
Stock-Based Compensation
Risk-free interest rate, minimum (as a percent)	3.57%	1.47%
Risk-free interest rate, maximum (as a percent)	4.40%	3.63%
Expected dividend yield (as a percent)	0.00%	0.00%
Expected volatility, minimum (as percentage)	81.69%	80.75%
Expected volatility, maximum (as percentage)	87.32%	87.64%
Unrecognized stock-based compensation expense	$ 14.3
Weighted-average period for unrecognized compensation expense to be recognized	2 years 3 months 18 days
Stock options \| Minimum
Stock-Based Compensation
Expected term (in years)	5 years 6 months	5 years 3 months 7 days
Stock options \| Maximum
Stock-Based Compensation
Expected term (in years)	6 years 29 days	6 years 29 days

Summary of Significant Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Sep. 30, 2023
Summary of Significant Accounting Policies
Basis of Presentation	Basis of Presentation The Company’s unaudited interim condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative U.S. GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASUs”) of the Financial Accounting Standards Board (“FASB”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted from this report, as is permitted by such rules and regulations. Accordingly, these unaudited interim condensed consolidated financial statements should be read in conjunction with the audited financial statements as of and for the year ended December 31, 2022 and notes thereto, included in the Company’s Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission (“SEC”) on March 2, 2023. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited financial statements. In the opinion of the Company’s management, the unaudited interim condensed consolidated financial statements contain all adjustments which are necessary to present fairly the Company’s financial position as of September 30, 2023 and the results of its operations for the three and nine months ended September 30, 2023 and 2022 and cash flows for the nine months ended September 30, 2023 and 2022. Such adjustments are of a normal and recurring nature. The results for the three and nine months ended September 30, 2023 are not necessarily indicative of the results for the year ending December 31, 2023 or for any future period.
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 security corporation. All intercompany accounts and transactions have been eliminated in consolidation.
Collaboration Agreements	Collaboration Agreements The Company analyzes its collaboration agreements to assess whether such arrangements involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards dependent on the commercial success of such activities and therefore within the scope of ASC Topic 808, Collaborative Arrangements (“ASC 808”). For arrangements within the scope of ASC 808 that contain multiple elements, the Company first determines which elements of the collaboration are deemed to be within the scope of ASC 808 and which elements of the collaboration are more reflective of a vendor-customer relationship and therefore within the scope of ASC Topic 606, Revenue from Contracts with Customers (“ASC 606”). For elements of collaboration arrangements that are accounted for pursuant to ASC 808, an appropriate recognition method is determined and applied consistently, either by analogy to authoritative accounting literature or by applying a reasonable and rational policy election. For collaboration agreements where the Company is reimbursed for a portion of its research and development expenses or participates in the cost-sharing of such research and development expenses, such reimbursements and cost-sharing arrangements are reflected as a reduction of research and development expenses in the Company’s condensed consolidated statements of operations and comprehensive loss, as the Company does not consider performing research and development services for reimbursement to be a part of its ongoing major or central operations.
Concentrations of Credit Risk	Concentrations of Credit Risk Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash and cash equivalents. The Company holds all cash and cash equivalents at accredited financial institutions. Bank accounts in the United States are generally insured by the Federal Deposit Insurance Corporation (“FDIC”) up to $250,000. Substantially all of the Company’s cash and cash equivalents are FDIC insured, including funds held through an insured cash sweep program. The Company has not experienced any losses in its cash and cash equivalents and does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships.

Accrued Expenses (Tables)

9 Months Ended

Sep. 30, 2023

Accrued Expenses

Summary of accrued expenses


	September 30,		December 31,
	2023		2022
External research and development	$	4,553	$	3,178
Personnel-related		4,051		5,413
Professional and consulting fees		627		1,536
Other		173		200
Total accrued expenses	$	9,404	$	10,327

Preferred Stock and Common Stock - Shares Reserved for Future Issuance (Details) - shares	Sep. 30, 2023	Dec. 31, 2022	Oct. 31, 2021
Shares for future issuance
Shares reserved for future issuance (in shares)	10,231,375	8,653,472
2020 Plan, 2021 Plan and 2022 Inducement Plan \| Outstanding stock options
Shares for future issuance
Shares reserved for future issuance (in shares)	7,823,478	4,960,553
2021 Plan \| Future Awards
Shares for future issuance
Shares reserved for future issuance (in shares)	1,412,759	2,848,568
2022 Inducement Plan \| Future Awards
Shares for future issuance
Shares reserved for future issuance (in shares)	220,000	275,000
2021 ESPP
Shares for future issuance
Shares reserved for future issuance (in shares)	772,507	566,720	292,031
Warrants
Shares for future issuance
Shares reserved for future issuance (in shares)	2,631	2,631

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Property and Equipment, Net (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Property and Equipment
Property and equipment	$ 12,079		$ 11,673
Less accumulated depreciation	(5,713)		(4,418)
Property and equipment, net	6,366		7,255
Depreciation	1,400	$ 1,300
Laboratory equipment
Property and Equipment
Property and equipment	6,091		5,587
Computers and software
Property and Equipment
Property and equipment	183		228
Furniture & fixtures
Property and Equipment
Property and equipment	681		636
Leasehold improvements
Property and Equipment
Property and equipment	$ 5,124		5,124
Construction in process
Property and Equipment
Property and equipment			$ 98

Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Accrued Expenses
External research and development	$ 4,553	$ 3,178
Personnel related	4,051	5,413
Professional and consulting services	627	1,536
Other	173	200
Total accrued expenses	$ 9,404	$ 10,327

Stock-Based Compensation

9 Months Ended

Sep. 30, 2023

Stock-Based Compensation

Stock-Based Compensation

9. Stock-Based Compensation

Equity Incentive Plans

2020 Stock Incentive 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.

2021 Stock Incentive Plan

In 2021, the Company’s board of directors and stockholders adopted the 2021 Plan, which became effective immediately prior to the IPO in October 2021. Upon effectiveness of the 2021 Plan, the Company ceased granting awards under the 2020 Plan. 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 2021 Plan 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 the Company 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. On January 1, 2023, the number of shares reserved for issuance under the 2021 Plan automatically increased by 1,373,580 shares.

As of September 30, 2023, there were 1,412,759 shares available for future issuance under the 2021 Plan.

2022 Inducement Plan

In 2022, the Company’s board of directors adopted the 2022 Inducement Plan pursuant to Nasdaq Rule 5635(c)(4). In accordance with Rule 5635(c)(4), stock-based incentive awards under the 2022 Inducement Plan may only be made to a newly hired employee who has not previously been a member of the Company’s board of directors, or an employee who is being rehired following a bona fide period of non-employment by the Company as a material inducement to the employee’s entering into employment with the Company. An aggregate of 275,000 shares of the Company’s common stock has been reserved for issuance under the 2022 Inducement Plan.

The exercise price of stock options granted under the 2022 Inducement Plan will not be less than the fair market value of a share of the Company’s common stock on the grant date. Other terms of awards, including vesting requirements, are determined by the Company’s board of directors and are subject to the provisions of the 2022 Inducement Plan.

As of September 30, 2023, there were 220,000 shares available for future issuance under the 2022 Inducement Plan.

2021 Employee Stock Purchase Plan

In 2021, the Company’s board of directors and stockholders adopted the 2021 ESPP, which became effective immediately prior to the IPO in October 2021. The Company initially reserved 292,031 shares of common stock for issuance under the 2021 ESPP. In addition, the 2021 ESPP provides that the number of shares of common stock reserved for issuance under the 2021 ESPP will be cumulatively increased on January 1 of each calendar year 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. On January 1, 2023, the number of shares reserved for issuance under the 2021 ESPP was increased by 274,716 shares. Offering periods under the 2021 ESPP commence on each June 1 and December 1, and end on the following November 30 and May 31, respectively. During the nine months ended September 30, 2023, 68,929 shares were purchased under the 2021 ESPP. During the nine months ended September 30, 2022, no shares were purchased under the 2021 ESPP.

As of September 30, 2023, there were 772,507 shares available for future issuance under the 2021 ESPP.

Stock-Based Compensation Expense

During the three and nine months ended September 30, 2023 and 2022, the Company recorded compensation expense related to stock options, restricted common stock and ESPP share purchases 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,
	2023		2022		2023		2022
Research and development expense	$	548	$	594	$	1,670	$	1,827
General and administrative expense		1,313		1,277		3,782		4,782
Total stock-based compensation expense	$	1,861	$	1,871	$	5,452	$	6,609

Stock Options

A summary of stock option activity under the Company’s 2020 Plan, 2021 Plan and 2022 Inducement Plan is as follows:


				Weighted
				Average
				Remaining	Aggregate
		Weighted		Contractual	Intrinsic
	Number of	Average		Term	Value (1)
	Stock Options	Exercise Price		(In years)	(In thousands)
Outstanding as of December 31, 2022	4,960,553	$	8.04	8.59	$	89
Granted	3,738,555	$	2.75
Exercised	(2,757)	$	2.82
Cancelled/forfeited	(872,873)	$	6.77
Outstanding as of September 30, 2023	7,823,478	$	5.66	8.54	$	-
Exercisable as of September 30, 2023	2,768,685	$	7.19	7.66	$	-

(1)

The aggregate intrinsic value of stock options is calculated as the difference between the exercise price of the stock options and the fair value of the Company’s common stock for those stock options that had exercise prices lower than the fair value of the Company’s common stock as of the end of the period.

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, 2023 and 2022 was $2.02 and $5.88, respectively. The following assumptions were used in determining the fair value of options granted during the nine months ended September 30, 2023 and 2022:


	Nine Months Ended September 30,
	2023			2022
Risk-free interest rate		3.57 - 4.40	%		1.47 – 3.63	%
Expected dividend yield		0	%		0	%
Expected term (in years)		5.50 - 6.08			5.27 – 6.08
Expected volatility		81.69 - 87.32	%		80.75 – 87.64	%

As of September 30, 2023, the Company had unrecognized stock-based compensation expense of $14.3 million related to stock options issued to employees and directors, which is expected to be recognized over a weighted-average period of 2.3 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, 2022	46,160	$	5.51
Vested	(31,793)	$	5.51
Canceled/Forfeited	(1,293)	$	5.51
Unvested as of September 30, 2023	13,074	$	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. The aggregate fair value of the restricted stock awards that vested during the nine months ended September 30, 2023 and 2022 was $0.1 million and $0.3 million, respectively. As of September 30, 2023, total unrecognized stock-based compensation expense related to unvested restricted stock awards was $0.1 million, which is expected to be recognized over a weighted-average period of 0.4 years.

Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2023

Summary of Significant Accounting Policies

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Basis of Presentation

The Company’s unaudited interim condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative U.S. GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASUs”) of the Financial Accounting Standards Board (“FASB”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been

condensed or omitted from this report, as is permitted by such rules and regulations. Accordingly, these unaudited interim condensed consolidated financial statements should be read in conjunction with the audited financial statements as of and for the year ended December 31, 2022 and notes thereto, included in the Company’s Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission (“SEC”) on March 2, 2023. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited financial statements. In the opinion of the Company’s management, the unaudited interim condensed consolidated financial statements contain all adjustments which are necessary to present fairly the Company’s financial position as of September 30, 2023 and the results of its operations for the three and nine months ended September 30, 2023 and 2022 and cash flows for the nine months ended September 30, 2023 and 2022. Such adjustments are of a normal and recurring nature. The results for the three and nine months ended September 30, 2023 are not necessarily indicative of the results for the year ending December 31, 2023 or for any future period.

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 security 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, 2022. 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, 2022, except as noted below.

Collaboration Agreements

The Company analyzes its collaboration agreements to assess whether such arrangements involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards dependent on the commercial success of such activities and therefore within the scope of ASC Topic 808, Collaborative Arrangements (“ASC 808”). For arrangements within the scope of ASC 808 that contain multiple elements, the Company first determines which elements of the collaboration are deemed to be within the scope of ASC 808 and which elements of the collaboration are more reflective of a vendor-customer relationship and therefore within the scope of ASC Topic 606, Revenue from Contracts with Customers (“ASC 606”). For elements of collaboration arrangements that are accounted for pursuant to ASC 808, an appropriate recognition method is determined and applied consistently, either by analogy to authoritative accounting literature or by applying a reasonable and rational policy election. For collaboration agreements where the Company is reimbursed for a portion of its research and development expenses or participates in the cost-sharing of such research and development expenses, such reimbursements and cost-sharing arrangements are reflected as a reduction of research and development expenses in the Company’s condensed consolidated statements of operations and comprehensive loss, as the Company does not consider performing research and development services for reimbursement to be a part of its ongoing major or central operations.

Concentrations of Credit Risk

Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash and cash equivalents. The Company holds all cash and cash equivalents at accredited financial institutions. Bank accounts in the United States are generally insured by the Federal Deposit Insurance Corporation (“FDIC”) up to $250,000. Substantially all of the Company’s cash and cash equivalents are FDIC insured, including funds held through an insured cash sweep program. The Company has not experienced any losses in its cash and cash equivalents and does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships.

Net Loss Per Share (Details) - shares	9 Months Ended
Net Loss Per Share (Details) - shares	Sep. 30, 2023	Sep. 30, 2022
Net Loss Per Share
Total common stock equivalents	7,899,671	5,066,345
Restricted stock
Net Loss Per Share
Total common stock equivalents	13,074	64,458
Stock options
Net Loss Per Share
Total common stock equivalents	7,823,478	4,999,256
Warrants
Net Loss Per Share
Total common stock equivalents	2,631	2,631
Employee stock purchase plan
Net Loss Per Share
Total common stock equivalents	60,488

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current assets
Cash and cash equivalents	$ 59,772	$ 120,385
Prepaid expenses and other current assets	4,708	4,111
Total current assets	64,480	124,496
Restricted cash	1,580	1,562
Property and equipment, net	6,366	7,255
Operating lease right-of-use asset	5,247	5,585
Other non-current assets	169	267
Total assets	77,842	139,165
Current liabilities
Accounts payable	1,486	3,125
Accrued expenses	9,404	10,327
Operating lease liability, current portion	1,014	918
Note payable, current portion	4,957	6,667
Other current liabilities	68	82
Total current liabilities	16,929	21,119
Note payable, net of current portion		3,165
Operating lease liability, net of current portion	8,415	9,189
Other non-current liabilities		45
Total liabilities	25,344	33,518
Commitments and contingencies (Note 7)
Stockholders' equity
Preferred stock, $0.0001 par value; 5,000,000 shares authorized, no shares issued or outstanding
Common stock, $0.0001 par value; 200,000,000 shares authorized at September 30, 2023 and December 31, 2022; 27,542,000 shares issued and 27,528,926 shares outstanding at September 30, 2023; 27,471,607 shares issued and 27,425,447 shares outstanding at December 31, 2022	3	3
Additional paid-in capital	360,352	354,752
Accumulated deficit	(307,857)	(249,108)
Total stockholders' equity	52,498	105,647
Total liabilities and stockholders' equity	$ 77,842	$ 139,165

Preferred Stock and Common Stock (Tables)

9 Months Ended

Sep. 30, 2023

Preferred Stock and Common Stock

Schedule of Shares Reserved for Future Issuance


	September 30,	December 31,
	2023	2022
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 2020 Plan, 2021 Plan and 2022 Inducement Plan	7,823,478	4,960,553
Shares of common stock reserved for future awards under the 2021 Plan	1,412,759	2,848,568
Shares of common stock reserved for future awards under the 2022 Inducement Plan	220,000	275,000
Shares of common stock reserved for purchase under the 2021 ESPP	772,507	566,720
Total shares reserved for future issuance	10,231,375	8,653,472

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Total
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
Vesting of restricted common stock (in shares)	15,441
Exercise of stock options		16		16
Exercise of stock options (in shares)	2,657
Stock-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
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
Stock-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
Stock-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
Beginning balance at Dec. 31, 2022	$ 3	354,752	(249,108)	105,647
Beginning balance (in shares) at Dec. 31, 2022	27,425,447
Stockholders' Deficit
Vesting of restricted common stock (in shares)	14,217
Exercise of stock options (in shares)	156
Stock-based compensation expense		1,791		1,791
Net loss			(22,646)	(22,646)
Ending balance at Mar. 31, 2023	$ 3	356,543	(271,754)	84,792
Ending balance (in shares) at Mar. 31, 2023	27,439,820
Beginning balance at Dec. 31, 2022	$ 3	354,752	(249,108)	$ 105,647
Beginning balance (in shares) at Dec. 31, 2022	27,425,447
Stockholders' Deficit
Exercise of stock options (in shares)				2,757
Net loss				$ (58,749)
Ending balance at Sep. 30, 2023	$ 3	360,352	(307,857)	52,498
Ending balance (in shares) at Sep. 30, 2023	27,528,926
Beginning balance at Mar. 31, 2023	$ 3	356,543	(271,754)	84,792
Beginning balance (in shares) at Mar. 31, 2023	27,439,820
Stockholders' Deficit
Issuance of common stock under employee stock purchase plan		140		140
Issuance of common stock under employee stock purchase plan (in shares)	68,929
Vesting of restricted common stock (in shares)	9,978
Exercise of stock options (in shares)	168
Stock-based compensation expense		1,800		1,800
Net loss			(19,355)	(19,355)
Ending balance at Jun. 30, 2023	$ 3	358,483	(291,109)	67,377
Ending balance (in shares) at Jun. 30, 2023	27,518,895
Stockholders' Deficit
Vesting of restricted common stock (in shares)	7,598
Exercise of stock options		8		8
Exercise of stock options (in shares)	2,433
Stock-based compensation expense		1,861		1,861
Net loss			(16,748)	(16,748)
Ending balance at Sep. 30, 2023	$ 3	$ 360,352	$ (307,857)	$ 52,498
Ending balance (in shares) at Sep. 30, 2023	27,528,926

Loan and Security Agreement (Tables)

9 Months Ended

Sep. 30, 2023

Loan and Security Agreement

Schedule of minimum aggregate future loan principal payments


	Minimum Loan
	Payments
2023 (remaining three months)	$	1,667
2024		3,333
Total future principal payments		5,000
Less: unamortized discount		(43)
Total note payable	$	4,957

Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2023

Stock-Based Compensation

Schedule of stock-based compensation expense


	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
Research and development expense	$	548	$	594	$	1,670	$	1,827
General and administrative expense		1,313		1,277		3,782		4,782
Total stock-based compensation expense	$	1,861	$	1,871	$	5,452	$	6,609

Summary of stock option activity


				Weighted
				Average
				Remaining	Aggregate
		Weighted		Contractual	Intrinsic
	Number of	Average		Term	Value (1)
	Stock Options	Exercise Price		(In years)	(In thousands)
Outstanding as of December 31, 2022	4,960,553	$	8.04	8.59	$	89
Granted	3,738,555	$	2.75
Exercised	(2,757)	$	2.82
Cancelled/forfeited	(872,873)	$	6.77
Outstanding as of September 30, 2023	7,823,478	$	5.66	8.54	$	-
Exercisable as of September 30, 2023	2,768,685	$	7.19	7.66	$	-

Schedule of assumptions used in determining fair value of options granted


	Nine Months Ended September 30,
	2023			2022
Risk-free interest rate		3.57 - 4.40	%		1.47 – 3.63	%
Expected dividend yield		0	%		0	%
Expected term (in years)		5.50 - 6.08			5.27 – 6.08
Expected volatility		81.69 - 87.32	%		80.75 – 87.64	%

Summary of restricted stock activity


	Number	Weighted
	of Shares	Average
	of Restricted	Grant Date
	Stock	Fair Value
Unvested as of December 31, 2022	46,160	$	5.51
Vested	(31,793)	$	5.51
Canceled/Forfeited	(1,293)	$	5.51
Unvested as of September 30, 2023	13,074	$	5.51

Collaboration Agreements (Details) - Clinical Supply Agreement - F. Hoffmann-La Roche Ltd. $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2023 USD ($)	Sep. 30, 2023 USD ($)
Prepaid expenses and other current assets
Collaboration Agreements
Earned but unpaid cost-sharing payments	$ 2.0	$ 2.0
Research and development
Collaboration Agreements
Reduction in research and development expenses	$ 2.0	$ 2.0

Property and Equipment, Net (Tables)

9 Months Ended

Sep. 30, 2023

Property and Equipment, Net

Summary of property and equipment, net


	September 30,		December 31,
	2023		2022
Laboratory equipment	$	6,091	$	5,587
Computers and software		183		228
Furniture and fixtures		681		636
Leasehold improvements		5,124		5,124
Construction in process		—		98
Total property and equipment		12,079		11,673
Less: accumulated depreciation		(5,713)		(4,418)
Property and equipment, net	$	6,366	$	7,255

Loan and Security Agreement - Description (Details) - Loan Agreement - USD ($) $ in Millions	1 Months Ended
	Nov. 30, 2019	Sep. 30, 2023
Loan and security agreement
Borrowed amount	$ 10.0
Interest rate at end of period (as a percent)		8.75%
Additional interest rate upon event of default (as a percent)	5.00%
Minimum
Loan and security agreement
Stated interest rate	4.75%
Prime rate
Loan and security agreement
Basis spread (as percent)	0.25%

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details

Loan and Security Agreement - Maturities (Details) - Loan Agreement - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Minimum aggregate future loan payments
2023 (remaining three months)	$ 1,667
2024	3,333
Total future principal payments	5,000
Less: unamortized discount	(43)
Total notes payable	4,957
Interest expense	$ 600	$ 500

- Definition

Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

+ References + Details

Stock-Based Compensation - Stock-based compensation expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Stock-Based Compensation
Total compensation expense	$ 1,861	$ 1,871	$ 5,452	$ 6,609
Research and development expense
Stock-Based Compensation
Total compensation expense	548	594	1,670	1,827
General and administrative expense
Stock-Based Compensation
Total compensation expense	$ 1,313	$ 1,277	$ 3,782	$ 4,782

Description of Business and Liquidity and Going Concern - Liquidity and Going Concern (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Description of Business and Liquidity and Going Concern
Accumulated deficit	$ 307,857						$ 307,857		$ 249,108
Net loss	16,748	$ 19,355	$ 22,646	$ 19,790	$ 24,613	$ 21,353	58,749	$ 65,756
Cash and cash equivalents	$ 59,772			$ 139,143			$ 59,772	$ 139,143	$ 120,385
Substantial doubt about going concern within one year							true

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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+ Details

- Definition

Amount of accumulated undistributed earnings (deficit).

+ References + Details

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Operating expenses
Research and development	$ 11,051	$ 13,038	$ 40,400	$ 44,204
General and administrative	6,310	7,168	20,603	21,778
Total operating expenses	17,361	20,206	61,003	65,982
Loss from operations	(17,361)	(20,206)	(61,003)	(65,982)
Other income, net
Other income, net	613	416	2,254	226
Total other income, net	613	416	2,254	226
Net loss	(16,748)	(19,790)	(58,749)	(65,756)
Comprehensive loss	$ (16,748)	$ (19,790)	$ (58,749)	$ (65,756)
Net loss per share, basic (in dollars per share)	$ (0.61)	$ (0.72)	$ (2.14)	$ (2.40)
Net loss per share, diluted (in dollars per share)	$ (0.61)	$ (0.72)	$ (2.14)	$ (2.40)
Weighted average common shares outstanding, basic (in shares)	27,523,821	27,399,906	27,475,579	27,384,085
Weighted average common shares outstanding, diluted (in shares)	27,523,821	27,399,906	27,475,579	27,384,085

Preferred Stock and Common Stock

9 Months Ended

Sep. 30, 2023

Preferred Stock and Common Stock

Preferred Stock and Common Stock

8. Preferred Stock and Common Stock

Undesignated Preferred Stock

As of September 30, 2023 and December 31, 2022, 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. As of September 30, 2023 and December 31, 2022, there were no shares of preferred stock issued or outstanding.

Common Stock

As of September 30, 2023 and December 31, 2022, the Company is authorized to issue up to 200,000,000 shares of common stock, $0.0001 par value per share under its certificate of incorporation, as amended.

Shares Reserved for Future Issuance

As of September 30, 2023 and December 31, 2022, the Company had reserved shares of common stock for future issuance under the 2020 Stock Incentive Plan (as amended, the “2020 Plan”), the 2021 Stock Incentive Plan (the “2021 Plan”), the 2022 Inducement Stock Incentive Plan (the “2022 Inducement Plan”) and the 2021 Employee Stock Purchase Plan (the “2021 ESPP”) as follows:


	September 30,	December 31,
	2023	2022
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 2020 Plan, 2021 Plan and 2022 Inducement Plan	7,823,478	4,960,553
Shares of common stock reserved for future awards under the 2021 Plan	1,412,759	2,848,568
Shares of common stock reserved for future awards under the 2022 Inducement Plan	220,000	275,000
Shares of common stock reserved for purchase under the 2021 ESPP	772,507	566,720
Total shares reserved for future issuance	10,231,375	8,653,472

Stock-Based Compensation - Employee Stock Purchase Plan (Details) - shares		1 Months Ended	9 Months Ended
	Jan. 01, 2023	Oct. 31, 2021	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Stock-Based Compensation
Common stock reserved for issuance (in shares)			10,231,375		8,653,472
2021 ESPP
Stock-Based Compensation
Common stock reserved for issuance (in shares)		292,031	772,507		566,720
Additional common stock reserved under the plan (in shares)	274,716
Shares issued under plan (in shares)			68,929	0
Shares available for future issuance (in shares)			772,507
2021 ESPP \| Maximum
Stock-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)		1.00%

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details