0000950170-23-053302 | 10-Q | XBRL Viewer

Accrued Expenses and Other Current Liabilities (Tables)

9 Months Ended

Sep. 30, 2023

Summary of Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following:


	September 30, 2023		December 31, 2022
External research and development services	$	20	$	533
Payroll and payroll-related costs		103		425
Professional fees		995		492
Restructuring and other costs (Note 8)		12		—
Other		10		181
	$	1,140	$	1,631

Condensed Statements of Operations and Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Statement [Abstract]
Unrealized gain (loss) on investments, net of tax	$ 0	$ 0	$ 0	$ 0

Common Stock - Additional Information (Detail)				1 Months Ended	3 Months Ended	9 Months Ended	12 Months Ended
Common Stock - Additional Information (Detail)	Nov. 10, 2022 shares	Jan. 29, 2021 USD ($)	Apr. 02, 2019 $ / shares shares	Jul. 31, 2019 shares	Mar. 31, 2022 shares	Sep. 30, 2023 USD ($) $ / shares shares	Dec. 31, 2022 $ / shares shares	Dec. 31, 2021 USD ($) shares	Dec. 31, 2020 USD ($) $ / shares shares	Nov. 09, 2022 shares	Jun. 21, 2022 USD ($)	Jun. 16, 2021 $ / shares shares
Class of Stock [Line Items]
Common stock, shares authorized	15,000,000					45,000,000	45,000,000		7,500,000	300,000,000		15,000,000
Common stock, par value \| $ / shares						$ 0.001	$ 0.001		$ 0.001			$ 0.001
Common stock, dividends declared \| $ / shares						$ 0	0
Reverse stock split conversion ratio	0.05
Maximum floor price per share \| $ / shares							$ 6
Common and Pre-funded Warrants [Member]
Class of Stock [Line Items]
Aggregate number of common stock shares issued and sold			54,837
Pre-funded Warrants [Member]
Class of Stock [Line Items]
Aggregate number of common stock shares issued and sold			54,837
Warrants outstanding exercised				54,837
Warrants exercise price \| $ / shares			$ 0.2
Common Stock [Member]
Class of Stock [Line Items]
Gross proceeds from common stock shares issued and sold \| $						$ 145,467,000
Stock issued during period, shares					12,500
Common Warrants [Member]
Class of Stock [Line Items]
Aggregate number of common stock shares issued and sold			54,837
Warrants outstanding						646,759
Warrants exercise price \| $ / shares						$ 40
Common Warrants [Member] \| Common and Pre-funded Warrants [Member]
Class of Stock [Line Items]
Purchase price per share \| $ / shares			$ 40.2
Private Placement [Member]
Class of Stock [Line Items]
Aggregate number of common stock shares issued and sold			591,922
Private Placement [Member] \| Common Stock [Member]
Class of Stock [Line Items]
Aggregate number of common stock shares issued and sold			591,922
Private Placement [Member] \| Common Warrants [Member]
Class of Stock [Line Items]
Aggregate number of common stock shares issued and sold			591,922
Purchase price per share \| $ / shares			$ 40.2
ATM Sales Agreement [Member]
Class of Stock [Line Items]
Aggregate number of common stock shares issued and sold						0	0	261,270
Expenses fees payable \| $								$ 329,000
Gross proceeds from common stock shares issued and sold \| $								$ 10,922,000
ATM Sales Agreement [Member] \| Jones Trading Institutional Services LLC and William Blair & Company, LLC [Member] \| Maximum [Member]
Class of Stock [Line Items]
Common stock offering price \| $											$ 14,024,000
Stock issued during period, value \| $		$ 30,000,000
Purchase Agreement [Member] \| Linco Ln Park Capital L L C [Member]
Class of Stock [Line Items]
Aggregate number of common stock shares issued and sold						0	0	68,750	29,411
Gross proceeds from common stock shares issued and sold \| $								$ 2,614,000	$ 500,000

Condensed Statement of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Gain (Loss) [Member]	Accumulated Deficit [Member]
Beginning balance at Dec. 31, 2021	$ 43,904	$ 91	$ 289,282	$ (13)	$ (245,456)
Beginning balance, shares at Dec. 31, 2021		4,528,667
Issuance of common stock, shares		12,500
Stock-based compensation expense	689		689
Unrealized gain (loss) on investments	(62)			(62)
Net loss	(8,422)				(8,422)
Ending balance at Mar. 31, 2022	36,109	$ 91	289,971	(75)	(253,878)
Ending balance, shares at Mar. 31, 2022		4,541,167
Beginning balance at Dec. 31, 2021	43,904	$ 91	289,282	(13)	(245,456)
Beginning balance, shares at Dec. 31, 2021		4,528,667
Unrealized gain (loss) on investments	(85)
Net loss	(22,782)
Ending balance at Sep. 30, 2022	22,696	$ 91	290,941	(98)	(268,238)
Ending balance, shares at Sep. 30, 2022		4,541,167
Beginning balance at Mar. 31, 2022	36,109	$ 91	289,971	(75)	(253,878)
Beginning balance, shares at Mar. 31, 2022		4,541,167
Stock-based compensation expense	528		528
Unrealized gain (loss) on investments	(26)			(26)
Net loss	(7,992)				(7,992)
Ending balance at Jun. 30, 2022	28,619	$ 91	290,499	(101)	(261,870)
Ending balance, shares at Jun. 30, 2022		4,541,167
Stock-based compensation expense	442		442
Unrealized gain (loss) on investments	3			3
Net loss	(6,368)				(6,368)
Ending balance at Sep. 30, 2022	22,696	$ 91	290,941	(98)	(268,238)
Ending balance, shares at Sep. 30, 2022		4,541,167
Beginning balance at Dec. 31, 2022	$ 18,623	$ 91	291,365	(48)	(272,785)
Beginning balance, shares at Dec. 31, 2022	4,541,167	4,541,167
Stock-based compensation expense	$ 391		391
Unrealized gain (loss) on investments	38			38
Net loss	(4,779)				(4,779)
Ending balance at Mar. 31, 2023	14,273	$ 91	291,756	(10)	(277,564)
Ending balance, shares at Mar. 31, 2023		4,541,167
Beginning balance at Dec. 31, 2022	$ 18,623	$ 91	291,365	(48)	(272,785)
Beginning balance, shares at Dec. 31, 2022	4,541,167	4,541,167
Unrealized gain (loss) on investments	$ 48
Net loss	(8,393)
Ending balance at Sep. 30, 2023	$ 11,198	$ 91	292,285		(281,178)
Ending balance, shares at Sep. 30, 2023	4,541,167	4,541,167
Beginning balance at Mar. 31, 2023	$ 14,273	$ 91	291,756	(10)	(277,564)
Beginning balance, shares at Mar. 31, 2023		4,541,167
Stock-based compensation expense	300		300
Unrealized gain (loss) on investments	8			8
Net loss	(1,787)				(1,787)
Ending balance at Jun. 30, 2023	12,794	$ 91	292,056	(2)	(279,351)
Ending balance, shares at Jun. 30, 2023		4,541,167
Stock-based compensation expense	229		229
Unrealized gain (loss) on investments	2			$ 2
Net loss	(1,827)				(1,827)
Ending balance at Sep. 30, 2023	$ 11,198	$ 91	$ 292,285		$ (281,178)
Ending balance, shares at Sep. 30, 2023	4,541,167	4,541,167

- Definition

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

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Amount of equity (deficit) attributable to parent. Excludes temporary equity and equity attributable to noncontrolling interest.

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+ Details

Condensed 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
Income Statement [Abstract]
Revenue	$ 0	$ 0	$ 0	$ 0
Operating expenses:
Research and development	22	4,239	2,019	15,565
General and administrative	1,955	2,243	6,027	7,379
Restructuring and Other	6		940
Total operating expenses	1,983	6,482	8,986	22,944
Loss from operations	(1,983)	(6,482)	(8,986)	(22,944)
Interest income	155	110	322	180
Other income (expense), net	1	4	271	(18)
Net loss	$ (1,827)	$ (6,368)	$ (8,393)	$ (22,782)
Net loss per share - basic	$ (0.4)	$ (1.4)	$ (1.85)	$ (5.02)
Net loss per share - diluted	$ (0.4)	$ (1.4)	$ (1.85)	$ (5.02)
Weighted average common shares outstanding - basic	4,541,167	4,541,179	4,541,167	4,538,707
Weighted average common shares outstanding - diluted	4,541,167	4,541,179	4,541,167	4,538,707
Comprehensive loss:
Net loss	$ (1,827)	$ (6,368)	$ (8,393)	$ (22,782)
Other comprehensive loss:
Unrealized gain (loss) on investments, net of tax of $0	2	3	48	(85)
Total other comprehensive gain (loss)	2	3	48	(85)
Total comprehensive loss	$ (1,825)	$ (6,365)	$ (8,345)	$ (22,867)

Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
Statements of Cash Flows - USD ($) $ in Thousands	Sep. 30, 2023	Sep. 30, 2022
Cash flows from operating activities:
Net loss	$ (8,393)	$ (22,782)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	67	126
Net amortization of premiums and discounts on investments	(156)	(85)
Stock-based compensation expense	920	1,659
Gain on sale of property and equipment	(42)
Loss on disposal of fixed assets	16
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(93)	667
Other assets	24
Accounts payable	(1,236)	(265)
Operating lease liabilities	(33)	(95)
Accrued expenses and other current liabilities	(491)	319
Net cash used in operating activities	(9,417)	(20,456)
Cash flows from investing activities:
Proceeds from sale of property and equipment	42
Purchases of investments		(19,912)
Proceeds from sales or maturities of investments	16,250	41,607
Net cash provided by investing activities	16,292	21,695
Cash flows from financing activities:
Net increase in cash, cash equivalents and restricted cash	6,875	1,239
Cash, cash equivalents and restricted cash at beginning of period	5,219	3,625
Cash, cash equivalents and restricted cash at end of period	$ 12,094	$ 4,864

Common Stock

9 Months Ended

Sep. 30, 2023

Equity [Abstract]

Common Stock

9. Common Stock

On June 16, 2021, the Company filed a certificate of amendment to its restated certificate of incorporation which increased the authorized number of shares of common stock from 7,500,000 shares of $0.001 par value common stock to 15,000,000 shares of common stock.

Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders. Common stockholders are entitled to receive dividends, as may be declared by the Company’s board of directors, if any, subject to the preferential dividend rights of the preferred stock. As of September 30, 2023 and December 31, 2022, no dividends had been declared.

Reverse Stock Split

The Company’s stockholders approved a reverse stock split of the Company’s common stock on June 15, 2022. The Company effected the Reverse Stock Split on November 10, 2022. Pursuant to the Reverse Stock Split, every 20 shares of the Company's issued and outstanding shares of common stock were automatically combined into one issued and outstanding share of common stock, without any change in the par value per share of the common stock. The Reverse Stock Split reduced the authorized number of shares of common stock from 300,000,000 to 15,000,000 and, pursuant to the certificate of amendment, such reduced authorized number of shares of common stock was subsequently multiplied by three, such that following the Reverse Stock Split the Company has 45,000,000 shares of common stock authorized. The Reverse Stock Split affected all issued and outstanding shares of the Company's common stock, and the respective numbers of shares of common stock underlying the Company’s outstanding stock options, outstanding warrants and the Company’s equity incentive plans were proportionately adjusted. All share and per share amounts disclosed give effect to the Reverse Stock Split on a retroactive basis.

Sales of Common Stock

On January 29, 2021, the Company entered into a Capital on Demand™ Sales Agreement (the “ATM Sales Agreement”) with JonesTrading Institutional Services LLC (“JonesTrading”) and William Blair & Company, L.L.C. (“William Blair” and, collectively with JonesTrading, the “Agents”), pursuant to which the Company may offer and sell shares of its common stock having an aggregate offering price of up to $30,000 from time to time through or to the Agents (the “ATM Offering”). During the year ended December 31, 2021, the Company issued and sold an aggregate of 261,270 shares of its common stock pursuant to the ATM Sales Agreement, resulting in gross proceeds of $10,922 before deducting expenses of $329. Pursuant to a prospectus relating to the ATM Sales Agreement filed by the Company with the SEC on June 21, 2022, the Company may from time to time offer and sell shares of its common stock having an aggregate offering price of up to $14,024 under the ATM Sales Agreement. There were no sales under the ATM Sales Agreement during the nine months ended September 30, 2023, or the year ended December 31, 2022.

During the year ended December 31, 2021, the Company issued and sold an aggregate of 68,750 shares of its common stock to Lincoln Park Capital, LLC pursuant to a purchase agreement entered into between Lincoln Park Capital, LLC ("LPC") and the Company in September 2020, resulting in gross proceeds of $2,614. During the year ended December 31, 2020, the Company issued and sold 29,411 shares to LPC under the purchase agreement for proceeds of $500. There were no sales under the purchase agreement during the nine months ended September 30, 2023, or the year ended December 31, 2022. Under the purchase agreement, the

Company may not effect any sales of shares of common stock on any purchase date that the closing sale price of its common stock on Nasdaq is less than the floor price of $6.00 per share, which will be adjusted for any reorganization, recapitalization, non-cash dividend, stock split or other similar transaction.

On April 2, 2019, the Company issued and sold in a private placement an aggregate of (i) 591,922 units, consisting of 591,922 shares of its common stock and associated warrants, or the common warrants, to purchase an aggregate of 591,922 shares of common stock, for a combined price of $40.20 per unit and (ii) 54,837 units, consisting of (a) pre-funded warrants to purchase 54,837 shares of our common stock and (b) associated common warrants to purchase 54,837 shares of common stock, for a combined price of $40.20 per unit. The pre-funded warrants had an exercise price of $0.20 per share and had no expiration. In July 2019, all outstanding pre-funded warrants were exercised for 54,837 shares of common stock. At September 30, 2023, there were 646,759 common warrants outstanding with an exercise price of $40.00 per share.

The Company has assessed the warrants for appropriate equity or liability classification and determined the warrants are freestanding instruments that do not meet the definition of a liability pursuant to ASC 480 and do not meet the definition of a derivative pursuant to ASC 815. The warrants are indexed to the Company’s common stock and meet all other conditions for equity classification under ASC 480 and ASC 815. Accordingly, the warrants are classified as equity and accounted for as a component of additional paid-in capital at the time of issuance.

- Definition

The entire disclosure for equity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
-Paragraph 13
-Subparagraph (b)
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 1
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
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Reference 19: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Property and Equipment, Net

9 Months Ended

Sep. 30, 2023

Property, Plant and Equipment [Abstract]

Property and Equipment, Net

5. Property and Equipment, Net

Property and equipment, net consisted of the following:


	September 30, 2023			December 31, 2022
Computer equipment and software	$	324		$	340
Less: Accumulated depreciation and amortization		(295	)		(270	)
	$	29		$	70

Depreciation and amortization expense for the nine months ended September 30, 2023 and 2022 was $37 and $44 respectively. During the nine months ended September 30, 2023, assets with a cost of $16 and accumulated depreciation of $10 were disposed of for no proceeds, resulting in a loss on disposal of $6. During the nine months ended September 30, 2023, the Company sold fully depreciated assets, resulting in a gain on sale of $42.

Investments - Summary of Fair Value of Available for Sale Investments (Detail) $ in Thousands	Dec. 31, 2022 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Investments, Amortized Cost	$ 16,096
Investments, Gross Unrealized Loss	(48)
Investments, Fair Value	16,048
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments, Amortized Cost	12,846
Investments, Gross Unrealized Loss	(32)
Investments, Fair Value	12,814
Treasury Bills [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments, Amortized Cost	3,250
Investments, Gross Unrealized Loss	(16)
Investments, Fair Value	$ 3,234

- 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
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+ Details

Commitments and Contingencies - Additional Information (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) Milestone	Sep. 30, 2022 USD ($)	Feb. 28, 2010 USD ($)	Dec. 31, 2006 USD ($)
Harvard and Dana-Farber Agreement [Member]
Other Commitments [Line Items]
Milestone payments	$ 0	$ 0	$ 0	$ 0
Additional milestones achieved \| Milestone			0
Additional liabilities for milestone payments	0		$ 0
Payments for royalties			0
Harvard and Dana-Farber Agreement [Member] \| Therapeutic Product [Member]
Other Commitments [Line Items]
Aggregate milestones payments					$ 7,700,000
Harvard and Dana-Farber Agreement [Member] \| Diagnostic Product [Member]
Other Commitments [Line Items]
Aggregate milestones payments					$ 700,000
Harvard and Dana-Farber Agreement [Member] \| License [Member]
Other Commitments [Line Items]
Annual license maintenance fees			35,000	110,000
Harvard and Dana-Farber Agreement [Member] \| License and Maintenance [Member]
Other Commitments [Line Items]
Annual license maintenance fees	110,000
Harvard and Dana-Farber Agreement [Member] \| License and Maintenance [Member] \| Modified Scope of Agreement [Member]
Other Commitments [Line Items]
Annual license maintenance fees	35,000
Umicore Agreement [Member]
Other Commitments [Line Items]
Aggregate milestones payments						$ 6,400,000
Milestone payments	0	$ 0	$ 0	0
Additional milestones achieved \| Milestone			0
Additional liabilities for milestone payments	$ 0		$ 0
Umicore Agreement [Member] \| License [Member]
Other Commitments [Line Items]
Annual license maintenance fees			50,000	$ 50,000
Umicore Agreement [Member] \| License and Maintenance [Member]
Other Commitments [Line Items]
Annual license maintenance fees			$ 50,000

Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2023	Oct. 11, 2023
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Trading Symbol	ALRN
Entity Registrant Name	Aileron Therapeutics, Inc.
Entity Central Index Key	0001420565
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		4,541,167
Entity File Number	001-38130
Entity Tax Identification Number	13-4196017
Entity Address, Address Line One	738 Main Street
Entity Address, Address Line Two	#398
Entity Address, City or Town	Waltham
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02451
City Area Code	617
Local Phone Number	995-0900
Entity Shell Company	false
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Document Quarterly Report	true
Document Transition Report	false
Entity Incorporation, State or Country Code	DE
Title of 12(b) Security	Common Stock, $0.001 par value per share
Security Exchange Name	NASDAQ

Property and Equipment, Net - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Depreciation and amortization expense	$ 37	$ 44
Property and equipment, net	29		$ 70
Accumulated depreciation	295		$ 270
Assets Disposed of by Sale [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, net	16
Accumulated depreciation	10
Gain (loss) on sale of property and equipment	(6)
Fully Depreciated Assets [Member]
Property, Plant and Equipment [Line Items]
Gain (loss) on sale of property and equipment	$ 42

Stock-Based Awards - Summary of Stock Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 229	$ 442	$ 920	$ 1,659
Research and Development [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	37	144	227	465
General and Administrative [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 192	$ 298	$ 693	$ 1,194

- 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 22: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Stock-Based Awards - Valuation Assumptions of Stock Options Granted (Detail)	9 Months Ended
	Sep. 30, 2023
Share-Based Payment Arrangement [Abstract]
Risk-free interest rate	2.46%
Expected term (in years)	5 years 10 months 24 days
Expected volatility	94.20%
Expected dividend yield	0.00%

Investments (Tables)

9 Months Ended

Sep. 30, 2023

Investments, Debt and Equity Securities [Abstract]

Summary of Fair Value of Available for Sale Investments

The Company had no investments as of September 30, 2023. As of December 31, 2022, the fair value of available-for-sale investments by type of security was as follows:


	December 31, 2022
	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss			Fair Value
Investments:
Commercial paper	$	12,846	$	—	$	(32	)	$	12,814
Treasury bills		3,250		—		(16	)		3,234
	$	16,096	$	—	$	(48	)	$	16,048

- Definition

Tabular disclosure of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-9

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
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-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
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-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
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-Section 50
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-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
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-Publisher FASB
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Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef
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-Section 50
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-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
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-Name Accounting Standards Codification
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Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
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-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
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-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

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Reference 12: http://www.xbrl.org/2009/role/commonPracticeRef
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-Section 50
-Paragraph 3
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

+ Details

Stock-Based Awards (Tables)

9 Months Ended

Sep. 30, 2023

Share-Based Payment Arrangement [Abstract]

Valuation Assumptions of Stock Options Granted

The assumptions that the Company used to determine the grant-date fair value of the stock options granted to employees and directors during the nine months ended September 30, 2022 were as follows, presented on a weighted average basis :


	Nine Months Ended September 30, 2022
Risk-free interest rate		2.46	%
Expected term (in years)		5.9
Expected volatility		94.2	%
Expected dividend yield		0	%

Summary of Stock Option Activity

The following table summarizes the Company’s stock option activity since January 1, 2023:


	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
						(in years)
Outstanding at December 31, 2022		537,112		$	29.77		7.9	$	—
Granted		—
Exercised		—
Canceled, forfeited or expired		(68,495	)
Outstanding at September 30, 2023		468,617		$	31.76		6.4	$	—
Options exercisable at September 30, 2023		354,371		$	35.80		5.9	$	—
Options vested and expected to vest at September 30, 2023		465,772		$	31.84		6.4	$	—
Options exercisable at December 31, 2022		288,821		$	40.15		7.1	$	—
Options vested and expected to vest at December 31, 2022		529,549		$	29.95		7.8	$	—

Summary of Stock Based Compensation Expense

The Company recorded stock-based compensation expense related to stock options and restricted stock units in the following expense categories of its statements of operations and comprehensive loss:


	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
Research and development expenses	$	37	$	144	$	227	$	465
General and administrative expenses		192		298		693		1,194
	$	229	$	442	$	920	$	1,659

Nature of the Business and Basis of Presentation

9 Months Ended

Sep. 30, 2023

Accounting Policies [Abstract]

Nature of the Business and Basis of Presentation

1. Nature of the Business and Basis of Presentation

Aileron Therapeutics, Inc. (“Aileron” or the “Company”) is a clinical stage chemoprotection oncology company. The Company's product candidate, ALRN-6924, is a MDM2/MDMX dual inhibitor that leverages its proprietary peptide drug technology.

On February 21, 2023, the Company decided to terminate its Phase 1b chemoprotection trial of ALRN-6924 in patients with p53-mutated breast cancer and further development of ALRN-6924. The Company determined to reduce the Company’s remaining workforce from nine to three full-time employees. The Company also announced that it is exploring a range of strategic alternatives to maximize stockholder value. The Company has engaged a third party to act as a strategic advisor for this process. Strategic alternatives that are being evaluated may include, but are not limited to, an acquisition, a merger, a business combination, a sale of assets or other transaction. There is no set timetable for this process and there can be no assurance that this process will result in the Company pursuing a transaction or that any transaction, if pursued, will be completed.

When used as a chemoprotective agent, ALRN-6924 is designed to activate p53, which in turn upregulates p21, a known inhibitor of the cell replication cycle. ALRN-6924 was the only reported chemoprotective agent in clinical development to employ a biomarker strategy, in which the Company exclusively focused on treating patients with p53-mutated cancers. The Company originally initiated development of ALRN-6924 as an anti-cancer agent to restore p53-dependent tumor suppression in p53 wild-type tumors. When used as an anti-cancer agent, ALRN-6924 is designed to disrupt the interaction of p53 suppressors MDM2 and MDMX with tumor suppressor p53 to reactivate tumor suppression in non-mutant, or wild-type, p53 cancers.

The Company is subject to risks common to companies in the biotechnology industry, including but not limited to, new technological innovations, protection of proprietary technology, dependence on key personnel, compliance with government regulations, uncertainties in the clinical development of product candidates and in the ability to obtain needed additional financing. ALRN-6924 will require significant additional research and development efforts, including preclinical and clinical testing and regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel infrastructure and extensive compliance-reporting capabilities.

On November 10, 2022, the Company effected a one-for-twenty reverse stock split on its common stock (the “Reverse Stock Split”). The Reverse Stock Split was reflected on the Nasdaq Capital Market beginning with the opening of trading on November 11, 2022. Pursuant to the Reverse Stock Split, every 20 shares of the Company's issued and outstanding shares of common stock were automatically combined into one issued and outstanding share of common stock, without any change in the par value per share of the common stock. The Reverse Stock Split reduced the authorized number of shares of common stock from 300,000,000 to 15,000,000 and, pursuant to the certificate of amendment, such reduced authorized number of shares of common stock was subsequently multiplied by three, such that following the Reverse Stock Split the Company has 45,000,000 shares of common stock authorized. The Reverse Stock Split affected all issued and outstanding shares of the Company's common stock, and the respective numbers of shares of common stock underlying the Company’s outstanding stock options, outstanding warrants and the Company's equity incentive plans were proportionately adjusted. All share and per share amounts of the common stock included in the accompanying financial statements have been retrospectively adjusted to give effect to the Reverse Stock Split for all periods presented.

The accompanying financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”).

Liquidity

In accordance with Accounting Standards Update (“ASU”) No. 2014-15, Disclosures of Uncertainties about an Entity’s Ability to Continue as a Going Concern (Subtopic 205-40), management must evaluate whether there are conditions or events, considered in the aggregate, that raise substantial doubt about the company’s ability to continue as a going concern within one year after the date that the financial statements are issued. This evaluation initially does not take into consideration the potential mitigating effect of management’s plans that have not been fully implemented as of the date the financial statements are issued. When substantial doubt exists under this methodology, management evaluates whether the mitigating effect of its plans sufficiently alleviates substantial doubt about the company’s ability to continue as a going concern. The mitigating effect of management’s plans, however, is only considered if both (1) it is probable that the plans will be effectively implemented within one year after the date that the financial statements are issued, and (2) it is probable that the plans, when implemented, will mitigate the relevant conditions or events that raise substantial doubt about the entity’s ability to continue as a going concern within one year after the date that the financial statements are issued. Generally, to be considered probable of being effectively implemented, the plans must have been approved before the date that the financial statements are issued.

The Company’s interim financial statements have been prepared on a going concern basis, which contemplates the continuity of operations, realization of assets and the satisfaction of liabilities in the ordinary course of business. Through September 30, 2023, the Company has financed operations primarily through $145,467 in net proceeds from sales of common stock and warrants, $131,211 from sales of preferred stock prior to its IPO, and $34,910 from a collaboration agreement in 2010.

As of September 30, 2023, the Company had cash, and cash equivalents of $12,069. The Company has incurred losses and negative cash flows from operations and had an accumulated deficit of $281,178 as of September 30, 2023. The Company expects to continue to generate losses for the foreseeable future.

While the Company has cash, and cash equivalents of $12,069 as of September 30, 2023, due to the inherent uncertainty in the timing and cost of potential strategic alternatives, including their impact on its cash consumption, the Company has concluded that as of the date of this Quarterly Report on Form 10-Q there is substantial doubt about its ability to continue as a going concern for a period of twelve months from the issuance of these interim financial statements.

The Company would need substantial funding to support its continuing operations. There can be no assurance that a strategic transaction will be completed and the Company’s board of directors may decide to pursue a dissolution and liquidation. If the Company is unable to enter into a strategic transaction, on a timely basis or at all, the Company may consider seeking protection under the bankruptcy laws. If the Company decides to seek protection under the bankruptcy laws, the Company would expect that it would file for bankruptcy at a time that is earlier than when it would otherwise exhaust its cash resources. If the Company decides to dissolve and liquidate its assets or to seek protection under the bankruptcy laws, it is unclear to what extent the Company will be able to pay its obligations, and, it is further unclear whether and to what extent any resources will be available for distributions to its stockholders. The financial statements do not include any adjustments that might result from the outcome of this uncertainty.

Accrued Expenses and Other Current Liabilities - Summary of Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
External research and development services	$ 20	$ 533
Payroll and payroll-related costs	103	425
Professional fees	995	492
Restructuring and other costs (Note 8)	12
Other	10	181
Total accrued expenses and other current liabilities	$ 1,140	$ 1,631

Stock-Based Awards - Summary of Stock Option Activity (Detail) - $ / shares	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Share-Based Payment Arrangement [Abstract]
Number of Shares, Beginning balance	537,112
Number of Shares, Canceled, forfeited or expired	(68,495)
Number of Shares, Ending balance	468,617	537,112
Number of Shares, Options exercisable	354,371	288,821
Number of Shares, Options vested and expected to vest	465,772	529,549
Weighted Average Exercise Price, Beginning balance	$ 29.77
Weighted Average Exercise Price, Ending balance	31.76	$ 29.77
Weighted Average Exercise Price, Options exercisable	35.80	40.15
Weighted Average Exercise Price, Options vested and expected to vest	$ 31.84	$ 29.95
Weighted-Average Remaining Contractual Term, Outstanding	6 years 4 months 24 days	7 years 10 months 24 days
Weighted Average Remaining Contractual Term, Options exercisable	5 years 10 months 24 days	7 years 1 month 6 days
Weighted Average Remaining Contractual Term, Options vested and expected to vest	6 years 4 months 24 days	7 years 9 months 18 days

Property and Equipment, Net - Summary of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Property Plant And Equipment [Line Items]
Less: Accumulated depreciation and amortization	$ (295)	$ (270)
Property and equipment, net	29	70
Computer Equipment and Software [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 324	$ 340

Net Loss per Share (Tables)

9 Months Ended

Sep. 30, 2023

Earnings Per Share [Abstract]

Basic and Diluted Net Loss per Share

Basic and diluted net loss per share was calculated as follows:


	Three Months Ended September 30,						Nine Months Ended September 30,
	2023			2022			2023			2022
Numerator:
Net loss	$	(1,827	)	$	(6,368	)	$	(8,393	)	$	(22,782	)

Denominator:
Weighted average common shares outstanding—basic and diluted		4,541,167			4,541,179			4,541,167			4,538,707

Net loss per share —basic and diluted	$	(0.40	)	$	(1.40	)	$	(1.85	)	$	(5.02	)

Summary of Potential Common Shares Excluded from Calculation of Diluted Net Loss per Share

The following potential shares of common stock, presented based on amounts outstanding at each period end, were excluded from the calculation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect:


	Nine Months Ended September 30,
	2023		2022
Warrants to purchase common stock		646,759		646,759
Stock options to purchase common stock		468,617		539,198
Total		1,115,376		1,185,957

Commitments and Contingencies

9 Months Ended

Sep. 30, 2023

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

12. Commitments and Contingencies

Intellectual Property Licenses

Harvard and Dana-Farber Agreement

In August 2006, the Company entered into an exclusive license agreement with President and Fellows of Harvard College (“Harvard”) and Dana-Farber Cancer Institute (“DFCI”). The agreement granted the Company an exclusive worldwide license, with the right to sublicense, under specified patents and patent applications to develop, obtain regulatory approval for and commercialize specified product candidates based on cell-permeating peptides. Under the agreement, the Company is obligated to use commercially reasonable efforts to develop and commercialize one or more licensed products and to achieve specified milestone events by specified dates. In connection with entering into the agreement, the Company paid an upfront license fee and issued to Harvard and DFCI shares of its common stock.

In February 2010, the agreement was amended and restated (the “Harvard/DFCI agreement”) under which additional patent rights were added to the scope of the license agreement and the annual license maintenance fees were increased. Under the Harvard/DFCI agreement, the Company is obligated to make aggregate milestones payments of up to $7,700 per licensed therapeutic product upon the Company’s achievement of specified clinical, regulatory and sales milestones with respect to such product and up to $700 per licensed diagnostic product upon the Company’s achievement of specified regulatory and sales milestones with respect to such product. In addition, the Company is obligated to pay royalties of low single-digit percentages on annual net sales of licensed products sold by the Company, its affiliates or its sublicensees. The royalties are payable on a product-by-product and country-by-country basis, and may be reduced in specified circumstances. In addition, the Harvard/DFCI agreement obligates the Company to pay a percentage, up to the mid-twenties, of fees received by the Company in connection with its sublicense of the licensed products. In accordance with the terms of the Harvard/DFCI agreement, the Company’s sublicense payment obligations may be subject to specified reductions.

From time to time, the Company, Harvard, and DFCI have modified the scope of the agreement. In the quarter ended September 30, 2023, the annual license fees the Company is required to pay under the Harvard/DFCI agreement were modified from $110 to $35. Any payments made in connection with the annual license maintenance fees will be credited against any royalties due.

The Company incurred license maintenance fees of $35 and $110 during each of the nine months ended September 30, 2023 and 2022, respectively. The Company did not make any milestone payments during the three and nine months ended September 30, 2023 and 2022, respectively. As of September 30, 2023, no additional milestones had been achieved and no liabilities for additional milestone payments had been recorded in the Company’s financial statements.

As of September 30, 2023, the Company had not developed a commercial product using the licensed technologies and no royalties under the Harvard/DFCI agreement had been paid or were due.

Under the Harvard/DFCI agreement, the Company is responsible for all patent expenses related to the prosecution and maintenance of the licensed patents and applications in-licensed under the agreement as well as cost reimbursement of amounts incurred for all documented patent-related expenses. The agreement will expire on a product-by-product and country-by-country basis upon the last to expire of any valid patent claim pertaining to licensed products covered under the agreement.

Umicore Agreement

In December 2006, the Company entered into a license agreement with Materia, Inc. (“Materia”), under which it was granted a non-exclusive worldwide license, with the right to sublicense, under specified patent and patent applications to utilize Materia’s catalysts to develop, obtain regulatory approval for and commercialize specified peptides owned or controlled by Materia and the right to manufacture specified compositions owned or controlled by Materia. In February 2017, Materia assigned the license agreement (the “Umicore agreement”) to Umicore Precious Metals Chemistry USA, LLC (“Umicore”), and Umicore agreed to continue to supply the Company under the agreement.

Under the Umicore agreement, the Company is obligated to make aggregate milestone payments to Umicore of up to $6,400 upon the Company’s achievement of specified clinical, regulatory and sales milestones with respect to each licensed product. In addition, the Company is obligated to pay tiered royalties ranging in the low single-digit percentages on annual net sales of licensed products sold by the Company or its sublicensees. The royalties are payable on a product-by-product and country-by-country basis and may be reduced in specified circumstances.

The Umicore agreement requires the Company to pay annual license fees of $50. The Company incurred license fees of $50 during the nine months ended September 30, 2023 and 2022, respectively. The Company did not make any milestone payments during the three and nine months ended September 30, 2023 and 2022, respectively. As of September 30, 2023, no additional milestones had been achieved and no liabilities for additional milestone payments had been recorded in the Company’s financial statements.

The Umicore agreement expires upon the expiration of the Company’s obligation to pay royalties in each territory covered under the agreement.

Indemnification Agreements

In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, business partners and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with members of its board of directors and officers that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. To date, the Company has not incurred any material costs as a result of such indemnifications. The Company is not aware of any claims for indemnification that would have a material effect on its financial position, results of operations or cash flows, and it had not accrued any liabilities related to such obligations in its financial statements as of September 30, 2023 or December 31, 2022.

Summary of Significant Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Sep. 30, 2023
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting periods. Significant estimates and assumptions reflected in these financial statements include, but are not limited to, the accrual of research and development expenses and the valuation of common stock and stock-based awards. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results could differ from the Company’s estimates.
Unaudited Interim Financial Information	Unaudited Interim Financial Information The accompanying unaudited condensed financial statements as of September 30, 2023 and for the nine months ended September 30, 2023 and 2022 have been prepared by the Company pursuant to the rules and regulations of the United States Securities and Exchange Commission (“SEC”) for interim financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. However, the Company believes that the disclosures are adequate to make the information presented not misleading. These financial statements should be read in conjunction with the Company’s audited financial statements and the notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2022 that was filed with the SEC on March 20, 2023. The unaudited interim condensed financial statements have been prepared on the same basis as the audited financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of September 30, 2023, the results of its operations for the three and nine months ended September 30, 2023 and 2022 and its cash flows for the nine months ended September 30, 2023 and 2022. The financial data and other information disclosed in these notes related to the three and nine months ended September 30, 2023 and 2022 are unaudited. The results for the nine months ended September 30, 2023 are not necessarily indicative of results to be expected for the year ending December 31, 2023, any other interim periods, or any future year or period. The accompanying balance sheet as of December 31, 2022 has been derived from the Company’s audited financial statements for the year ended December 31, 2022 included in the Company’s Annual Report on Form 10-K that was filed with the SEC on March 20, 2023. Our significant accounting policies are described in Note 2 to the financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2022 that was filed with the SEC on March 20, 2023.
Concentration of Credit Risk and of Significant Suppliers	Concentration of Credit Risk and of Significant Suppliers Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash, and cash equivalents. From time to time, the Company has maintained all of its cash, cash equivalents and investment balances at three accredited financial institutions, in amounts that exceed federally insured limits. The Company generally invests its excess cash in money market funds, commercial paper and corporate notes that are subject to minimal credit and market risks. Management has established guidelines relative to credit ratings and maturities intended to safeguard principal balances and maintain liquidity. The investment portfolio is maintained in accordance with the Company’s investment policy, which defines allowable investments, specifies credit quality standards and limits the credit exposure of any single issuer. Prior to the February 2023 decision to discontinue development of ALRN-6924, the Company was dependent on third-party manufacturers to supply products for research and development activities of its programs, including preclinical and clinical testing. In particular, the Company relied on a small number of manufacturers to supply it with its requirements for the active pharmaceutical ingredients and formulated drugs related to these programs. These programs could have been adversely affected by a significant interruption in the supply of active pharmaceutical ingredients and formulated drugs.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (ASU 2016-13 or Topic 326): Measurement of Credit Losses on Financial Instruments, which requires the measurement and recognition of expected credit losses for financial assets held at amortized cost. ASU 2016-13 replaces the existing incurred loss impairment model with an expected loss methodology, which will result in more timely recognition of credit losses. The ASU was effective for the Company's fiscal year beginning January 1, 2023, and adoption did not have a material effect on the Company’s financial statements or disclosures. Other accounting standards that have been issued or proposed by the FASB or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on the Company’s financial statements upon adoption.

Summary of Significant Accounting Policies	9 Months Ended
Summary of Significant Accounting Policies	Sep. 30, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting periods. Significant estimates and assumptions reflected in these financial statements include, but are not limited to, the accrual of research and development expenses and the valuation of common stock and stock-based awards. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results could differ from the Company’s estimates. Unaudited Interim Financial Information The accompanying unaudited condensed financial statements as of September 30, 2023 and for the nine months ended September 30, 2023 and 2022 have been prepared by the Company pursuant to the rules and regulations of the United States Securities and Exchange Commission (“SEC”) for interim financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. However, the Company believes that the disclosures are adequate to make the information presented not misleading. These financial statements should be read in conjunction with the Company’s audited financial statements and the notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2022 that was filed with the SEC on March 20, 2023. The unaudited interim condensed financial statements have been prepared on the same basis as the audited financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of September 30, 2023, the results of its operations for the three and nine months ended September 30, 2023 and 2022 and its cash flows for the nine months ended September 30, 2023 and 2022. The financial data and other information disclosed in these notes related to the three and nine months ended September 30, 2023 and 2022 are unaudited. The results for the nine months ended September 30, 2023 are not necessarily indicative of results to be expected for the year ending December 31, 2023, any other interim periods, or any future year or period. The accompanying balance sheet as of December 31, 2022 has been derived from the Company’s audited financial statements for the year ended December 31, 2022 included in the Company’s Annual Report on Form 10-K that was filed with the SEC on March 20, 2023. Our significant accounting policies are described in Note 2 to the financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2022 that was filed with the SEC on March 20, 2023. Concentration of Credit Risk and of Significant Suppliers Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash, and cash equivalents. From time to time, the Company has maintained all of its cash, cash equivalents and investment balances at three accredited financial institutions, in amounts that exceed federally insured limits. The Company generally invests its excess cash in money market funds, commercial paper and corporate notes that are subject to minimal credit and market risks. Management has established guidelines relative to credit ratings and maturities intended to safeguard principal balances and maintain liquidity. The investment portfolio is maintained in accordance with the Company’s investment policy, which defines allowable investments, specifies credit quality standards and limits the credit exposure of any single issuer. Prior to the February 2023 decision to discontinue development of ALRN-6924, the Company was dependent on third-party manufacturers to supply products for research and development activities of its programs, including preclinical and clinical testing. In particular, the Company relied on a small number of manufacturers to supply it with its requirements for the active pharmaceutical ingredients and formulated drugs related to these programs. These programs could have been adversely affected by a significant interruption in the supply of active pharmaceutical ingredients and formulated drugs. Recently Issued Accounting Pronouncements In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (ASU 2016-13 or Topic 326): Measurement of Credit Losses on Financial Instruments, which requires the measurement and recognition of expected credit losses for financial assets held at amortized cost. ASU 2016-13 replaces the existing incurred loss impairment model with an expected loss methodology, which will result in more timely recognition of credit losses. The ASU was effective for the Company's fiscal year beginning January 1, 2023, and adoption did not have a material effect on the Company’s financial statements or disclosures. Other accounting standards that have been issued or proposed by the FASB or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on the Company’s financial statements upon adoption.

Restructuring and Other Costs

9 Months Ended

Sep. 30, 2023

Restructuring and Related Activities [Abstract]

Restructuring and Other Costs

8. Restructuring and Other Costs

On February 16, 2023, the Board of Directors of the Company determined to reduce the Company’s remaining workforce from nine to three full-time employees. The determination to effect the workforce reduction was made in connection with the Company’s decision to terminate its Phase 1b breast cancer trial of ALRN-6924 and further development of ALRN-6924.

As a result of the above restructuring initiatives, the Company incurred restructuring-related charges of $940 for the nine months ended September 30, 2023. Restructuring-related charges were comprised of one-time termination costs in connection with the reduction-in-workforce, including severance, benefits, and related costs.

As of September 30, 2023, the short-term portion of the accrued restructuring balance, or $12, is included in “Accrued expenses and other current liabilities” in the accompanying balance sheets. The Company paid $10 and $928, respectively, in costs during the three and nine months ended September 30, 2023, and expects that payment of these remaining costs will be made through the fourth quarter of 2023.

Net Loss per Share

9 Months Ended

Sep. 30, 2023

Earnings Per Share [Abstract]

Net Loss per Share

11. Net Loss per Share

Basic and diluted net loss per share was calculated as follows:


	Three Months Ended September 30,						Nine Months Ended September 30,
	2023			2022			2023			2022
Numerator:
Net loss	$	(1,827	)	$	(6,368	)	$	(8,393	)	$	(22,782	)

Denominator:
Weighted average common shares outstanding—basic and diluted		4,541,167			4,541,179			4,541,167			4,538,707

Net loss per share —basic and diluted	$	(0.40	)	$	(1.40	)	$	(1.85	)	$	(5.02	)

The Company’s potential dilutive securities as of September 30, 2023 and 2022, which include stock options and warrants, have been excluded from the computation of diluted net loss per share whenever the effect of including them would be to reduce the net loss per share. In periods where there is a net loss, the weighted average number of shares of common stock outstanding used to calculate both basic and diluted net loss per share is the same. The following potential shares of common stock, presented based on amounts outstanding at each period end, were excluded from the calculation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect:


	Nine Months Ended September 30,
	2023		2022
Warrants to purchase common stock		646,759		646,759
Stock options to purchase common stock		468,617		539,198
Total		1,115,376		1,185,957

Fair Value of Financial Assets - Summary of Assets Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments		$ 16,048
Commercial Paper [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments		12,814
Treasury Bills [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments		3,234
Recurring [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total Fair Value of Financial Instruments	$ 10,903	17,709
Recurring [Member] \| Level 1 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total Fair Value of Financial Instruments	10,903	1,661
Recurring [Member] \| Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total Fair Value of Financial Instruments		16,048
Recurring [Member] \| Commercial Paper [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments		12,814
Recurring [Member] \| Commercial Paper [Member] \| Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments		12,814
Recurring [Member] \| Treasury Bills [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments		3,234
Recurring [Member] \| Treasury Bills [Member] \| Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Investments		3,234
Recurring [Member] \| Money Market Funds [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents	10,903	1,661
Recurring [Member] \| Money Market Funds [Member] \| Level 1 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents	$ 10,903	$ 1,661

Accrued Expenses and Other Current Liabilities

9 Months Ended

Sep. 30, 2023

Payables and Accruals [Abstract]

Accrued Expenses and Other Current Liabilities

6. Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following:


	September 30, 2023		December 31, 2022
External research and development services	$	20	$	533
Payroll and payroll-related costs		103		425
Professional fees		995		492
Restructuring and other costs (Note 8)		12		—
Other		10		181
	$	1,140	$	1,631

Condensed Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 12,069	$ 5,194
Investments		16,048
Prepaid expenses and other current assets	699	606
Restricted cash	25	25
Total current assets	12,793	21,873
Operating lease, right-of-use asset		40
Other non-current assets		24
Property and equipment, net	29	70
Total assets	12,822	22,007
Current liabilities:
Accounts payable	484	1,720
Accrued expenses and other current liabilities	1,140	1,631
Operating lease liability, current portion		33
Total current liabilities	1,624	3,384
Total liabilities	1,624	3,384
Commitments and contingencies (Note 12)
Stockholders’ equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized and no shares issued and outstanding at September 30, 2023 and December 31, 2022, respectively
Common stock, $0.001 par value; 45,000,000 shares authorized at September 30, 2023 and December 31, 2022, respectively; 4,541,167 shares issued and outstanding at September 30, 2023 and December 31, 2022, respectively	91	91
Additional paid-in capital	292,285	291,365
Accumulated other comprehensive loss		(48)
Accumulated deficit	(281,178)	(272,785)
Total stockholders’ equity	11,198	18,623
Total liabilities and stockholders’ equity	$ 12,822	$ 22,007

Property and Equipment, Net (Tables)

9 Months Ended

Sep. 30, 2023

Property, Plant and Equipment [Abstract]

Summary of Property and Equipment, Net

Property and equipment, net consisted of the following:


	September 30, 2023			December 31, 2022
Computer equipment and software	$	324		$	340
Less: Accumulated depreciation and amortization		(295	)		(270	)
	$	29		$	70

Restructuring and Other Costs - Additional Information (Details) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2023 USD ($)	Sep. 30, 2023 USD ($) Employees	Dec. 31, 2022 Employees
Restructuring and Related Activities [Abstract]
Workforce reduction, remaining number of employees \| Employees		3	9
Restructuring charges	$ 6	$ 940
Accrued restructuring balance	12	12
Payments for restructuring	$ 10	$ 928

Stock-Based Awards - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands				9 Months Ended
	Jan. 01, 2023	Jan. 01, 2022	Jun. 16, 2017	Sep. 30, 2023	Sep. 30, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average grant-date fair value of stock options					$ 7
Number of options granted to employees or directors				0
Aggregate fair value of stock options vested				$ 1,033	$ 2,420
Aggregate unrecognized stock-based compensation expense				$ 1,630
Unrecognized stock-based compensation expense, weighted average period expects for recognition				1 year 10 months 6 days
Number of stock options exercised				0	0
2021 Stock Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option granted vesting period				4 years
Number of shares, available for grant				796,930
Number of shares remained available for grant				384,193
2021 Stock Incentive Plan [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option granted vesting period				4 years
Stock option expiration period				10 years
2017 Stock Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option granted vesting period				4 years
Stock reserved for future issuance				625,000
2017 Stock Incentive Plan [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option granted vesting period				4 years
Stock option expiration period				10 years
2006 Stock Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Contractual repurchase right, shares				314,006
2017 Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares, available for grant				0
Stock reserved for future issuance			7,500
Percentage of common stock shares outstanding			1.00%
Increase to shares authorized for issuance	0	0
Stock incentive plan description				On June 16, 2017, the Company’s stockholders approved the 2017 Employee Stock Purchase Plan (the “2017 ESPP”), which became effective on June 28, 2017. A total of 7,500 shares of common stock were initially reserved for issuance under this plan. Under the 2017 ESPP, the number of shares of common stock that may be issued under the 2017 ESPP will automatically increase on each January 1, beginning with the fiscal year ending December 31, 2018 and continuing for each fiscal year until, and including, the fiscal year ending December 31, 2027, equal to the least of (i) 31,120 shares, (ii) 1% of the outstanding shares of common stock on such date and (iii) an amount determined by the Company’s board of directors. The compensation committee of the board of directors has determined that the number of shares of common stock that may be issued under the 2017 ESPP would not be increased on January 1, 2022 or January 1, 2023. The Company has not issued any shares under the 2017 ESPP.
Maximum annual increase in common stock reserved for future issuance			31,120

Net Loss per Share - Basic and Diluted Net Loss per Share (Detail) - USD ($) $ / shares in Units, $ 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
Numerator:
Net loss	$ (1,827)	$ (1,787)	$ (4,779)	$ (6,368)	$ (7,992)	$ (8,422)	$ (8,393)	$ (22,782)
Denominator:
Weighted average common shares outstanding - basic	4,541,167			4,541,179			4,541,167	4,538,707
Weighted average common shares outstanding - diluted	4,541,167			4,541,179			4,541,167	4,538,707
Net loss per share - basic	$ (0.4)			$ (1.4)			$ (1.85)	$ (5.02)
Net loss per share - diluted	$ (0.4)			$ (1.4)			$ (1.85)	$ (5.02)

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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-URI https://asc.fasb.org//1943274/2147482662/260-10-50-1

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(25))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(27))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483589/942-220-S99-1

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(23))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483586/944-220-S99-1

Reference 15: http://www.xbrl.org/2003/role/exampleRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 52
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482635/260-10-55-52

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482689/260-10-45-7

+ Details

- Definition

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

+ References

+ Details

Fair Value of Financial Assets

9 Months Ended

Sep. 30, 2023

Fair Value Disclosures [Abstract]

Fair Value of Financial Assets

3. Fair Value of Financial Assets

The following tables present information about the Company’s assets that are measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values:


	Fair Value Measurements as of September 30, 2023 using:
	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	10,903	$	—	$	—	$	10,903
	$	10,903	$	—	$	—	$	10,903


	Fair Value Measurements as of December 31, 2022 using:
	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	1,661	$	—	$	—	$	1,661
Investments:
Commercial paper		—		12,814		—		12,814
Treasury bills		—		3,234		—		3,234
	$	1,661	$	16,048	$	—	$	17,709

As of September 30, 2023 and December 31, 2022, the Company’s cash equivalents and investments were invested in money market funds, commercial paper and treasury bills and valued based on Level 1 and Level 2 inputs. In determining the fair value of its commercial paper at each date presented above, the Company relied on quoted prices for similar securities in active markets or using other inputs that are observable or can be corroborated by observable market data. The Company’s cash equivalents have original maturities of less than 90 days from the date of purchase. All available-for-sale investments have contractual maturities of less than one year. During the nine months ended September 30, 2023 and the year ended December 31, 2022, there were no transfers in or out of Level 3.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Lease

9 Months Ended

Sep. 30, 2023

Leases [Abstract]

Lease

7. Lease

On March 26, 2021, the Company entered into a sublease agreement (the “Sublease”) by and among the Company, Vittoria Industries North America, Inc. (the “Sublessor”) and Waterfront Equity Partners, LLC (the “Lessor”), under which the Company was leasing approximately 3,365 square feet of office space located at 285 Summer Street, Unit 101, Boston, Massachusetts (the “Premises”). The Sublease was subject and subordinate to a lease agreement, dated as of July 13, 2012, by and between the Sublessor

and Lessor (the “Prime Lease”), pursuant to which the Sublessor is leasing the Premises from the Lessor. The Sublease expired March 31, 2023 and the Company did not renew the Sublease. Following expiration of the Sublease, the Company is operating virtually, and expects to do so for the foreseeable future.

Lease - Additional Information (Detail) - Sublease [Member] - ft²	9 Months Ended
	Sep. 30, 2023	Mar. 26, 2021
Lessee Lease Description [Line Items]
Lease termination date	Mar. 31, 2023
Boston, Massachusetts [Member]
Lessee Lease Description [Line Items]
Area of land		3,365

Fair Value of Financial Assets - Additional Information (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Available-for-sale investments, maximum contractual maturity period	1 year
Fair Value, assets transfers into (out of) Level 3	$ 0	$ 0

Nature of the Business and Basis of Presentation - Additional Information (Detail) $ in Thousands		9 Months Ended	12 Months Ended
	Nov. 10, 2022 shares	Sep. 30, 2023 USD ($) Employees shares	Dec. 31, 2022 USD ($) Employees shares	Nov. 09, 2022 shares	Jun. 16, 2021 shares	Dec. 31, 2020 shares
Class of Stock [Line Items]
Proceeds from collaboration agreement		$ 34,910
Cash and cash equivalents		12,069	$ 5,194
Accumulated deficit		$ (281,178)	$ (272,785)
Workforce reduction, remaining number of employees \| Employees		3	9
Common stock, shares authorized \| shares	15,000,000	45,000,000	45,000,000	300,000,000	15,000,000	7,500,000
Reverse stock split, description	On November 10, 2022, the Company effected a one-for-twenty reverse stock split on its common stock (the “Reverse Stock Split”). The Reverse Stock Split was reflected on the Nasdaq Capital Market beginning with the opening of trading on November 11, 2022. Pursuant to the Reverse Stock Split, every 20 shares of the Company's issued and outstanding shares of common stock were automatically combined into one issued and outstanding share of common stock, without any change in the par value per share of the common stock. The Reverse Stock Split reduced the authorized number of shares of common stock from 300,000,000 to 15,000,000 and, pursuant to the certificate of amendment, such reduced authorized number of shares of common stock was subsequently multiplied by three, such that following the Reverse Stock Split the Company has 45,000,000 shares of common stock authorized. The Reverse Stock Split affected all issued and outstanding shares of the Company's common stock, and the respective numbers of shares of common stock underlying the Company’s outstanding stock options, outstanding warrants and the Company's equity incentive plans were proportionately adjusted. All share and per share amounts of the common stock included in the accompanying financial statements have been retrospectively adjusted to give effect to the Reverse Stock Split for all periods presented.
Reverse stock split conversion ratio	0.05
Common Stock [Member]
Class of Stock [Line Items]
Proceeds from sales of stock		$ 145,467
Preferred Stock [Member]
Class of Stock [Line Items]
Proceeds from sales of stock		$ 131,211

Investments

9 Months Ended

Sep. 30, 2023

Investments, Debt and Equity Securities [Abstract]

Investments

4. Investments

The Company had no investments as of September 30, 2023. As of December 31, 2022, the fair value of available-for-sale investments by type of security was as follows:


	December 31, 2022
	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss			Fair Value
Investments:
Commercial paper	$	12,846	$	—	$	(32	)	$	12,814
Treasury bills		3,250		—		(16	)		3,234
	$	16,096	$	—	$	(48	)	$	16,048

Net Loss per Share - Summary of Potential Common Shares Excluded from Calculation of Diluted Net Loss per Share (Detail) - shares	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares excluded from calculation of diluted net loss per share	1,115,376	1,185,957
Warrants to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares excluded from calculation of diluted net loss per share	646,759	646,759
Stock Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares excluded from calculation of diluted net loss per share	468,617	539,198

Condensed Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
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	$ 0.001	$ 0.001
Common stock, shares authorized	45,000,000	45,000,000
Common stock, shares issued	4,541,167	4,541,167
Common stock, shares outstanding	4,541,167	4,541,167

Fair Value of Financial Assets (Tables)

9 Months Ended

Sep. 30, 2023

Fair Value Disclosures [Abstract]

Summary of Assets Measured at Fair Value on Recurring Basis


	Fair Value Measurements as of September 30, 2023 using:
	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	10,903	$	—	$	—	$	10,903
	$	10,903	$	—	$	—	$	10,903


	Fair Value Measurements as of December 31, 2022 using:
	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	1,661	$	—	$	—	$	1,661
Investments:
Commercial paper		—		12,814		—		12,814
Treasury bills		—		3,234		—		3,234
	$	1,661	$	16,048	$	—	$	17,709

Stock-Based Awards

9 Months Ended

Sep. 30, 2023

Share-Based Payment Arrangement [Abstract]

Stock-Based Awards

10. Stock-Based Awards

2021 Stock Incentive Plan

The Company’s 2021 Stock Incentive Plan (the “2021 Plan”) was approved by the Company’s stockholders on June 15, 2021 and became effective on June 16, 2021. Under the 2021 Plan, the Company may grant incentive stock options, nonstatutory stock options, stock appreciation rights, restricted stock awards, awards of restricted stock units and other stock-based awards. The Company’s employees, officers, directors, consultants and advisors are eligible to receive awards under the 2021 Plan; however, incentive stock options may only be granted to employees. The 2021 Plan is administered by the board of directors or, at the discretion of the board of directors, by a committee of the board. The number of shares of common stock covered by options and the date those options become exercisable, type of options to be granted, exercise prices, vesting and other restrictions are determined at the discretion of the board of directors, or its committee if so delegated.

Stock options granted under the 2021 Plan with service-based vesting conditions generally vest over four years and may not have a duration in excess of ten years, although options have been granted with vesting terms of less than four years.

The total number of shares of common stock that may be issued under the 2021 Plan was 796,930 as of September 30, 2023, of which 384,193 shares remained available for grant. The Company initially reserved 625,000 shares of common stock, plus the number of shares of common stock subject to outstanding awards under the Company’s 2017 Stock Incentive Plan (the “2017 Plan”), and the Company’s 2016 Stock Incentive Plan (“the 2016 Plan”) and the Company’s 2006 Stock Incentive Plan, as amended (the “2006 Plan”) that expire, terminate or are otherwise surrendered, canceled, forfeited or repurchased by the Company at their original issuance price pursuant to a contractual repurchase right up to 314,006 shares.

Shares that are expired, terminated, surrendered or canceled without having been fully exercised will be available for future awards. In addition, shares of common stock that are tendered to the Company by a participant to exercise an award are added to the number of shares of common stock available for the grant of awards.

The exercise price for stock options granted may not be less than the fair market value of the common stock as of the date of grant.

2017 Stock Incentive Plan

The 2017 Plan was approved by the Company’s stockholders on June 16, 2017, and became effective on June 28, 2017. Under the 2017 Plan, the Company could grant incentive stock options, nonstatutory stock options, stock appreciation rights, restricted stock awards, awards of restricted stock units and other stock-based awards. The Company’s employees, officers, directors, consultants and advisors were eligible to receive awards under the 2017 Plan; however, incentive stock options could only be granted to employees. The 2017 Plan is administered by the board of directors or, at the discretion of the board of directors, by a committee of the board. The number of shares of common stock covered by options and the date those options become exercisable, type of options granted, exercise prices, vesting and other restrictions were determined at the discretion of the board of directors, or its committee if so delegated.

Stock options granted under the 2017 Plan with service-based vesting conditions generally vest over four years and may not have a duration in excess of ten years, although options have been granted with vesting terms of less than four years. The exercise price for stock options granted may not be less than the fair market value of the common stock as of the date of grant.

As of the effective date of the 2021 Plan, the board of directors determined to grant no further awards under the 2017 Plan.

Shares that are expired, terminated, surrendered or canceled without having been fully exercised will be available for future awards under the 2021 Plan. In addition, shares of common stock that are tendered to the Company by a participant to exercise an award are added to the number of shares of common stock available for the grant of awards under the 2021 Plan.

2017 Employee Stock Purchase Plan

On June 16, 2017, the Company’s stockholders approved the 2017 Employee Stock Purchase Plan (the “2017 ESPP”), which became effective on June 28, 2017. A total of 7,500 shares of common stock were initially reserved for issuance under this plan. Under the 2017 ESPP, the number of shares of common stock that may be issued under the 2017 ESPP will automatically increase on each January 1, beginning with the fiscal year ending December 31, 2018 and continuing for each fiscal year until, and including, the fiscal year ending December 31, 2027, equal to the least of (i) 31,120 shares, (ii) 1% of the outstanding shares of common stock on such date and (iii) an amount determined by the Company’s board of directors. The compensation committee of the board of directors has determined that the number of shares of common stock that may be issued under the 2017 ESPP would not be increased on January 1, 2022 or January 1, 2023. The Company has not issued any shares under the 2017 ESPP.

Stock Option Valuation

There were no options granted to employees or directors during the nine months ended September 30, 2023. The assumptions that the Company used to determine the grant-date fair value of the stock options granted to employees and directors during the nine months ended September 30, 2022 were as follows, presented on a weighted average basis :


	Nine Months Ended September 30, 2022
Risk-free interest rate		2.46	%
Expected term (in years)		5.9
Expected volatility		94.2	%
Expected dividend yield		0	%

Stock Options

The following table summarizes the Company’s stock option activity since January 1, 2023:


	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
						(in years)
Outstanding at December 31, 2022		537,112		$	29.77		7.9	$	—
Granted		—
Exercised		—
Canceled, forfeited or expired		(68,495	)
Outstanding at September 30, 2023		468,617		$	31.76		6.4	$	—
Options exercisable at September 30, 2023		354,371		$	35.80		5.9	$	—
Options vested and expected to vest at September 30, 2023		465,772		$	31.84		6.4	$	—
Options exercisable at December 31, 2022		288,821		$	40.15		7.1	$	—
Options vested and expected to vest at December 31, 2022		529,549		$	29.95		7.8	$	—

There were no options granted to employees or directors during the nine months ended September 30, 2023. The weighted average grant-date fair value of stock options granted during the nine months ended September 30, 2022 was $7.00.

The aggregate fair value of stock options that vested during the nine months ended September 30, 2023 and 2022 was $1,033 and $2,420, respectively.

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. There were no stock options exercised during the nine months ended September 30, 2023 and 2022.

Restricted Stock Units

The Company did not have any restricted stock activity during the nine months ended September 30, 2023.

Stock-Based Compensation

The Company recorded stock-based compensation expense related to stock options and restricted stock units in the following expense categories of its statements of operations and comprehensive loss:


	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
Research and development expenses	$	37	$	144	$	227	$	465
General and administrative expenses		192		298		693		1,194
	$	229	$	442	$	920	$	1,659

As of September 30, 2023, the Company had an aggregate of $1,630 of unrecognized stock-based compensation expense, which it expects to recognize over a weighted average period of 1.85 years.