Stock-Based Compensation

12 Months Ended

Dec. 31, 2024

Stock-Based Compensation

Stock-Based Compensation

10. Stock-Based Compensation

Equity Incentive Plans

2020 Stock Incentive Plan

Under the 2020 Stock Incentive Plan (as amended, 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 September 2021, the Company’s board of directors and stockholders adopted the 2021 Stock Incentive Plan (the “2021 Plan”), which became effective immediately prior to the initial public offering 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 Company initially reserved 6,579,016 shares of common stock under the 2021 Plan. The 2021 Plan provides that the number of shares reserved and available for issuance under the 2021 Plan will be cumulatively increased on January 1 of each calendar year by 5% of the number of shares of common stock outstanding on such date or such lesser amount determined by the Company’s board of directors. As of December 31, 2024, there were 1,938,102

shares of common stock available for future issuance under the 2021 Plan. On January 1, 2025, the number of shares reserved for issuance under the 2021 Plan automatically increased by 2,293,405 shares.

2022 Inducement Plan

In 2022, the Company’s board of directors adopted the 2022 Inducement Stock Incentive Plan pursuant to Nasdaq Rule 5635(c)(4) (the “2022 Inducement Plan”). 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. The Company initially reserved 275,000 shares of common stock under the 2022 Inducement Plan. In November 2024, the number of shares reserved for issuance under the 2022 Inducement Plan was increased by 500,000 shares. As of December 31, 2024, there were 610,600 shares of common stock 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 Employee Stock Purchase Plan (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. 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 1% of the number of shares of the Company’s common stock outstanding on such date or such lesser amount determined by the Company’s board of directors (up to a maximum increase of 584,062 shares of common stock per year). During the years ended December 31, 2024 and 2023, the Company issued 76,168 shares and 140,192 shares, respectively, under the 2021 ESPP. As of December 31, 2024, there were 901,208 shares available for future issuance under the 2021 ESPP. On January 1, 2025, the number of shares reserved for issuance under the 2021 ESPP was increased by 458,681 shares.

Stock-Based Compensation Expense

During the years ended December 31, 2024 and 2023, the Company recorded compensation expense related to stock options, restricted stock units and restricted common stock for employees and non-employees, and share purchases under the 2021 ESPP for employees, which was allocated as follows in the consolidated statements of operations and comprehensive loss:

	Year Ended December 31,
	2024		2023
Research and development expense	$	1,652	$	2,189
General and administrative expense		4,782		5,193
Total stock-based compensation expense	$	6,434	$	7,382

Stock Options

A summary of stock option activity under the Company’s Stock Incentive Plans 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, 2023	7,455,795	$	5.52	8.0	$	—
Granted	2,581,453	$	0.86
Exercised	(8,766)	$	0.55
Cancelled/forfeited	(1,694,550)	$	5.18
Outstanding as of December 31, 2024	8,333,932	$	4.15	8.0	$	282
Exercisable as of December 31, 2024	4,132,222	$	5.90	7.1	$	39

(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 years ended December 31, 2024 and 2023 was $0.66 per share and $2.02 per share, respectively. The Company satisfies stock option exercises with newly issued shares of common stock. The aggregate intrinsic value of stock options exercised during each of the years ended December 31, 2024 and 2023 was less than $0.1 million.

The following assumptions were used in determining the fair value of options granted to employees during the years ended December 31, 2024 and 2023:

	Year Ended December 31,
	2024			2023
Risk-free interest rate		3.5 - 4.6	%		3.6 - 4.4	%
Expected dividend yield		0	%		0	%
Expected term (in years)		5.5 - 6.1			5.5 - 6.1
Expected volatility		87.7 -91.5	%		81.7 - 87.3	%

As of December 31, 2024, the Company had unrecognized stock-based compensation expense of $7.3 million related to stock options issued to employees and directors, which is expected to be recognized over a weighted average period of 1.8 years.

Restricted Stock Units

In January 2024, the Company awarded 481,500 restricted stock units to certain employees of the Company. The restricted stock units vest in four equal annual installments beginning on the first anniversary of the grant date. The restricted stock units are generally forfeited if the individual’s service relationship with the Company or any subsidiary terminates prior to vesting.

A summary of the Company’s restricted stock unit activity and related information is as follows:

	Number	Weighted
	of Shares	Average
	of Restricted	Grant Date
	Stock Units	Fair Value
Unvested as of December 31, 2023	—	$	—
Granted	481,500	$	0.55
Forfeited	(36,000)	$	0.55
Unvested as of December 31, 2024	445,500	$	0.55

Restricted Common 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
	Common Stock	Fair Value
Unvested as of December 31, 2023	5,617	$	5.51
Vested	(5,617)	$	5.51
Unvested as of December 31, 2024	—	$	—

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 years ended December 31, 2024 and 2023 was less than $0.1 million.