In November 2021, our Board adopted, and our stockholders approved, the 2021 Equity and Incentive Plan (the “2021 Equity Plan”), which became effective on November 4, 2021. The 2021 Equity Plan provides for the grant of incentive stock options, non-statutory stock options, stock appreciation rights, restricted stock, restricted stock units and other stock-based awards. The number of shares of our common stock reserved for issuance under the 2021 Equity Plan is equal to 2,496,934, subject to an annual increase, to be added on the first day of each fiscal year, beginning with the fiscal year ending December 31, 2022 and continuing until, and including, the fiscal year ending December 31, 2031, equal to the lesser of (i) 4% of the number of shares of common stock outstanding on the first day of such fiscal year or (ii) such other amount determined by our Board. As of June 30, 2025, we had 486,563 shares available for future grant under the 2021 Equity Plan.

In November 2021, our Board adopted and our stockholders approved the 2021 Employee Stock Purchase Plan (the “2021 ESPP”), which became effective on November 4, 2021. The number of shares of our common stock reserved for issuance under the 2021 ESPP is equal to 257,272, subject to an annual increase, to be added on the first day of each fiscal year, beginning January 1, 2023, equal to the lesser of (1) 1% of the number of shares of common stock outstanding on the first day of such fiscal year; (2) 257,272 shares of our common stock; or (3) such other amount as determined by our Board. As of June 30, 2025, the Board had not yet approved any offerings under the 2021 ESPP.

In September 2023, our Board adopted the 2023 Inducement Award Plan (the “2023 Inducement Plan”), which became effective on September 28, 2023. The 2023 Inducement Plan provides for the grant of non-statutory stock options, stock appreciation rights, restricted stock, restricted stock units and other stock-based awards to eligible employees who satisfy the standards for inducement grants under Nasdaq Global Market rules. The number of shares of our common stock reserved for issuance under the 2023 Inducement Plan is equal to 1,976,427. As of June 30, 2025, there were 1,666,427 shares available for future grant under the 2023 Inducement Plan.

The following table summarizes our stock options activity for the six months ended June 30, 2025:


	Number of stock options			Weighted- average exercise price per share		Weighted- average remaining contractual term (in years)		Aggregate intrinsic value (in thousands)
Outstanding, January 1, 2025		8,967,605		$	5.18		8.1	$	1
Granted		2,709,284		$	1.13			$	—
Cancelled or forfeited		(137,589	)	$	4.28			$	—
Outstanding, June 30, 2025		11,539,300		$	4.24		8.1	$	821
Exercisable, June 30, 2025		5,537,588		$	6.87		7.2	$	57

All share-based awards granted are measured based on the fair value on the date of the grant and compensation expense is recognized with respect to those awards over the requisite service period, which is generally the vesting period of the respective award. Forfeitures related to equity-based compensation awards are recognized as they occur, and we reverse any previously recognized compensation cost associated with forfeited awards in the period the forfeiture occurs.

As of June 30, 2025, there was $7.2 million of unrecognized compensation cost related to unvested stock-based compensation arrangements that is expected to be recognized over a weighted average period of 2.8 years.

The fair values of the stock options granted during the period ended June 30, 2025 were estimated based on the Black-Scholes model, using the following assumptions:


	Six Months Ended
	June 30, 2025
Expected volatility	84.4 - 85.2
Risk-free interest rate	3.9 - 4.2
Expected term (in years)	5.5 - 6.1
Expected dividend yield		0	%

Equity-based compensation expense recorded as research and development and general and administrative expenses is as follows (in thousands):


	Three Months Ended June 30,				Six Months Ended June 30,
	2025		2024		2025		2024
Research and development	$	644	$	677	$	1,262	$	1,290
General and administrative		963		965		1,914		1,920
Total equity-based compensation	$	1,607	$	1,642	$	3,176	$	3,210

We did not recognize any tax benefits for stock-based compensation during the three and six months ended June 30, 2025 and 2024.