In March 2017, the Company’s stockholders approved the 2017 Stock Option and Grant Plan (the 2017 Plan), under which stock options and restricted stock awards were granted to eligible employees, officers, directors, consultants, or other key persons

who provide services to the Company. Such issuances under the 2017 Plan were subject to vesting, forfeiture and other restrictions as deemed appropriate by the board of directors at the time of issuance.

Upon effectiveness of the 2021 Stock Option and Incentive Plan (the 2021 Plan) in August 2021, the remaining shares available under the 2017 Plan ceased to be available for issuance and no future issuances will be made under the 2017 Plan. The shares of common stock underlying outstanding awards under the 2017 Plan that are forfeited, cancelled, reacquired by the Company prior to vesting, expire or are otherwise terminated (other than by exercise) will be added to the shares of common stock available for issuance under the 2021 Plan.

In August 2021, the Company's board of directors and stockholders approved the 2021 Plan, under which stock options, restricted stock units (RSUs) and other equity-based awards or any combination of these may be granted to eligible employees, officers, directors, consultants, or other key persons who provide services to the Company. Such issuances are subject to vesting, forfeiture and other restrictions as deemed appropriate by the board of directors at the time of issuance. As of June 30, 2025, the Company had 7,480,243 shares available for future issuance under the 2021 Plan.

In February 2023, the Company's board of directors approved the 2023 Inducement Plan (the Inducement Plan), under which the Company reserved shares of common stock, to be used exclusively for grants of non-qualified stock options, restricted stock units and other equity-based awards, or any combination of these to individuals who were not previously employees or directors of the Company. As of June 30, 2025, the Company had 2,041,015 shares available for future issuance under the Inducement Plan.

The Company recorded stock-based compensation expense in the following expense categories in its accompanying condensed consolidated statements of operations:


	Three Months Ended June 30,				Six Months Ended June 30,
	2025		2024		2025		2024
	(in thousands)				(in thousands)
Research and development	$	3,549	$	4,162	$	7,535	$	7,968
General and administrative		3,021		3,376		6,290		6,289
Total	$	6,570	$	7,538	$	13,825	$	14,257

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


	Number of shares			Weighted Average Exercise Price		Weighted Average Contractual Term		Aggregate Intrinsic Value
						(in years)
Options outstanding as of December 31, 2024		19,615,023		$	7.41		7.43	$	2,157,177
Granted		4,846,458		$	2.87
Exercised		(83,137	)	$	2.94
Cancelled		(648,749	)	$	6.61
Options outstanding as of June 30, 2025		23,729,595		$	6.52		7.01	$	20,800,022
Options exercisable as of June 30, 2025		14,337,262		$	6.84		5.86	$	10,326,063

As of June 30, 2025, total unrecognized compensation expense related to stock options was $36.3 million, which the Company expects to recognize over a remaining weighted-average period of 2.6 years.

The following table summarizes the RSU activity for the six months ended June 30, 2025:


	Number of Stock Units			Weighted Average Grant Date Fair Value Per Share
Unvested and outstanding as of December 31, 2024		1,209,333		$	8.92
Granted		792,430			2.87
Vested		(433,483	)		8.62
Forfeited		(154,667	)		6.19
Unvested and outstanding as of June 30, 2025		1,413,613		$	5.92

As of June 30, 2025, total unrecognized compensation expense related to RSUs was $6.7 million, which the Company expects to recognize over a remaining weighted-average period of 2.0 years.

The 2021 Employee Stock Purchase Plan (the 2021 ESPP) was adopted and approved by the Company’s board of directors and by the Company’s stockholders and became effective in August 2021. During the six months ended June 30, 2025, the Company issued 286,300 shares of common stock under the 2021 ESPP.