Stock-Based Compensation

3 Months Ended

Mar. 31, 2024

Share-Based Payment Arrangement [Abstract]

Stock Incentive Plan

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.

In August 2021, the Company's stockholders approved the 2021 Plan under which stock options, restricted stock units 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 March 31, 2024, the Company had 6,731,840 shares available for future issuance under the 2021 Plan.

The 2023 Inducement Plan (the Inducement Plan) became effective upon approval of the Company's board of directors in February 2023. The Inducement Plan allows the Company to make equity and equity-based incentive awards to individuals who were not previously employees or directors of the Company. As of March 31, 2024, the Company had 2,057,750 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 March 31,
	2024		2023
	(in thousands)
Research and development	$	3,806	$	2,135
General and administrative		2,913		2,084
Total	$	6,719	$	4,219

Stock Option Activity

The following table summarizes the stock option activity for the three months ended March 31, 2024:


	Number of Shares			Weighted Average Exercise Price		Weighted Average Contractual Term		Aggregate Intrinsic Value
						(in years)
Options outstanding as of December 31, 2023		16,734,960		$	6.21		7.83	$	62,640,906
Granted		4,288,631		$	12.12
Exercised		(333,511	)	$	3.81
Cancelled		(100,855	)	$	7.14
Options outstanding as of March 31, 2024		20,589,225		$	7.47		8.00	$	37,007,114
Options exercisable as of March 31, 2024		9,348,930		$	5.95		7.04	$	24,344,914

As of March 31, 2024, total unrecognized compensation expense related to stock options was $63.6 million, which the Company expects to recognize over a remaining weighted-average period of 2.7 years.

Restricted Stock Unit Activity

The following table summarizes the RSU activity for the three months ended March 31, 2024:


	Number of Stock Units			Weighted Average Grant Date Fair Value Per Share
Unvested and outstanding as of December 31, 2023		757,514		$	5.25
Granted		709,718			12.14
Vested		(197,925	)		5.18
Forfeited		(14,851	)		6.24
Unvested and outstanding as of March 31, 2024		1,254,456		$	9.15

As of March 31, 2024, total unrecognized compensation expense related to RSUs was $10.7 million, which the Company expects to recognize over a remaining weighted-average period of 2.4 years.

2021 Employee Stock Purchase Plan

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 upon the closing of the Business Combination. During the three months ended March 31, 2024, the Company issued zero shares of common stock under the 2021 ESPP.