Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2023

Stock-Based Compensation

Schedule of stock option activity

		Weighted		Weighted
		Average		Average
		Exercise		Remaining
		Price		Contractual
	Shares	Per Share		Term (In Years)
Options outstanding at December 31, 2022	5,085,662	$	29.26	7.9
Granted	1,612,175	$	36.58	—
Exercised	(131,203)	$	14.92	—
Canceled	(187,710)	$	87.30	—
Options outstanding at December 31, 2023	6,378,924	$	29.69	7.5
Options vested and expected to vest at December 31, 2023	6,264,180	$	29.67	7.5
Options exercisable at December 31, 2023	3,261,890	$	29.21	6.4
Shares available for grant under the 2021 Plan	1,013,503		—	—

Schedule of stock-based compensation expense

	2023		2022		2021
	(In thousands)
Research and development	$	11,948	$	8,082	$	4,525
General and administrative		11,942		7,529		4,428
Total stock-based compensation expense	$	23,890	$	15,611	$	8,953

Schedule of assumptions used for the fair value of employee stock options granted

	2023	2022	2021
Expected stock price volatility	92%	90 - 97%	97 - 98%
Expected option term	6.0 Years	6.0 Years	6.0 Years
Risk-free interest rate	3.5 - 4.7%	1.7 - 4.2%	0.8 - 1.4%
Expected dividend yield	None	None	None