Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2023

Stock-Based Compensation

Summary 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	1,534,575	$	36.92
Exercised	(46,624)	$	15.63
Canceled	(127,852)	$	31.62
Options outstanding at June 30, 2023	6,445,761	$	31.13	8.0
Options vested and expected to vest at June 30, 2023	6,284,352	$	31.16	7.9
Options exercisable at June 30, 2023	2,896,986	$	33.88	6.7
Shares available for grant under the 2021 Plan	1,031,245

Schedule of stock-based compensation expense

	Three months ended June 30,				Six months ended June 30,
	2023		2022		2023		2022
	(In thousands)				(In thousands)
Research and development	$	2,489	$	1,798	$	4,650	$	3,412
General and administrative		2,728		1,656		4,907		3,195
Total stock-based compensation expense	$	5,217	$	3,454	$	9,557	$	6,607

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

	Three months ended June 30,		Six months ended June 30,
	2023	2022	2023	2022
Expected stock price volatility	92%	90 - 91%	92%	90 – 97%
Expected option term	6.0 Years	6.0 Years	6.0 Years	6.0 Years
Risk-free interest rate	3.5 – 3.9%	2.7 - 3.6%	3.5 – 4.0%	1.7 – 3.6%
Expected dividend yield	None	None	None	None