Stock-based compensation (Tables)

3 Months Ended

Mar. 31, 2024

Stock-based compensation

Compensation cost recognized for all stock-based compensation awards

	Three Months Ended
	March 31,
	2024		2023
	(in thousands)
Research and development	$	1,280	$	863
General and administrative		2,293		1,695
Total stock-based compensation expense	$	3,573	$	2,558

Summary of stock-based compensation expense by type of award

	Three Months Ended
	March 31,
	2024		2023
	(in thousands)
Stock options	$	2,408	$	1,663
Restricted stock awards and units		1,090		841
Employee stock purchase plan awards		75		54
Total stock-based compensation expense	$	3,573	$	2,558

Summary of status and changes in unvested restricted stock

		Weighted
		Average
		Grant Date
		Fair Value
	Units	Per Unit
Unvested restricted stock units as of December 31, 2023	1,370,897	$	6.65
Granted	696,908	$	7.63
Vested	(324,520)	$	5.75
Forfeited	(23,947)	$	6.42
Unvested restricted stock units as of March 31, 2024	1,719,338	$	7.22

Summary of stock option activity

		Weighted		Remaining	Aggregate
		Average		Contractual	Intrinsic
		Exercise		Life	Value
	Shares	Price		(in years)	(in thousands)
Outstanding at December 31, 2023	7,425,444	$	8.52
Granted	1,747,626	$	7.68
Exercised	(32,500)	$	4.91
Cancelled or forfeited	(230,974)	$	12.28
Outstanding at March 31, 2024	8,909,596	$	8.27	7.8	$	17,875
Exercisable at March 31, 2024	3,880,357	$	9.04	6.2	$	8,728