Stock-based compensation (Tables)

3 Months Ended

Mar. 31, 2023

Stock-based compensation

Compensation cost recognized for all stock-based compensation awards

Total compensation cost recognized for all stock-based compensation awards in the condensed consolidated statements of operations and comprehensive income (loss) is as follows:

	Three Months Ended
	March 31,
	2023		2022
	(in thousands)
Research and development	$	863	$	801
General and administrative		1,695		1,518
Total stock-based compensation expense	$	2,558	$	2,319

Summary of stock-based compensation expense by type of award

	Three Months Ended
	March 31,
	2023		2022
	(in thousands)
Stock options	$	1,663	$	1,477
Restricted stock awards and units		841		792
Employee stock purchase plan awards		54		51
Total stock-based compensation expense	$	2,558	$	2,319

Summary of status and changes in unvested restricted stock

A summary of the status of and changes in unvested restricted stock unit activity under the Company’s equity award plans for the three months ended March 31, 2023 was as follows:

		Weighted
		Average
		Grant Date
		Fair Value
	Units	Per Unit
Unvested restricted stock units as of December 31, 2022	1,112,563	$	5.27
Granted	622,050	$	7.24
Vested	(374,417)	$	5.44
Forfeited	(24,037)	$	3.80
Unvested restricted stock units as of March 31, 2023	1,336,159	$	6.17

Summary of stock option activity

The following is a summary of stock option activity for the three months ended March 31, 2023:

		Weighted		Remaining	Aggregate
		Average		Contractual	Intrinsic
		Exercise		Life	Value
	Shares	Price		(in years)	(in thousands)
Outstanding at December 31, 2022	6,199,571	$	8.12	7.9	$	6,095
Granted	1,358,200	$	7.55
Exercised	(51,993)	$	3.56
Cancelled or forfeited	(145,033)	$	5.42
Outstanding at March 31, 2023	7,360,745	$	8.10	8.0	$	10,631
Exercisable at March 31, 2023	3,133,247	$	10.28	6.4	$	4,025