Stock-based compensation (Tables)

9 Months Ended

Sep. 30, 2022

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				Nine Months Ended
	September 30,				September 30,
	2022		2021		2022		2021
	(in thousands)
Research and development	$	588	$	702	$	2,170	$	3,409
General and administrative		1,601		1,375		4,828		6,261
Total stock-based compensation expense	$	2,189	$	2,077	$	6,998	$	9,670

Summary of stock-based compensation expense by type of award

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2022		2021		2022		2021
	(in thousands)
Stock options	$	1,357	$	1,372	$	4,452	$	6,375
Restricted stock awards and units		748		651		2,382		3,018
Employee stock purchase plan awards		84		54		164		277
Total stock-based compensation expense	$	2,189	$	2,077		6,998		9,670

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 nine months ended September 30, 2022 was as follows:

		Weighted
		Average
		Grant Date
		Fair Value
	Units	Per Unit
Unvested restricted stock units as of December 31, 2021	806,379	$	7.26
Granted	770,580	$	3.89
Vested	(419,999)		6.71
Forfeited	(215,685)	$	4.96
Unvested restricted stock units as of September 30, 2022	941,275	$	5.27

Summary of stock option activity

The following is a summary of stock option activity for the nine months ended September 30, 2022:

		Weighted		Remaining	Aggregate
		Average		Contractual	Intrinsic
		Exercise		Life	Value
	Shares	Price		(in years)	(in thousands)
Outstanding at December 31, 2021	5,013,193	$	12.69	5.6	$	1,165
Granted	3,504,675	$	5.14
Exercised	(79,837)	$	7.56
Cancelled or forfeited	(2,358,960)	$	13.22
Outstanding at September 30, 2022	6,079,071	$	8.20	8.1	$	5,693
Exercisable at September 30, 2022	2,581,363	$	10.85	6.4	$	1,838