Stock incentive plans (Tables)

9 Months Ended

Sep. 30, 2022

Stock incentive plans

Allocation of stock-based compensation expenses

Non-cash stock-based compensation expense recognized in the accompanying condensed statements of operations relating to stock options, restricted stock awards, and restricted stock units for the three and nine months ended September 30, 2022 and 2021, was as follows (in thousands):

	Three months ended				Nine months ended
	September 30,				September 30,
	2022		2021		2022		2021
Research and development	$	277	$	634	$	1,096	$	2,047
General and administrative		1,719		1,628		5,531		5,348
Total stock‑based compensation expense	$	1,996	$	2,262	$	6,627	$	7,395

Summary of stock option activity

The table below summarizes activity related to stock options (in thousands, except per share amounts):

				Weighted‑
		Weighted‑		average
		average		remaining	Aggregate
		exercise		contractual	intrinsic
Options	Shares	price		term	value
Outstanding, December 31, 2021	10,713	$	5.36	8.07	$	718
Granted	2,307		2.96
Exercised	—		—
Forfeited and canceled	(1,099)		3.94
Outstanding, September 30, 2022	11,921	$	5.03	7.52	$	—
Vested and expected to vest at September 30, 2022	11,921	$	5.03	7.52	$	—
Exercisable at September 30, 2022	6,541	$	6.61	6.45	$	—