Stock Based Compensation (Tables)

6 Months Ended

Jun. 30, 2022

Stock Based Compensation

Schedule of weighted average assumption for grant date fair value of stock options

	Three months ended						Six months ended
	June 30,						June 30,
	2022			2021			2022			2021
Risk-free interest rate		2.61	%		1.05	%		1.69	%		0.72	%
Expected dividend yield		0.00	%		0.00	%		0.00	%		0.00	%
Expected term (in years)		5.9			5.9			6.0			6.1
Expected volatility		83.87	%		78.09	%		84.25	%		78.34	%

Schedule of stock option activity

				Weighted
				average
		Weighted		remaining	Aggregate
	Number of	average		contractual term	intrinsic value
	options	exercise price		(in years)	(in thousands)
Balances at December 31, 2021	3,138,646	$	10.74	7.6	$	328
Options granted	2,453,590		2.29
Options cancelled	(560,962)		6.96
Options exercised	(833)		0.57
Outstanding and expected to vest at June 30, 2022	5,030,441		7.04	8.2		32
Exercisable at June 30, 2022	1,915,304	$	7.39	6.6	$	27

Schedule of restricted stock activity

		Weighted
		average grant
	Shares	date fair value
Unvested shares as of December 31, 2021	275,400	$	5.57
Forfeited	(77,500)		5.62
Unvested shares as of June 30, 2022	197,900	$	5.55

Schedule of stock-based compensation expense

	Three months ended				Six months ended
	June 30,				June 30,
	2022		2021		2022		2021
Research and development	$	549	$	871	$	1,064	$	1,710
General and administrative		1,182		1,115		2,285		1,980
	$	1,731	$	1,986	$	3,349	$	3,690