Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2022

Stock-Based Compensation

Schedule of stock option activity under the Equity Plans

		Weighted
		Average		Weighted	Aggregate
		Exercise Price		Average Remaining	Intrinsic
	Options	Per Share		Life in Years	Value
Outstanding at December 31, 2020	6,393,853		5.29	7.96		1,961
Granted	2,482,650		2.19
Exercised	(2,292)		1.55
Forfeited	(348,593)		3.17
Outstanding at December 31, 2021	8,525,618		4.48	7.58		7,673
Granted	4,024,900		1.50
Forfeited	(633,187)		2.17
Outstanding at December 31, 2022	11,917,331		3.59	7.47
Options exercisable at December 31, 2022	7,543,973		4.74	6.46
Options vested and expected to vest at December 31, 2022	11,917,331		3.59	7.47

Schedule of assumptions used to determine grant-date fair value of stock options

	Year Ended December 31,
	2022		2021
Expected volatility	82.70	%	67.64	%
Weighted average risk-free interest rate	3.10	%	0.82	%
Expected dividend yield	0.00	%	0.00	%
Expected term (in years)	6.42		6.82

Schedule of RSU activity under the 2016 Plan

		Weighted
	Number of	Average Grant
	Shares	Date Fair Value
Outstanding at December 31, 2020	753,106	$	1.52
Awarded	275,000	$	2.57
Settled in cash	(92,500)	$	1.97
Outstanding at December 31, 2021	935,606	$	1.76
Awarded	2,650,000	$	1.94
Outstanding at December 31, 2022	3,585,606	$	1.89

Schedule of recognized stock-based compensation expense related to the issuance of stock option awards and RSUs to employees and non-employees in the condensed consolidated statements of operations

	Year Ended
	December 31,
	2022		2021
Research and development	$	2,540	$	1,641
General and administrative		2,640		2,045
Total	$	5,180	$	3,686