Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2023

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, 2021	852,266	$	44.76	7.58	$	7,670
Granted	402,490	$	15.03
Forfeited	(63,041)	$	21.65
Outstanding at December 31, 2022	1,191,715	$	35.94	7.47	$	7,673
Granted	2,393,500	$	2.67
Forfeited	(200,849)	$	9.73
Outstanding at December 31, 2023	3,384,366	$	13.97	8.40	$	3,431
Options exercisable at December 31, 2023	1,382,078	$	28.80	6.87
Options vested and expected to vest at December 31, 2023	3,384,366	$	13.97	8.40	$	3,431

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

	Year Ended December 31,
	2023		2022
Expected volatility	90.44	%	82.70	%
Weighted average risk-free interest rate	4.05	%	3.10	%
Expected dividend yield	0.00	%	0.00	%
Expected term (in years)	6.49		6.42

Schedule of RSU activity under the 2016 Plan

		Weighted
	Number of	Average Grant
	Shares	Date Fair Value
Outstanding at December 31, 2021	93,560	$	17.60
Awarded	265,000	$	19.40
Outstanding at December 31, 2022	358,560	$	18.90
Vested	(66,060)	$	14.20
Forfeited	(30,000)	$	19.40
Outstanding at December 31, 2023	262,500	$	19.97

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,
	2023		2022
Research and development	$	2,647	$	2,540
General and administrative		2,481		2,640
Total	$	5,128	$	5,180