Equity Incentive Plans (Tables)

3 Months Ended

Mar. 31, 2023

Equity Incentive Plans

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, 2022	11,917,331	3.59	7.47	—
Granted	8,235,000	0.34
Forfeited	(64,173)	1.90
Outstanding at March 31, 2023	20,088,158	2.27	8.33	—
Options exercisable at March 31, 2023	8,247,158	4.49	6.35	—
Options vested and expected to vest at March 31, 2023	20,088,158	2.27	8.33	—

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

	Three Months		Three Months
	Ended March 31,		Ended March 31,
	2023		2022
Expected volatility	89.99	%	82.70	%
Weighted average risk-free interest rate	3.56	%	1.67	%
Expected dividend yield	0.00	%	0.00	%
Expected term (in years)	6.42		6.01

Schedule of RSU activity under the 2016 Plan

		Weighted
		Average Grant
	Number of Shares	Date Fair Value
Outstanding at December 31, 2022	3,585,606	$	1.89
Vested	(660,606)	$	1.42
Outstanding at March 31, 2023	2,925,000	$	2.00

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

	Three Months Ended March 31,
	2023		2022
Research and development	$	704	$	554
General and administrative		606		650
Total	$	1,310	$	1,204