Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2022

The following table summarizes stock option activity under the Company’s stock-based compensation plan during the three months ended March 31, 2022 (in thousands, except option and share data):

	Shares Available for Grant			Number of Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Life (in Years)		Aggregate Intrinsic Value
Outstanding as of December 31, 2021		1,327,645			5,262,185		$	10.24		7.25	$	530
Additional shares authorized		1,728,441			—
Granted		(1,353,300	)		1,353,300		$	5.17
Restricted stock units granted		(298,150	)		—
Exercised		—			(15,995	)	$	8.98
Forfeited or cancelled		109,039			(109,039	)	$	12.06
Restricted stock units forfeited		33,225			—
Outstanding as of March 31, 2022		1,546,900			6,490,451		$	9.16		7.75	$	7,636
Vested and exercisable as of March 31, 2022					3,115,184		$	11.07		6.22	$	1,934

Summary of Non-cash Stock Based Compensation Expense

Total stock-based compensation expense recognized was as follows (in thousands):

	Three Months Ended March 31,
	2022		2021
Research and development	$	625	$	391
Selling, general and administrative		1,422		1,158
Total	$	2,047	$	1,549

Employees and Non Employees Stock Option [Member]

Weighted-average assumptions used in Black-Scholes Model to estimate fair value of stock options granted

The fair value of stock options was estimated using the following weighted-average assumptions:

	Three Months Ended March 31,
	2022	2021
Expected term (in years)	5.27-6.08	5.27-6.08
Volatility	68.71%-70.75%	72.39%-100.87%
Risk free interest rate	1.76%-2.41%	0.62%-1.16%
Dividend yield	—	—

Restricted Stock Units (RSU) [Member]

Schedule of Nonvested Restricted Stock Units Activity and Weighted Average Grant Date Fair Value

The following table summarizes RSU and PSU activity and weighted average grant date fair value for the three months ended March 31, 2022:

	Shares			Weighted- Average Grant Date Fair Value
Unvested shares as of December 31, 2021		623,000		$	8.63
Granted		298,150		$	5.22
Vested		(85,106	)	$	10.09
Forfeited		(33,225	)	$	8.33
Unvested shares as of March 31, 2022		802,819		$	7.22