Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2022

Summary of Stock-based Compensation Expense Recognized

During the three months ended March 31, 2022 and 2021, the Company recognized the following stock-based compensation expense (in thousands):

	Three Months Ended March 31,
	2022		2021
Stock-based compensation expense by type of award:
Stock options	$	1,026	$	826
Restricted stock and restricted stock units		1,287		687
Employee stock purchase plan		44		64
Total stock-based compensation expense included    in expenses	$	2,357	$	1,577
Stock-based compensation expense by line item:
Research and development expenses	$	664	$	435
General and administrative expenses		1,693		1,142
Total stock-based compensation expense included    in expenses	$	2,357	$	1,577

Schedule of Unrecognized Stock-based Compensation Expense, Net of Estimated Forfeitures, by Type of Award and Weighted-average Recognition Period

The following table sets forth the Company’s unrecognized stock-based compensation expense, net of estimated forfeitures, by type of award and the weighted-average period over which that expense is expected to be recognized (in thousands, except for years):

	As of March 31, 2022
	Unrecognized Expense, Net of Estimated Forfeitures		Weighted- average Recognition Period (in years)
Type of award:
Stock options	$	7,642		2.68
Restricted stock and restricted stock units	$	5,821		1.55

Summary of Stock Option Activity

The following table summarizes stock option activity during the three months ended March 31, 2022:

	Shares Subject to Stock Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value
Options outstanding at December 31, 2021		4,088,084		$	5.63
Granted		1,005,023		$	4.80
Exercised		—		$	—
Forfeited		(15,000	)	$	6.61
Cancelled		(5,000	)	$	6.61
Options outstanding at March 31, 2022		5,073,107		$	5.46		7.36		1,373,000
Options exercisable at March 31, 2022		2,873,185		$	5.26		6.07		1,373,000

Schedule of Weighted Average Assumptions using Black-Scholes Option Pricing Model

the fair value of each employee option grant during the three months ended March 31, 2022 was estimated on the date of grant using the Black-Scholes model with the following weighted average assumptions:

	Three Months Ended March 31, 2022
Expected volatility		87.31	%
Expected term (in years)		6.15
Risk-free interest rate		1.50	%
Expected dividend yield		0	%

Restricted stock [Member]

Summary of Shares Granted and Stock Activity

The following table is a summary of restricted stock activity during the three months ended March 31, 2022:

	Shares of Restricted Stock		Weighted- Average Grant Date Fair Value
Unvested at December 31, 2021		183,095	$	0.17
Granted		—	$	—
Vested		—	$	—
Forfeited		—	$	—
Unvested at March 31, 2022		183,095	$	0.17

Restricted stock units [Member]

Summary of Shares Granted and Stock Activity

The following table summarizes restricted stock unit activity during the three months ended March 31, 2022:

	Shares Subject to Restricted Stock Units			Weighted- Average Grant Date Value
Unvested at December 31, 2021		962,299		$	6.63
Granted		1,030,786		$	4.88
Vested		(222,503	)	$	6.70
Forfeited		—		$	—
Unvested at March 31, 2022		1,770,582		$	5.60