Equity (Tables)

3 Months Ended

Mar. 31, 2022

Equity [Abstract]

Summary of Stock-based Compensation Expense

Stock-based compensation expense is classified in the condensed statements of operations as follows:

(in thousands)	Three Months Ended March 31,
	2022		2021
Research and development expenses	$	1,264	$	1,018
General and administrative expenses	1,182		1,402
Total stock-based compensation expense	$	2,446	$	2,420

Schedule of Weighted Average Assumptions

The fair values of stock options granted are estimated using the Black-Scholes option pricing model with the following weighted average assumptions:

	Three Months Ended March 31,
	2022		2021
Expected volatility	83.18	%	89.68	%
Expected dividends	0	%	0	%
Expected terms (years)	6.07		6.06
Risk free rate	1.95	%	0.61	%

Schedule of Stock Option Activity

A summary of the Company’s stock option activity and related information for the three months ended March 31, 2022 is as follows:

	Number of Shares	Weighted Average Exercise Price		Weighted Average Remaining Contractual Life  (in Years)	Aggregate Intrinsic Value (in Thousands)
Outstanding at December 31, 2021	8,963,945	$	7.20	8.32	$	6,912
Options granted	715,500	$	2.46
Options exercised	(36,500)	$	3.67
Options cancelled/forfeited	(1,345,024)	$	8.52
Outstanding at March 31, 2022	8,297,921	$	6.60	8.27	$	28
Exercisable as of March 31, 2022	3,341,197	$	5.71	7.38	$	—

Summary of RSU Activity

A summary of the Company’s RSU activity and related information for the three months ended March 31, 2022 is as follows:

	Number of Shares	Weighted Average Grant Date Fair Value
Non-vested at December 31, 2021	132,000	$	9.97
Restricted stock units granted	700,000	$	3.69
Restricted stock units vested	—	$	—
Restricted stock units forfeited	(122,000)	$	4.95
Non-vested at March 31, 2022	710,000	$	4.64