Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2022

Share-Based Payment Arrangement [Abstract]

Summary of Stock Option Activity

The summary of stock option activity for the six months ended June 30, 2022 (in thousands, except share and per share amounts):

	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value
Outstanding at January 1, 2022		5,926,969		$	10.03		9.5	$	16,414
Granted		527,277			6.24
Exercised		(64,838	)		2.73
Forfeited		(603,044	)		7.52
Expired		(33,838	)		5.34
Outstanding at June 30, 2022		5,752,526		$	10.08		9.1	$	144
Options exercisable at June 30, 2022		1,338,597		$	6.00		8.8	$	80

Schedule of Estimated Fair Value Assumptions

The Company estimated the fair value of each option on the date of grant using the Black-Scholes option pricing model applying the range of assumptions in the following table:

	Three Months Ended June 30,		Six Months Ended June 30,
	2022	2021	2022	2021
Expected volatility	101.14% - 101.63%	74.93%	98.05% - 101.66%	77.00%
Risk-free interest rate	2.53% - 3.34%	1.05%	1.6% - 3.34%	1.05% - 1.16%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Expected term (in years)	6.08 - 6.11	6.08	6.08 - 6.11	6.02 - 6.08

Summary of Stock-Based Compensation Expense

Stock-based compensation expense related to stock options recorded is as follows (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
Research and development	$	1,095	$	190	$	1,567	$	1,010
General and administrative		1,726		363		4,600		1,987
Total	$	2,821	$	553	$	6,167	$	2,997

Summary of Restricted Stock Activity

The summary of restricted stock activity for the six months ended June 30, 2022:

	Number of Shares			Weighted Average Grant Date Fair Value
Non-vested at December 31, 2021		618,494		$	3.04
Granted		2,818,467			3.90
Vested		(196,164	)		0.05
Forfeited		(279,817	)		3.58
Non-vested at June 30, 2022		2,960,980		$	3.64