Stockholders’ Equity and Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2022

Share-Based Payment Arrangement [Abstract]

Schedule of Warrant Activity

A summary of the Company’s warrant activity during the six months ended June 30, 2022 was as follows:

	Shares of Stock under Warrants	Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term	Aggregate Intrinsic Value
Outstanding at January 1, 2022	4,356,000	$	5.96	1.76	$	785,000
Granted	—	—		—	—
Exercised	—	—		—	—
Canceled	—	—		—	—
Outstanding at June 30, 2022	4,356,000	$	5.96	1.27	$	246,000

Summary of Stock Option Activity

A summary of the Company’s stock option activity during the six months ended June 30, 2022 was as follows:   

	Shares of Stock under Stock Options	Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term	Aggregate Intrinsic Value
Outstanding at January 1, 2022	12,765,000	$	4.97	8.9	$	7,891,000
Granted	12,797,000	2.11		—	—
Exercised	(270,000)	0.59		—	302,000
Canceled	(1,708,000)	5.00		—	—
Outstanding at June 30, 2022	23,584,000	$	3.47	9.08	$	2,053,000
Vested and exercisable at June 30, 2022	4,976,000	$	3.90	7.96	$	1,327,000

Summary of Recognized Stock-Based Compensation Expense

The Company recognized stock-based compensation expense for the periods presented as follows: 

	Three Months Ended June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
Research and development	$	3,468,000	$	384,000	$	6,795,000	$	465,000
General and administrative	2,309,000		1,374,000		4,084,000		1,664,000
Total stock-based compensation expense	$	5,777,000	$	1,758,000	$	10,879,000	$	2,129,000

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

The weighted-average assumptions used in the Black-Scholes option pricing model to determine the fair value of the employee stock option grants during the periods presented were as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
Risk-free interest rate	2.8	%	1.1	%	2.1	%	1.1	%
Expected volatility	70.6	%	80.4	%	70.2	%	80.4	%
Expected term (in years)	5.7		6.0		6.0		6.0
Expected dividend yield	0.0	%	0.0	%	0.0	%	0.0	%

Share-based Payment Arrangement, Restricted Stock Unit, Activity

The following table summarizes restricted share unit (“RSU”) activity during the six months ended June 30, 2022:

	Stock Units	Weighted- Average Grant Date Fair Value per Share
Outstanding at January 1, 2022	361,000	$	4.74
Granted	—	—
Released	(131,000)	4.74
Forfeited	—	—
Outstanding at June 30, 2022	230,000	$	4.74

The following table summarizes performance share unit (“PSU”) activity during the six months ended June 30, 2022:

	Stock Units	Weighted- Average Grant Date Fair Value per Share
Outstanding at January 1, 2021	290,000	$	4.74
Granted	—	—
Released	—	—
Forfeited	—	—
Outstanding at June 30, 2022	290,000	$	4.74