Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2022

Share-based Payment Arrangement [Abstract]

Schedule of Stock-Based Compensation Expense

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

	Three Months Ended June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
	(In thousands)				(In thousands)
Research and development	$	1,417	$	2,023	$	3,209	$	4,253
General and administrative		3,034		4,695		6,531		9,480
Total	$	4,451	$	6,718	$	9,740	$	13,733

Assumptions Used in Applying Pricing Model

Key assumptions used to apply this pricing model were as follows:

	Three Months Ended June 30,						Six Months Ended June 30,
	2022			2021			2022			2021
Risk-free interest rate		2.7	%		0.8	%		2.2	%		0.5	%
Expected life of options	5.87 years			5.71 years			5.94 years			5.94 years
Expected volatility of underlying stock		74.2	%		70.7	%		73.1	%		70.5	%
Expected dividend yield		0.0	%		0.0	%		0.0	%		0.0	%

Summary of Stock Option Activity

The following is a summary of stock option activity for the six months ended June 30, 2022:

	Number of Options			Weighted Average Exercise Price per Share		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
	(In thousands)					(In years)		(In thousands)
Outstanding at December 31, 2021		12,946		$	11.61
Granted		5,681			1.29
Exercised		—			—
Forfeited		(3,204	)		11.26
Outstanding at June 30, 2022		15,423		$	7.87		8.06	$	1,073
Exercisable at June 30, 2022		5,525		$	13.85		5.95	$	—

Summary of Service Based Restricted Stock Units

During the six months ended June 30, 2022, 87,500 RSUs were granted to an executive (the “executive RSUs”) and 80,946 RSUs were granted to non-employee directors (the “non-employee RSUs”). RSUs vest based on continuing service to the Company. Assuming all service conditions are achieved, the executive RSUs will vest in three equal installments with the first installment vesting approximately six and a half months following the grant date and the second and third installments vesting annually thereafter, and the non-employee director RSUs will vest as to 100% of the RSUs on the earlier of the first anniversary of the grant date and the date of the succeeding annual meeting of stockholders.

	Number of Service Based RSU Shares (in thousands)			Weighted Average Grant Date Fair Value
Outstanding at December 31, 2021		2,222		$	8.70
Granted		169			1.00
Vested		(361	)		12.57
Forfeited		(537	)		7.62
Outstanding at June 30, 2022		1,493		$	7.28