Equity-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Equity-Based Compensation Expense

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

	Three Months Ended March 31,
	2021		2020
	(In thousands)
Research and development	$	3,491	$	2,160
General and administrative		2,933		1,997
Total	$	6,424	$	4,157

Summary of Restricted Stock Activity

The following table summarizes the Company’s restricted stock activity for the three months ended March 31, 2021:

	Number of Shares			Weighted Average Grant Date Fair Value per Share
Unvested restricted stock as of December 31, 2020		193,936		$	23.98
Granted		259,839			57.71
Vested		-			-
Cancelled		(11,035	)		27.59
Unvested restricted stock as of March 31, 2021		442,740		$	43.69

Summary of Weighted Average Assumptions Used to Compute Fair Value of Option Granted

Weighted average assumptions used to apply this pricing model were as follows:

	Three Months Ended March 31,
	2021	2020
Risk-free interest rate	0.9%	1.0%
Expected life of options	6.0 years	6.0 years
Expected volatility of underlying stock	72.0%	66.7%
Expected dividend yield	0.0%	0.0%

Summary of Stock Option Activity

The following is a summary of stock option activity for the three months ended March 31, 2021: 

	Number of Options			Weighted Average Exercise Price per Share		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
						(In years)		(In thousands)
Outstanding at December 31, 2020		6,977,440		$	15.43
Granted		1,645,823			57.94
Exercised		(1,014,569	)		13.15
Forfeited		(129,393	)		20.71
Outstanding at March 31, 2021		7,479,301		$	25.00		8.25	$	413,258
Exercisable at March 31, 2021		2,734,966