Equity-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2020

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 June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
	(In thousands)
Research and development	$	2,390	$	2,096	$	4,550	$	3,879
General and administrative		2,374		2,308		4,371		5,117
Total	$	4,764	$	4,404	$	8,921	$	8,996

Summary of Restricted Stock Activity

The following table summarizes the Company’s restricted stock activity for the six months ended June 30, 2020:

	Number of Shares			Weighted Average Grant Date Fair Value per Share
Unvested restricted stock as of December 31, 2019		71,875		$	22.88
Granted		181,020			15.05
Vested		-			-
Cancelled		(4,410	)		15.05
Unvested restricted stock as of June 30, 2020		248,485		$	17.31

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

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

	Three Months Ended June 30,		Six Months Ended June 30,
	2020	2019	2020	2019
Risk-free interest rate	0.4%	2.1%	0.9%	2.4%
Expected life of options	5.5-6.0 years	5.5-6.0 years	5.5-6.0 years	5.5-6.0 years
Expected volatility of underlying stock	70.2%	67.9%	67.3%	68.6%
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, 2020

	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, 2019		5,365,971		$	15.67
Granted		2,586,815			13.59
Exercised		(137,210	)		9.99
Forfeited		(234,536	)		16.82
Outstanding at June 30, 2020		7,581,040		$	15.03		8.18	$	49,006
Exercisable at June 30, 2020		3,114,690		$	14.63		6.85	$	22,023