Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2022

Share-Based Payment Arrangement [Abstract]

Summary of Recognized Stock-Based Compensation

The Company recognized stock-based compensation as follows:

	Year Ended December 31,
	2022		2021		2020
	(In thousands)
Research and development	$	24,895	$	21,443	$	14,980
General and administrative		21,251		19,342		15,542
Total stock-based compensation	$	46,146	$	40,785	$	30,522

Summary of Share-based Payment Award, Stock Options, Valuation Assumptions

The estimated grant-date fair value of all the Company’s options to purchase common stock was calculated using the Black-Scholes option pricing model, based on the following assumptions:

	Year Ended December 31,
	2022	2021	2020
Expected term (in years)	5.3– 6.1	5.2 – 6.1	5.3 – 6.1
Expected volatility	79% – 80%	78% – 81%	74% – 78%
Risk free interest rate	1.5% – 4.3%	0.5% – 1.3%	0.3% – 1.8%
Dividend yield	—	—	—

Summary of Options to Purchase Common Stock

Option activity is shown below:

	Number of Options			Weighted Average Exercise Price Per Share		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
						(In years)		(In thousands)
Outstanding as of December 31, 2020		12,654,998		$	13.96
Granted		3,264,059			21.53
Exercised		(2,395,223	)		11.91
Forfeited		(1,879,764	)		14.55
Outstanding as of December 31, 2021		11,644,070			16.41
Granted		4,996,366			12.11
Exercised		(298,239	)		10.26
Forfeited		(2,628,925	)		18.28
Outstanding as of December 31, 2022		13,713,272		$	14.62		8.0	$	1,583
Exercisable as of December 31, 2022		6,776,201		$	14.75		7.0	$	1,276
Vested and expected to vest as of December 31,    2022		13,713,272		$	14.62		8.0	$	1,583

Summary of Restricted Stock Awards and Restricted Stock Units

Activity for the restricted stock awards and RSUs is shown below.

	Number of Shares			Weighted Average Grant Date Fair Value per Share
Unvested restricted stock awards and restricted stock units as of December 31, 2020		186,425		$	6.95
Granted		1,822,295			17.33
Vested		(324,802	)		10.35
Forfeited		(310,044	)		13.85
Unvested restricted stock units as of December 31, 2021		1,373,874			18.35
Granted		2,539,014			10.02
Vested		(414,577	)		18.63
Forfeited		(453,693	)		16.21
Unvested restricted stock units as of    December 31, 2022		3,044,618		$	11.68