Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Stock Based Compensation Expense Recognized

Stock-based compensation expense is recognized in the condensed consolidated statements of operations as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2021		2020		2021		2020
	(in thousands)
Research and development	$	4,072	$	980	$	9,888	$	2,555
General and administrative		1,878		186		5,161		482
Total stock-based compensation expense	$	5,950	$	1,166	$	15,049	$	3,037

Schedule of Unrecognized Stock-Based Compensation Costs Related to Unvested Awards and Weighted-Average Period Over Which Costs are Expected to be Recognized

Unrecognized stock-based compensation costs related to unvested awards and the weighted-average period over which the costs are expected to be recognized as of September 30, 2021 are as follows:

	Stock Options		RSAs		RSUs
Unrecognized stock-based compensation expense (in thousands)	$	79,637	$	2,166	$	887
Weighted-average period costs expected to be recognized (years)		2.8		1.1		1.5

Summary of Stock Option Activity

A summary of the Company’s stock option activity is as follows:

	Stock Options (in thousands)			Weighted- Average Exercise Price per Share		Weighted-Average Remaining Contractual Life (years)		Aggregate Intrinsic Value (in thousands)
Outstanding as of December 31, 2020		15,677		$	4.52
Granted		3,398			23.26
Exercised		(1,121	)		1.99
Forfeited/Cancelled		(671	)		5.05
Outstanding as of September 30, 2021		17,283		$	8.34		8.9	$	244,590
Exercisable as of September 30, 2021		2,874		$	2.05		8.2	$	58,832

Schedule of Assumptions Used in Black-Scholes Option-Pricing Model for Estimating Fair Value of Stock Options Granted

The fair value of stock options granted to employees, directors, and consultants was estimated on the date of grant using the Black-Scholes option pricing model using the following assumptions:

	Nine Months Ended September 30,
Assumptions	2021			2020
Risk free interest rate	0.46% - 1.15%			0.36% - 1.51%
Expected volatility		70	%		70	%
Expected term (years)	5.50 - 6.40			6.25 - 6.75
Expected dividend		0	%		0	%

Summary of Additional Information Related to Stock Option Activity

The following table summarizes additional information related to stock option activity:

	Nine Months Ended September 30,
	2021		2020
Weighted average grant date fair value per share for options granted	$	14.64	$	0.54
Aggregate intrinsic value of stock options exercised (in thousands)	$	22,187	$	205

Summary of RSA Activity

A summary of the Company’s RSA activity is as follows:

	RSAs (in thousands)			Weighted-Average Grant Date Fair Value per Share
Unvested shares as of December 31, 2020		10,079		$	0.33
Vested		(4,273	)		0.25
Forfeited		(15	)		0.73
Unvested shares as of September 30, 2021		5,791		$	0.39