Stock-Based Compensation (Tables)

6 Months Ended

Jun. 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 June 30,				Six Months Ended June 30,
	2021		2020		2021		2020
	(in thousands)
Research and development	$	3,148	$	927	$	5,816	$	1,575
General and administrative		1,793		189		3,283		296
Total stock-based compensation expense	$	4,941	$	1,116	$	9,099	$	1,871

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 June 30, 2021 are as follows:

	Stock Options		RSAs		RSUs
Unrecognized stock-based compensation expense (in thousands)	$	59,901	$	2,520	$	258
Weighted-average period costs expected to be recognized (years)		3.1		1.3		1.7

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		1,558			24.43
Exercised		(417	)		1.58
Forfeited/Cancelled		(376	)		3.67
Outstanding as of June 30, 2021		16,442		$	6.42		9.0	$	216,379
Exercisable as of June 30, 2021		2,698		$	1.52		8.3	$	48,928

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:

	Six Months Ended June 30,
Assumptions	2021			2020
Risk free interest rate	0.46%-1.14%			0.41%-1.51%
Expected volatility		70.00	%		70.00	%
Expected term (years)	5.50 - 6.25			6.25-6.75
Expected dividend		0.00	%		0.00	%

Summary of Additional Information Related to Stock Option Activity

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

	Six Months Ended June 30,
	2021		2020
Weighted average grant date fair value per share for options granted	$	15.30	$	1.21
Aggregate intrinsic value of stock options exercised (in thousands)	$	9,464	$	23

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		(2,851	)		0.25
Forfeited		(15	)		0.73
Unvested shares as of June 30, 2021		7,213		$	0.36