Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Stock Based Compensation Expense Recognized

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

	Year Ended December 31,
	2021		2020		2019
	(in thousands)
Research and development	$	15,239	$	4,888	$	1,246
General and administrative		7,123		940		251
Total stock-based compensation expense	$	22,362	$	5,828	$	1,497

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 December 31, 2021 are as follows:

	Stock Options		RSAs		RSUs
Unrecognized stock-based compensation expense (in thousands)	$	81,140	$	1,892	$	1,220
Weighted-average period costs expected to be recognized (in years)		3.2		1.5		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 (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding as of December 31, 2020		15,677		$	4.52
Granted		4,165			22.57
Exercised		(1,586	)		2.00
Forfeited/Cancelled		(919	)		6.88
Outstanding as of December 31, 2021		17,337		$	8.96		8.7	$	141,718
Exercisable as of December 31, 2021		3,215		$	2.61		8.1	$	41,382

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:

	Year Ended December 31,
Assumptions	2021	2020	2019
Risk free interest rate	0.46% - 1.38%	0.36% - 1.51%	1.53% - 2.62%
Expected volatility	70%	70%	70%
Expected term (years)	5.50 - 6.40	6.25 - 6.75	6.02 - 6.25
Expected dividend	0%	0%	0%

Summary of Additional Information Related to Stock Option Activity

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

	Year Ended December 31,
	2021		2020		2019
Weighted average grant date fair value per share for options granted	$	14.22	$	3.52	$	0.92
Aggregate intrinsic value of stock options exercised (in thousands)	$	29,880	$	605	$	25

Summary of RSA Activity

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

	RSAs (in thousands)			RSAs Weighted-Average Grant Date Fair Value per Share		RSUs (in thousands)			RSUs Weighted-Average Grant Date Fair Value per Share
Unvested shares as of December 31, 2020		10,079		$	0.33		326		$	1.44
Granted		-			-		57			21.37
Vested		(5,691	)		0.25		(225	)		1.44
Forfeited		(23	)		1.00		(17	)		1.44
Unvested shares as of December 31, 2021		4,365		$	0.43		141		$	9.43