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Stock-based Compensation (Tables)

3 Months Ended

Mar. 31, 2022

Share-based Payment Arrangement [Abstract]

Summary of Stock Option Activity

A summary of the Company’s stock option activity under the 2021 Plan and 2018 Plan is as follows (in thousands, except share and per share data and years):

										Weighted-
						Weighted-				average remaining				Aggregate
						average				contractual				intrinsic
		Shares				exercise price				term (years)				value
Outstanding at December 31, 2021			13,818,212			$	3.87				8.82			$	163,264
Granted			4,272,046				11.59
Exercised			(357,244	)			1.29
Canceled			(420,311	)			5.11
Outstanding at March 31, 2022			17,312,703			$	5.79				8.88			$	67,194
Options exercisable at March 31, 2022			4,201,565			$	2.24				8.18			$	26,979

Assumptions used to Determine Fair Value of Stock Option Grants

The assumptions used in the Black-Scholes option pricing model to determine the fair value of the employee and nonemployee stock option grants were as follows:

		Three Months Ended March 31,
		2022		2021
Risk-free interest rate		1.46%-1.74%		0.59%-1.01%
Expected volatility		85.86%-85.99%		83.4%-83.9%
Expected term (in years)		5.99-6.08		6.08
Expected dividend yield		--%		--%

Summary of Restricted Stock Activity

The summary of the Company’s restricted stock activity during the three months ended March 31, 2022 is as follows:

		Number of				Weighted-
		restricted				average
		stock shares				grant date
		outstanding				fair value
Nonvested at December 31, 2021			212,941			$	0.001
Vested			(86,198	)			0.001
Forfeited			(6,945	)			0.001
Nonvested at March 31, 2022			119,798			$	0.001

Schedule of Stock-based Compensation Expense

The allocation of stock-based compensation for all stock awards was as follows (in thousands):

		Three Months Ended March 31,
		2022				2021
Research and development		$	2,732			$	491
General and administrative			1,710				304
Total		$	4,442			$	795

Summary of Common Stock Reserved for Future Issuance

Common stock reserved for future issuance consisted of the following as of March 31, 2022 and December 31, 2021:

		March 31,				December 31,
		2022				2021
Stock options issued and outstanding			17,312,703				13,818,212
Awards available for future grant			16,923,767				14,699,430
Shares available for purchase under the ESPP			1,168,013				1,168,013
Total			35,404,483				29,685,655

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Common stock reserved for future issuance.

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Tabular disclosure of allocation of amount expensed and capitalized for award under share-based payment arrangement to statement of income or comprehensive income and statement of financial position. Includes, but is not limited to, corresponding line item in financial statement.

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Tabular disclosure of the number and weighted-average grant date fair value for restricted stock units that were outstanding at the beginning and end of the year, and the number of restricted stock units that were granted, vested, or forfeited during the year.

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Tabular disclosure for stock option plans. Includes, but is not limited to, outstanding awards at beginning and end of year, grants, exercises, forfeitures, and weighted-average grant date fair value.

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