Stock-based compensation (Tables)

12 Months Ended

Dec. 31, 2022

Share-Based Payment Arrangement [Abstract]

Summary of Stock Based Compensation Expense

Stock-based compensation expense recorded in the consolidated statements of operations and comprehensive loss is as follows:

	Year ended December 31,
(in thousands)	2022		2021		2020
Research and development	$	12,486	$	3,830	$	494
General and administrative		9,991		3,242		356
Total stock-based compensation expense	$	22,477	$	7,072	$	850

Schedule of Assumptions Used for Options Granted

The assumptions used in Black-Scholes for stock options granted were as follows:

	Year ended December 31,
	2022			2021			2020
Expected volatility		77.3	%		77.7	%		84.8	%
Weighted-average risk-free interest rate		2.4	%		0.9	%		0.4	%
Expected dividend yield		—			—			—
Expected term (in years)		6.0			6.0			6.0

Schedule of Stock Option Activity

The following table provides a summary of stock option activity during the year ended December 31, 2022:

	Number of options			Weighted average exercise price per share		Weighted average remaining contractual life (in years)		Aggregate intrinsic value(2) (in thousands)
Outstanding at December 31, 2021		6,119,295		$	9.44
Granted		2,561,300		$	28.49
Exercised		(743,638	)	$	2.92
Forfeited		(324,131	)	$	20.37
Outstanding at December 31, 2022		7,612,826		$	16.10		8.3	$	63,790
Exercisable at December 31, 2022		2,551,841		$	7.52		7.6	$	34,295
Expected to vest after December 31, 2022(1)		5,060,985		$	20.43		8.6	$	29,495

(1)This represents the number of unvested options outstanding as of December 31, 2022 that are expected to vest in the future.

(2)The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying options and the estimated fair value of the common stock for the options that were in the money as of December 31, 2022.

Schedule of Status and Change in Unvested Restricted Stock and Restricted Stock Units

A summary of the status of and change in unvested restricted stock units as of December 31, 2022 was as follows:

	Shares				Weighted- average grant date fair value per share
Unvested restricted stock units as of December 31, 2021		32,000		$		36.58
Restricted stock units granted		688,700		$		22.65
Restricted stock units vested		(6,375	)	$		35.53
Restricted stock units forfeited		(36,500	)	$		24.32
Unvested restricted stock units as of December 31, 2022		677,825		$		23.10