Share-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2022

Share-Based Payment Arrangement [Abstract]

Schedule of Outstanding Stock Options

Total outstanding stock options as of September 30, 2022 was as follows:

	2022
	Number of shares			Weighted average exercise price
Outstanding at beginning of period		5,322,591		$	14.76
Granted		3,213,667		$	14.29
Exercised		(73,433	)	$	3.85
Cancelled or forfeited		(399,648	)	$	20.78
Outstanding at end of period		8,063,177		$	14.37

Schedule of Fair Value of Stock Options Determined on Grant Date Using Black Scholes Option-Pricing Model

The fair value of stock options, and the assumptions used in the Black Scholes option-pricing model to determine the grant date fair value of stock options granted to employees and non-employees were as follows, presented on a weighted average basis:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2022			2021			2022			2021
Fair value of stock options	$	8.45		$	21.99		$	9.40		$	23.29
Risk-free interest rate		2.89	%		0.98	%		2.09	%		0.73	%
Expected terms (in years)		6.08			5.85			5.98			5.99
Expected volatility		81.20	%		76.10	%		78.82	%		75.61	%
Expected dividend yield		0.00	%		0.00	%		0.00	%		0.00	%

Schedule of Share-based Compensation Expense

Share-based compensation expense was allocated as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2022		2021		2022		2021
	(in thousands)
Research and development	$	2,600	$	1,557	$	7,351	$	3,985
General and administrative		2,453		2,136		7,202		4,948
Total share-based compensation expense	$	5,053	$	3,693	$	14,553	$	8,933

Share-based compensation expense by type of award was as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2022		2021		2022		2021
	(in thousands)
Stock options	$	4,969	$	3,636	$	14,376	$	8,784
ESPP		84		57		177		149
Total share-based compensation expense	$	5,053	$	3,693	$	14,553	$	8,933