Stock-based awards (Tables)

6 Months Ended

Jun. 30, 2022

Share-Based Payment Arrangement [Abstract]

Schedule of assumptions used to determine grant-date fair value of stock options granted

The assumptions that the Company used to determine the grant-date fair value of stock options granted to employees, directors and consultants as follows, presented on a weighted average basis:

	Three Months Ended June 30,						Six Months Ended June 30,
	2022			2021			2022			2021
Expected term (in years)		5.75			5.66			5.77			5.86
Expected volatility		74.24	%		70.43	%		73.10	%		70.43	%
Weighted average risk-free interest rate	2.91		%	1.05		%		1.82	%		0.80	%
Expected dividend yield		0.00	%		0.00	%		0.00	%		0.00	%

Summary of stock option activity

The following table summarizes the Company’s stock option activity since December 31, 2021:

				Weighted-		Weighted-
				Average		Average		Aggregate
				Exercise		remaining		Intrinsic
	Number			Price per		contractual		Value
	of Options			Share		term (years)		(000's)
Balance outstanding, December 31, 2021		5,221,094		$	15.49		8.20		36,168
Options granted		703,527		$	18.10
Options exercised		(122,208	)	$	1.21
Options cancelled		(31,055	)	$	22.16
Balance outstanding, June 30, 2022		5,771,358		$	16.07		7.87	$	10,986
Vested and expected to vest, June 30, 2022		5,189,977		$	15.49		7.75	$	10,986
Exercisable, June 30, 2022		2,719,542		$	11.91		7.08	$	9,145

Summary of stock-based compensation expense

The following table summarizes the Company’s stock-based compensation expense during the three and six months ended June 30, 2022 and 2021:

	Three Months Ended June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
Classified within research and development expense	$	1,474	$	734	$	2,585	$	1,453
Classified within general and administrative expense		2,687		1,702		4,887		3,347
Total stock-based compensation expense	$	4,161	$	2,436	$	7,472	$	4,800