Equity Incentive Plans (Tables)

3 Months Ended

Mar. 31, 2023

Share-Based Payment Arrangement [Abstract]

Summary of Company's stock option activity

Activity under the Company’s stock option plans during the three months ended March 31, 2023 was as follows:

				Weighted-		Weighted-		Aggregate
				Average		Average		Intrinsic
	Options			Exercise		Remaining		Value
	Outstanding			Price		Term		(000’s)
Balance at December 31, 2022		9,757,329		$	17.79
Granted		2,171,590		$	19.27
Exercised		(31,810	)	$	15.21
Forfeited and expired		(359,995	)	$	21.73
Balance at March 31, 2023		11,537,114		$	17.95		8.2	$	14,260
Vested and expected to vest at March 31, 2023		11,537,114		$	17.95		8.2	$	14,260
Exercisable at March 31, 2023		4,514,770		$	16.24		6.8	$	13,495

Summary of Company's restricted stock unit activity

The Company’s restricted stock unit activity during the three months ended March 31, 2023 was as follows:

				Weighted-
	Restricted Stock			Average
	Units			Grant Date
	Outstanding			Fair Value
Balance at December 31, 2022		290,311		$	19.88
Granted		604,621		$	19.64
Vested		(81,294	)	$	19.54
Forfeited		(7,238	)	$	19.84
Balance at March 31, 2023		806,400		$	19.74

Weighted Average Assumptions Used to Estimate Fair Value of Stock Awards Granted to Employees

The following table summarizes the weighted average assumptions used to estimate the fair value of stock options granted under the Company’s stock option plans for the periods presented below:

Stock Option Awards	Three months ended March 31,
	2023	2022
Expected option term	6.0 years	6.0 years
Expected volatility	67%	88%
Risk free interest rate	4.2%	1.8%
Expected dividend yield	—%	—%

Summary of Stock-based Compensation Expense for the Equity Awards Issued to Employees and Non-Employees

Stock-based compensation expense for the equity awards issued by the Company to employees and non-employees for the periods presented below was as follows (in thousands):

	Three months ended March 31,
	2023		2022
Included in research and development	$	4,678	$	3,191
Included in general and administrative		3,418		2,564
Total stock-based compensation expense	$	8,096	$	5,755