Equity Incentive Plans and Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2021

Share-based Payment Arrangement [Abstract]

Summary of Option Activity

The following table summarizes the option activity for the year ended December 31, 2021:

	Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2020		3,996,174		$	9.03
Granted		1,694,692			26.55
Exercised		(160,303	)		6.26
Forfeited and cancelled		(262,243	)		21.02
Outstanding at December 31, 2021		5,268,320		$	14.16		7.9	$	25,633
Exercisable at December 31, 2021		2,317,374		$	6.76		7.1	$	19,965

Summary of Fair Value of Stock Options Estimated Using Black-Scholes Merton Option Pricing Model Assumptions

The fair value of stock option awards to employees, executives, directors, and other service providers was estimated at the date of grant using the Black-Scholes Merton option pricing model with the following assumptions.

	Years Ended December 31,
	2021	2020	2019
Stock price	$13.36 - $35.67	$16.00 - $35.92	$1.60 - $9.16
Risk-free interest rate	0.60% - 1.34%	3.17% - 5.59%	1.4% - 2.6%
Expected volatility	82.34% - 88.43%	88.01% - 95.11%	77% - 104%
Expected term (in years)	5.50 - 6.08	5.50 - 6.08		6.10
Expected dividend yield	0%	0%	0%

Summary of Total Stock-based Compensation Expense

The table below summarizes the total stock-based compensation expense included in the Company’s statements of operations and comprehensive loss for stock options for the periods presented (in thousands):

	Years Ended December 31,
	2021		2020		2019
Research and development	$	4,959	$	2,025	$	476
General and administrative		7,894		3,253		618
Total stock-based compensation expense	$	12,853	$	5,278	$	1,094