Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2022

Share-Based Payment Arrangement [Abstract]

Summary of Assumptions that Used to Determine Grant-Date Fair Value of Stock Options Granted to Employees and Members of Board of Directors

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

	Nine Months Ended September 30,
	2022			2021
Expected option life (years)		5.96			6.07
Risk-free interest rate		1.80	%		0.76	%
Expected volatility		80.22	%		81.25	%
Expected dividend yield		—	%		—	%

Summary of Stock Option Activity

The following table summarizes the Company’s stock option activity for the nine months ended September 30, 2022:

	Number of Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value
Outstanding as of December 31, 2021		7,423,777		$	13.54		6.79	$	1,469
Granted		3,455,157		$	1.79
Exercised		—		$	—
Cancelled or forfeited		(2,795,571	)	$	11.99
Outstanding as of September 30, 2022		8,083,363		$	9.05		7.69	$	50
Exercisable as of September 30, 2022		3,266,645		$	12.69		5.87	$	50

Summary of Restricted Common Stock Units

The following table summarizes the Company’s restricted common stock units for the nine months ended September 30, 2022:

	Number of Shares			Weighted- Average Grant Date Fair Value
Issued and unvested as of December 31, 2021		599,850		$	9.64
Granted		850,168		$	1.62
Vested		(431	)	$	15.65
Forfeited, cancelled or expired		(579,051	)	$	6.56
Issued and unvested as of September 30, 2022		870,536		$	3.85

Schedule of Stock-based Compensation Expense

Stock-based compensation expense was allocated as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2022		2021		2022		2021
Research and development	$	448	$	1,965	$	2,169	$	5,989
General and administrative		2,208		3,204		7,098		8,505
Total stock-based compensation expense	$	2,656	$	5,169	$	9,267	$	14,494