Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2022

Stock-Based Compensation

Summary of common stock reserved for future issuance

As of September 30, 2022, the Company had reserved shares of its common stock for future issuance as follows:

	Shares Reserved
Common stock options outstanding		4,470,120
Unvested restricted stock units		309,500
Available for future grants under the 2021 Equity Incentive Plan		1,977,969
Available for future grants under the 2021 Employee Stock Purchase Plan		457,916
Total shares of common stock reserved		7,215,505

Summary of the Company's stock option activity

A summary of the Company’s stock option activity and related information during the nine months ended September 30, 2022 is as follows:

	Options Outstanding			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2021		4,215,643		$	5.49		8.5	$	13,530
Granted		555,576			4.36
Exercised		(50,712	)		1.99
Forfeited/Expired		(250,387	)		6.09
Outstanding at September 30, 2022		4,470,120		$	5.36		7.7	$	729
Vested at September 30, 2022		1,991,029		$	5.02		6.4	$	479
Exercisable at September 30, 2022		2,898,534		$	4.98		6.9	$	479

Summary of weighted-average assumptions to determine the fair value of the employee stock option

The weighted-average assumptions used in the Black-Scholes option pricing model to determine the fair value of the employee stock option grants were as follows:

	Three Months Ended September 30,						Nine Months Ended September 30,
	2022			2021			2022			2021
Risk-free interest rate		3.1	%		1.0	%		2.5	%		0.7	%
Expected volatility		93.6	%		90.7	%		87.2	%		72.9	%
Expected term (in years)		6.0			6.1			5.9			5.9
Expected dividend yield		—	%		—	%		—	%		—	%

Summary of PSU activity

Performance-Based Restricted Stock Units (PSUs)

The following table summarizes PSU activity as of September 30, 2022:

	Number of PSUs			Weighted-Average Grant Date Fair Value
Unvested at December 31, 2021		299,500		$	6.32
Granted		40,000			4.43
Cancelled		(30,000	)		6.69
Unvested at September 30, 2022		309,500		$	6.04

Summary of Non-cash stock-based compensation expense recorded

The following table summarizes stock-based compensation expense, including expense associated with award modifications for unvested options, reflected in the unaudited consolidated statements of operations and comprehensive loss (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2022		2021		2022		2021
Research and development	$	411	$	1,001	$	1,184	$	2,093
General and administrative		579		144		1,919		377
Total	$	990	$	1,145	$	3,103	$	2,470