Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2024

Share-Based Payment Arrangement [Abstract]

Summary of common stock reserved for future issuance

As of June 30, 2024, the Company had reserved shares of its common stock for future issuance as follows:

	Shares Reserved
Common stock options outstanding		4,671,290
Unvested restricted stock units		311,500
Available for future grants under the 2021 Equity Incentive Plan		4,423,667
Available for future grants under the 2021 Employee Stock Purchase Plan		780,098
Total shares of common stock reserved		10,186,555

Summary of the Company's stock option activity

A summary of the Company’s stock option activity and related information for the six months ended June 30, 2024 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, 2023		5,301,254		$	4.76		6.9	$	—
Forfeited/Expired		(629,964	)	$	4.90
Outstanding at June 30, 2024		4,671,290		$	4.74		6.9	$	—
Vested at June 30, 2024		3,348,616		$	5.04		6.5	$	—
Exercisable at June 30, 2024		3,516,983		$	5.03		6.5	$	—

Summary of RSU activities

RSUs consist of time-based units (TSUs), performance-based units (PSUs) and market-based units (MSUs). The following table summarizes RSU activities during the six months ended June 30, 2024:

	Number of RSUs			Weighted-Average Grant Date Fair Value
Unvested at December 31, 2023		326,500		$	5.90
Cancelled		(15,000	)	$	6.98
Unvested at June 30, 2024		311,500		$	5.85

Summary of Non-cash stock-based compensation expense recorded

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

	Three Months Ended June 30,				Six Months Ended June 30,
	2024		2023		2024		2023
Research and development	$	244	$	494	$	497	$	967
General and administrative		745		713		1,570		1,397
Total	$	989	$	1,207	$	2,067	$	2,364