Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2023

Retirement Benefits [Abstract]

Summary of Stock Option Activity

A summary of stock option activity for the six months ended June 30, 2023, is presented below (in thousands, except per share and contractual life data).

	Number of Shares			Weighted Average Exercise Price Per Share		Weighted Average Remaining Contractual Life (in Years)
Options outstanding as of December 31, 2022		5,272		$	3.07		7.15
Granted		1,122		$	1.25
Exercised		(101	)	$	0.44
Forfeited or expired		(154	)	$	2.78
Options outstanding, vested and expected to vest as of June 30, 2023		6,139		$	2.79		7.03
Options exercisable as of June 30, 2023		3,941		$	3.29		5.94

Summary of Restricted Stock Unit

The following table summarizes restricted stock unit (“RSU”) activity for the six months ended June 30, 2023 (in thousands, except per share data):

	Number of Shares		Weighted Average Grant Date Fair Value Per Share
Outstanding as of December 31, 2022		—	$	—
Awarded		403		0.93
Vested and released		—		—
Forfeited/canceled		—		—
Outstanding as of June 30, 2023		403	$	0.93

Stock-based Compensation Expense

Stock-based compensation expense recognized for stock-based awards in the condensed consolidated statements of operations for the three and six months ended June 30, 2023, and 2022 was as follows (in thousands):

	Three Months Ended June 30,				Six Months Ended June 30,
	2023		2022		2023		2022
Research and development	$	284	$	324	$	532	$	514
General and administrative		240		70		361		220
Total	$	524	$	394	$	893	$	734