Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2023

Stockholders' Equity Note [Abstract]

Shares of Common Stock Reserved for Future Issuance

Common stock reserved for future issuance are as follows in common equivalent shares:

	December 31,		December 31,
	2023		2022
Conversion of preferred stock		292,799		292,799
Common stock warrants		109,309		109,309
Stock options issued and outstanding for all plans		9,349,791		7,268,291
RSUs outstanding		246,853		483,282
Authorized for future option grants		723,977		1,114,248
Common stock authorized for the ESPP		658,955		449,671
Total		11,381,684		9,717,600

Summary of Shared Based Compensation Cost Included in Consolidated Statement of Operations

The share-based compensation recorded in the accompanying consolidated statements of operations for the years ended December 31, 2023 and 2022 is presented below (in thousands):

	Year Ended December 31,
	2023		2022
Research and development	$	2,574	$	2,782
General and administrative		5,075		10,766
Total	$	7,649	$	13,548

Summary of fair value of stock options is estimated using the Black-Scholes model

The fair value of stock options is estimated using the Black-Scholes model with the assumptions disclosed in the following table, excluding the former Chief Executive Officer option modifications:

	Year Ended December 31,
	2023	2022
Risk free interest rate	3.37% - 4.39%	1.82% - 3.97%
Expected option term	5.8 - 6.3 years	5.5 - 6.3 years
Expected volatility of common stock	86.9% - 92.1%	82.7% - 86.2%
Expected dividend yield	0.0%	0.0%

The fair value of the former Chief Executive Officer option modifications in 2022 was estimated using the Black-Scholes model with the assumptions disclosed in the following table:

Risk free interest rate	3.63% - 3.82%
Expected option term	3.6 - 6 years
Expected volatility of common stock	85.2% - 91.4%
Expected dividend yield	0.0%

Summary of Stock Option Activity for Company's Stock Option Plans

A summary of the stock option activity under the plans during the period ended December 31, 2023 is presented below (in thousands except for per share and weighted average term):

	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value
Outstanding at December 31, 2022		7,201		$	5.57		8.8	$	208
Granted		3,176		$	1.55
Exercised		(17	)	$	0.90			$	18
Cancelled		(1,010	)	$	4.32
Outstanding at December 31, 2023		9,350		$	4.35		8.3	$	1
Vested and exercisable at December 31, 2023		4,348		$	5.32		7.7	$	—
Outstanding and expected to vest as of December 31, 2023		9,350		$	4.35		8.3	$	1

Summary of Restricted Stock Units Activity

A summary of the restricted stock unit activity under the plans during the period ended December 31, 2023 is presented below (in thousands except for per share and weighted average term):

	RSUs			Weighted Average Grant Date Fair Value per Share		Weighted Average Remaining Contractual Term (Years)
Outstanding at December 31, 2022		483		$	3.83		1.3
Granted		—			—
Vested		(185	)	$	4.06
Cancelled		(51	)	$	8.16
Outstanding at December 31, 2023		247		$	3.58		0.8