Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2023

Stock-Based Compensation

Schedule of stock-based compensation expense

	Year Ended December 31,
	2023		2022
Research and development expense	$	2,189	$	2,427
General and administrative expense		5,193		5,997
Total stock-based compensation expense	$	7,382	$	8,424

Summary of stock option activity

				Weighted
				Average
				Remaining	Aggregate
		Weighted		Contractual	Intrinsic
	Number of	Average		Term	Value (1)
	Stock Options	Exercise Price		(In years)	(In thousands)
Outstanding as of December 31, 2022	4,960,553	$	8.04	8.6	$	89
Granted	3,738,555	$	2.75
Exercised	(2,757)	$	2.82
Cancelled/forfeited	(1,240,556)	$	7.26
Outstanding as of December 31, 2023	7,455,795	$	5.52	8.0	$	-
Exercisable as of December 31, 2023	3,103,732	$	7.04	6.6	$	-

(1) The aggregate intrinsic value of stock options is calculated as the difference between the exercise price of the stock options and the fair value of the Company’s common stock for those stock options that had exercise prices lower than the fair value of the Company’s common stock as of the end of the period.

Schedule of assumptions used in determining fair value of options granted

	Year Ended December 31,
	2023			2022
Risk-free interest rate		3.57 - 4.40	%		1.47 – 4.22	%
Expected dividend yield		0	%		0	%
Expected term (in years)		5.5 - 6.1			5.3 – 6.1
Expected volatility		81.7 - 87.3	%		80.8 – 87.6	%

Summary of restricted stock activity

	Number	Weighted
	of Shares	Average
	of Restricted	Grant Date
	Stock	Fair Value
Unvested as of December 31, 2022	46,160	$	5.51
Vested	(39,250)	$	5.51
Canceled/Forfeited	(1,293)	$	5.51
Unvested as of December 31, 2023	5,617	$	5.51