Stock-based Compensation

3 Months Ended

Mar. 31, 2023

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

9. Stock-Based Compensation

Summary of Stock Option Activity

Transactions related to stock options awarded to employees and directors during the three months ended March 31, 2023 were as follows:


	Shares			Weighted average exercise price		Weighted average remaining contractual life (years)		Aggregate intrinsic value
Options outstanding at December 31, 2022		249,403		$	105.87		8.12	$	3
Granted		195,895			4.27
Forfeited		(15,638	)		22.41
Options outstanding at March 31, 2023		429,660		$	62.59		6.77	$	10
Options exercisable at March 31, 2023		109,601		$	171.38		7.26	$	10

The aggregate intrinsic value represents the total intrinsic value (the difference between the fair value of the common stock as of March 31, 2023 and the exercise price, multiplied by the number of in-the-money options) that would have been received by the option holders had all option holders exercised their options on March 31, 2023. This amount is impacted by changes in the fair value of the common stock.

Stock-Based Compensation

Stock-based compensation relates to non-employee directors and non-employees, time-based stock options and restricted stock units granted. Total stock-based compensation expense related to all of the Company’s stock-based awards was recognized as follows (in thousands):


	Three Months Ended March 31,
	2023		2022
Research and development	$	288	$	360
General and administrative		309		562
Total stock-based compensation expense	$	597	$	922