Stock-based Compensation

3 Months Ended

Mar. 31, 2024

Stock-Based Compensation

Stock-Based Compensation

8. Stock-based compensation

Stock-based compensation expense was included in general and administrative and research and development as follows (in thousands):

	Three Months Ended March 31,
	2024		2023
General and administrative	$	71	$	(85)
Research and development		33		11
Total stock-based compensation	$	104	$	(74)

For stock options and RSUs granted under the 2019 Equity Incentive Plan, the 2021 Inducement Plan and the 2022 Equity Incentive Plan (the “2022 Plan”), as of March 31, 2024, unrecognized stock-based compensation cost totaled $786 thousand. The unrecognized stock-based expense is expected to be recognized over a weighted average period of 1.3 years.

Stock-based award plans

As of March 31, 2024, there were (i) 2,569 outstanding stock options under the 2019 Plan, and (ii) 3,125 outstanding stock options and 194,954 outstanding RSUs under the 2022 Plan. As of March 31, 2024, we had an aggregate of 416,227 shares available for future issuance, of which 4,166 shares were available under the 2021 Inducement Plan and 412,061 shares were available under the 2022 Plan.

Stock options

The following table summarizes the status of our outstanding and exercisable options and related transactions for the period presented (in thousands, except share and per share amounts):

	Outstanding						Exercisable
	Shares of			Weighted			Shares of			Weighted
	Common	Weighted		Average			Common	Weighted		Average
	Stock	Average		Remaining	Aggregate		Stock	Average		Remaining	Aggregate
	Issuable	Exercise		Contractual	Intrinsic		Issuable	Exercise		Contractual	Intrinsic
	for Options	Price		Term (years)	Value		for Options	Price		Term (years)	Value
As of January 1, 2024	4,700	$	398.30	8.6	$	—	4,577	$	391.04	8.6	$	—
Granted	—		—	—		—
Forfeited/Cancelled	—		—	—		—
As of March 31, 2024	4,700	$	398.30	8.3	$	—	4,607	$	392.96	8.3	$	—

The weighted average fair value per share of stock options granted for three months ended March 31, 2023 was $3.63. We estimated the grant date fair value of stock options granted to employees, consultants, and directors using the Black-Scholes option pricing model. We do not have history to support a calculation of volatility and expected term; as such, we have used a weighted-average volatility considering the volatilities of several guideline companies. In identifying similar entities, we considered characteristics such as industry, length of trading history, and stage of life cycle. The assumed dividend yield was based on our expectation of not paying dividends in the foreseeable future. The average expected life of the stock options was determined based on the mid-point between the vesting date and the end of the contractual term, known as the “simplified method,” or the contractual term in cases where the “simplified method” was precluded. The risk-free interest rate is determined by reference to implied yields available from U.S. Treasury securities with a remaining term equal to the expected life assumed at the date of grant.

The assumptions used in the Black-Scholes option-pricing model are as follows:

	Three Months Ended
	March 31, 2023
Expected stock price volatility	82.9	%
Expected life of stock options (years)	5.0
Expected dividend yield	—	%
Risk free interest rate	3.54	%

Restricted Stock Units

The following table summarizes the status of our RSUs and related transactions for the period presented (in thousands, except share and per share amounts):

	Outstanding					Vested
	Shares of	Average				Shares of	Average
	Common Stock	Grant Date		Aggregate		Common Stock	Grant Date		Aggregate
	Issuable	Fair Value		Intrinsic		Issuable	Fair Value		Intrinsic
	for RSUs	Price		Value		for RSUs	Price		Value
As of January 1, 2024	141,361	$	4.55	$	523	5,468	$	4.02	$	20
Granted	53,593		6.24
Vested						—		—
Released	—		—			—		—		—
Forfeited/Cancelled	—		—
As of March 31, 2024	194,954	$	5.02	$	797	5,468	$	4.02	$	22

We estimated the grant date fair value of restricted stock units granted to employees, consultants, and directors based on the closing sales price of our common stock as reported on Nasdaq on the date of grant.