Equity Incentive Plans (Tables)

3 Months Ended

Mar. 31, 2023

Equity Incentive Plans

Assumptions used in the black-Scholes model

The assumptions used in the Black-Scholes model during the three months ended March 31, 2023 are presented below. There were no stock options granted during the three months ended March 31, 2022.

	Three months ended
	March 31, 2023
Risk-free interest rate	3.54% - 4.20%
Expected volatility	90.99% - 91.58%
Expected term (in years)	5.5 - 7.0
Expected dividend yield	0%

Allocation of Stock-Based Compensation Expenses

The tables below summarize the total share-based compensation expense included in the Company’s consolidated statements of operations for the periods presented:

	Three Months Ended March 31,
	2023		2022
Research and development	$	545,000	$	303,000
General and administrative		312,000		190,000
Total share-based compensation	$	857,000	$	493,000

Summary of Stock Option Activity

Stock option transactions during the three months ended March 31, 2023 are presented below:

	Options Outstanding
				Weighted
				Average
		Weighted		Remaining
		Average		Contractual	Aggregate
		Exercise		Term	Intrinsic
	Shares	Price		(Years)	Value
Outstanding at December 31, 2022	3,352,803	$	5.32	7.8
Granted	17,500		2.36
Exercised	—		—		$	—
Forfeited/Cancelled	(4,874)		25.99
Outstanding at March 31, 2023	3,365,429	$	5.27	7.6	$	1,375
Vested and expected to vest at March 31, 2023	3,365,429	$	5.27	7.6	$	1,375
Exercisable at March 31, 2023	1,530,910	$	6.04	6.5	$	—

Shares Reserved for Future Issuance

As of March 31, 2023, the Company had reserved shares of its Common Stock for future issuance as follows:

	Shares Reserved
Stock options outstanding	3,365,429
Unvested restricted stock units	129,666
Employee stock purchase plan	9,748
Available for future grants under the 2016 Plan	563,445
Warrants outstanding	20,549,338
Total shares reserved	24,617,626