Equity Incentive Plans (Tables)

6 Months Ended

Jun. 30, 2022

Equity Incentive Plans

Assumptions used in the black-Scholes model

The assumptions used in the Black-Scholes model are presented below:

	Six months ended
	June 30, 2022	June 30, 2021
Risk-free interest rate	2.65% - 3.52%	0.90% - 1.29%
Expected volatility	84.81% - 85.67%	93.37%
Expected term (in years)	5.50 - 7.00	5.50 - 7.00
Expected dividend yield	0%	0%

Allocation of Stock-Based Compensation Expenses

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

	Three Months Ended June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
Research and development	$	489,000	$	399,000	$	679,000	$	752,000
General and administrative		460,000		508,000		763,000		997,000
Total stock-based compensation	$	949,000	$	907,000	$	1,442,000	$	1,749,000

Summary of Stock Option Activity

Stock option transactions during the six months ended June 30, 2022 are presented below:

	Options Outstanding
				Weighted
				Average
		Weighted		Remaining
		Average		Contractual	Aggregate
		Exercise		Term	Intrinsic
	Shares	Price		(Years)	Value
Outstanding at December 31, 2021	2,409,682	$	5.64	8.00		—
Granted	1,173,000		5.08			—
Exercised	(21,775)		3.29		$	27,000
Forfeited/Cancelled	(180,229)		7.34			—
Outstanding at June 30, 2022	3,380,678	$	5.37	8.30	$	926,000
Vested and expected to vest at June 30, 2022	3,380,678	$	5.37	8.30	$	926,000
Exercisable at June 30, 2022	1,266,771	$	6.63	4.79	$	639,000

Schedule of restricted stock awards

Restricted stock awards and restricted stock units during the six months ended June 30, 2022 are presented below:

		Weighted Avg
		Grant Date
	Shares	Fair Value
Outstanding at December 31, 2021	154,018	$	27.49
Granted	—		—
Forfeited/Cancelled	(369)		31.85
Vested and Issued as Common Stock	(23,983)		4.10
Outstanding at June 30, 2022	129,666	$	27.48

Shares Reserved for Future Issuance

As of June 30, 2022, the Company had reserved shares of its common stock for future issuance as follows:

	Shares Reserved
Stock options outstanding	3,380,678
Unvested restricted stock units	30,000
Employee stock purchase plan	9,748
Available for future grants under the 2016 Plan	569,937
Warrants outstanding	20,549,338
Total shares reserved	24,539,701