On August 5, 2014, the Company approved a stock option grant plan (the “2014 Equity Incentive Plan”) for employees, directors, and non-employee consultants, which provides for the issuance of options to purchase common stock. The total shares authorized under the plan was originally 8,000,000; however, during 2019, the Plan was amended to increase the total shares authorized under the plan to 16,000,000. As a result of the Business Combination, the 2014 Equity Incentive Plan was amended to reduce the shares authorized to 7,444,800 based upon the impact of the Exchange Ratio.

As a result of the Business Combination, the Company adopted the 2021 Omnibus Equity Incentive Plan (hereinafter collectively with the 2014 Equity Incentive Plan referred to as the "Equity Compensation Plans"), representing 11,000,000 shares of common stock reserved for issuance under the 2021 Omnibus Equity Incentive Plan. As of the beginning of the 2022 calendar year, the shares reserved for future issuance increased by, 869,746, or two percent (2%) of the total number of shares of Common Stock issued and outstanding, to a total of 11,869,746 shares of common stock reserved for issuance under the 2021 Omnibus Equity Incentive Plan.

The expected term of the stock options was estimated using the “simplified” method, as defined by the SEC’s Staff Accounting Bulletin No. 107, Share-Based Payment. The volatility assumption was determined by examining the historical volatilities for industry peer companies, as the Company does not have sufficient trading history for its common stock. The risk-free interest rate assumption is based on the U.S. Treasury instruments whose term was consistent with the expected term of the options. The dividend assumption is based on the Company’s history and expectation of dividend payouts. The Company has never paid dividends on its common stock and does not anticipate paying dividends on its common stock in the foreseeable future. Therefore, the Company has assumed no dividend yield for purposes of estimating the fair value of the options.

Stock option activity for employees and non-employees under the Equity Compensation Plans for the six months ended June 30, 2022 was as follows:


	Options			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (years)		Aggregate Intrinsic Value
Outstanding options, December 31, 2021		5,107,672		$	2.44		5.78	$	28,948,535
Granted		528,711		$	2.84
Forfeited		(256,475	)	$	4.81
Exercised		(90,264	)	$	0.85
Outstanding options, June 30, 2022		5,289,644		$	2.64		4.88	$	2,146,863
Options vested and exercisable, June 30, 2022		3,950,063		$	1.34		3.69	$	2,146,863

Total unrecognized compensation cost related to non-vested stock options as of June 30, 2022 was approximately $5.2 million and is expected to be recognized within future operating results over a weighted-average period of 2.13 years.

The weighted average grant date fair value of options granted during the three months ended June 30, 2022 and 2021, was $1.79 per share and $5.40 per share, respectively. During the three months ended June 30, 2022 and 2021, 134,986 shares with a fair value totaling $595 thousand, and 151,577 shares with a fair value totaling $668 thousand, respectively, vested.

The weighted average grant date fair value of options granted during the six months ended June 30, 2022 and 2021, was $1.76 per share and $5.21 per share, respectively. During the six months ended June 30, 2022 and 2021, 315,370 shares with a fair value totaling $1.3 million, and 231,348 shares with a fair value totaling $0.9 million, respectively, vested.

The estimated fair value of stock options granted to employees and consultants during the three and six months ended June 30, 2022 and 2021, were calculated using the Black-Scholes option-pricing model using the following assumptions:


	Three Months Ended June 30,						Six Months Ended June 30,
	2022			2021			2022			2021
Expected volatility	85.4		%	75.9 - 104.3		%	78.0 - 85.4		%	75.9 - 104.3		%
Weighted-average volatility		85.4	%		96.7	%		79.0	%		98.1	%
Expected dividends	—		%	—		%	—		%	—		%
Expected term (in years)	5.89			6.25			5.50 - 6.08			6.25
Risk-free rate	3.03		%	0.14 - 0.59		%	1.38 - 3.03		%	0.14 - 0.59		%

Stock award activity for employees and non-employees under the Equity Compensation Plans for the six months ended June 30, 2022 was as follows:


	Number of shares		Weighted Average Grant Date Fair Value
Unvested as of December 31, 2021		—	$	—
Granted		300,000	$	1.89
Vested		—	$	—
Forfeited		—	$	—
Unvested as of June 30, 2022		300,000	$	1.89

Total unrecognized compensation cost related to non-vested stock awards as of June 30, 2022 was approximately $0.6 million and is expected to be recognized within future operating results over a weighted-average period of 3.93 years.

Stock-based compensation expense for the three and six months ended June 30, 2022 and 2021 was as follows:


	Three Months Ended June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
Research and development	$	149,814	$	303,461	$	518,039	$	514,404
General and administrative		420,047		129,970		949,422		268,142
Total	$	569,861	$	433,431	$	1,467,461	$	782,546