The Company has granted options to employees, directors, and consultants under the 2015 Equity Incentive Plan (the "2015 Plan"). The 2015 Plan provides for the grant of incentive stock options ("ISOs"), nonstatutory stock options, restricted stock awards, restricted stock units, stock appreciation rights, performance-based stock awards and other stock-based awards. Additionally, the 2015 Plan provides for the grant of performance-based cash awards. ISOs may be granted only to the Company's employees. All other awards may be granted to the Company's employees, including officers, and to non-employee directors and consultants. As of December 31, 2022 and 2021, there were 47,228 and 41,068 shares, respectively, remaining available for the grant of stock option under the 2015 Plan.

During the twelve months ended December 31, 2022 and 2021, the Company awarded 51,360 and 3,160, respectively, stock options to its employees and directors, pursuant to the plan described above. Stock options generally vest over one to four years and have a contractual term of ten years. Stock options are valued using the Black-Scholes option pricing model and compensation cost is recognized based on the resulting value over the service period. Expected volatilities utilized in the model are based on implied volatilities from traded stocks of peer companies. Similarly, the dividend yield is based on historical experience and the estimate of future dividend yields. The risk-free interest rate is derived from the U.S. Treasury yield curve in effect at the time of grant. The expected term of the options is based on the average period the stock options are expected to remain outstanding. The fair value of the option grants of $0.5 million and $0.1 million respectively, has been estimated with the following assumptions for the year ended December 31, 2022 and 2021:

The following table summarizes stock option activity for employees and non-employees for the twelve months ended December 31, 2022 and 2021:


	Shares	Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value
Outstanding at December 31, 2020	62,559	$	69.50	4.87	$	175,770
Granted	3,160	32.50
Exercised	—	—
Forfeited	(1,800)	—
Expired	—	—
Outstanding at December 31, 2021	63,919	$	68.75	8.50	$	—
Exercisable at December 31, 2021	27,334	$	121.25	8.21	$	—

Granted	51,360	$	10.95
Exercised	—
Forfeited	(6,776)
Expired	(1,375)
Outstanding at December 31, 2022	107,128	$	23.67	8.29	$	—
Exercisable at December 31, 2022	38,100	$	35.85	7.63	$	—

As of December 31, 2022 and 2021, there was approximately $0.8 million and $0.9 million of total unrecognized compensation cost, respectively, related to unvested stock options. Total unrecognized compensation cost will be adjusted for future changes in employee and non-employee forfeitures, if any. The Company expects to recognize that cost over a remaining weighted-average period of 2.13 years.

During the year ended December 31, 2021, the Company granted 3,160 stock options, in the aggregate, to certain employees. These awards vest monthly over 4 years as continuous services are provided, and expense is being recognized over this period. Total compensation cost related to stock options was $0.5 million for the year ended December 31, 2021.

During the year ended December 31, 2022, the Company granted 51,360 stock options, in the aggregate, to certain employees and directors. These awards vest over 1 year to 4 years as continuous services are provided, and expense is being recognized over this period. Total compensation cost related to stock options was $0.5 million for the year ended December 31, 2022

During the year ended December 31, 2022 and 2021, the Company granted 9,712 and 2,958 shares of common stock to its Employee Stock Purchase Plan ("ESPP") participants. Fair value of the grants are valued using the Black-Scholes option pricing model and compensation cost is recognized based on the resulting value over the derived service period.