Stock-Based Compensation

12 Months Ended

Dec. 31, 2022

Share-Based Payment Arrangement [Abstract]

Note 9. Stock-Based Compensation

Stock Option Plans

The Company has three stock compensation plans, the 2020 Stock Incentive Plan (the “2020 Plan”), the 2014 Stock Incentive Plan (the “2014 Plan”) and the 2007 Stock Incentive Plan (the “2007 Plan”). The 2020 Plan permits the Company to make grants of incentive stock options, non-statutory stock options, restricted stock, restricted stock units, stock appreciation rights and other stock-based awards to the Company’s employees, officers, directors, consultants and advisors; however, incentive stock options may only be granted to the Company’s employees. The number of shares initially reserved for issuance under the 2020 Plan was 4,860,000 shares of common stock and may be increased by the number of shares under the 2014 Plan that expire, terminate or are otherwise surrendered, cancelled, forfeited or repurchased by the Company. Options remain outstanding under the 2007, 2014 and the 2020 Plan. As of December 31, 2022, there were 1,151 and 72,519 options outstanding under the 2007 Plan and 2014 Plan, respectively. Options granted under the 2007, 2014 and 2020 Plans generally expire ten years from the date of grant. The Company intends for the 2020 Plan to be its primary stock compensation plan in the future. As of December 31, 2022, there were 1,733,392 options outstanding and 3,126,608 shares available to issue under the 2020 Plan.

The 2014 Plan was closed to new grants following the approval of the 2020 Plan, and therefore, there were no shares reserved for issuance under the 2007 and 2014 Plan as of December 31, 2022.

The following table summarizes all option activity under the 2007 Plan, 2014 Plan, 2020 Plan and inducement grants:


	Shares Issuable Under Options			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
						(In years)
Outstanding as of January 1, 2021		3,621,479		$	10.63		8.9	$	—
Granted		702,836			10.69		—		—
Options Assumed		(174	)		4.73		—		—
Forfeited / Canceled		(110,164	)		19.50		—		—
Outstanding as of December 31, 2021		4,213,977		$	10.33		8.4	$	—
Granted		1,267,700			3.81		—		—
Forfeited / Canceled		(263,644	)		12.12		—		—
Outstanding as of December 31, 2022		5,218,033		$	8.69		8.1	$	—
Options vested and expected to vest as of December 31, 2022		5,218,033		$	8.69		8.1	$	—
Options exercisable as of December 31, 2022		3,076,338		$	8.72		7.0	$	—

As of December 31, 2022, the range of exercise prices was between $2.45 and $2,147 for options outstanding.

Intrinsic value is calculated as the difference between the exercise price of the underlying options and the fair value of the common stock for the options that had exercise prices that were lower than the fair value per share of the common stock on the date of exercise. There was no aggregate intrinsic value of options exercised during the year ended December 31, 2022.

The following table presents the assumptions used in the Black-Scholes option pricing model to determine the fair value of stock options granted in the periods presented, as follows:


	Year Ended December 31,
	2022	2021
Expected stock price volatility	81% - 84%	105% - 110%
Risk-free interest rate	1.8% - 4.2%	1%
Expected life of option (in years)	6.25 - 6.50	6.25 - 6.75
Estimated dividend yield	0%	0%

Restricted Stock Units

The following table shows the RSU activity, as follows:


	Shares Issuable Under RSUs			Weighted Average Exercise Price		Aggregate Intrinsic Value

Outstanding as of January 1, 2021		—		$	—	$	—
Granted		20,000			5.07		—
RSUs Vested		—			—		—
Forfeited / Canceled		—			—		—
Outstanding as of December 31, 2021		20,000		$	5.07	$	—
Granted		15,000			2.47		—
RSUs Vested		(20,000	)		5.07		—
Forfeited / Canceled		—			—		—
Outstanding as of December 31, 2022		15,000		$	2.47	$	—
RSUs vested and expected to vest as of December 31, 2022		15,000		$	2.47	$	—
RSUs exercisable as of December 31, 2022		—		$	—	$	—

Stock-based Compensation Expense

Total compensation expense related to all of the Company’s stock-based awards for the years ended December 31, 2022 and 2021 was comprised of the following (in thousands):


	Year Ended December 31,
	2022		2021
Stock-based compensation classified as:
Research and development expense	$	3,230	$	3,166
General and administrative expense		4,923		4,738
Total stock-based compensation expense	$	8,153	$	7,904

As of December 31, 2022, total unrecognized stock-based compensation expense related to non-vested equity awards was $10.5 million, which is expected to be recognized over an estimated weighted-average period of 2.5 years.