Stock-Based Compensation

2015

Equity Plan

The

2015

Equity Plan provides for increases to the number of shares reserved for issuance thereunder each

January 1

equal to

4.0%

of the total shares of the Company's common stock outstanding as of the immediately preceding

December 31,

unless a lesser amount is stipulated by the Compensation Committee of the Company's board of directors. Accordingly,

2,560,618

shares were added to the reserve as of

January 1, 2021,

which shares

may

be issued in connection with the grant of stock-based awards, including stock options, restricted stock, restricted stock units, stock appreciation rights and other types of awards as deemed appropriate, in each case, in accordance with the terms of the

2015

Equity Plan. As of

December

31,

2020,

there were

shares of common stock available for future issuance under the

2015

Equity Plan. Further, the Company granted options to purchase

270,000

shares of common stock to employees during the year ended

December

31,

2020

that were granted outside of the

2015

Equity Plan as an inducement material to the employee's acceptance of employment with the Company in accordance with Nasdaq Listing Rule

5635

(c)(

). Generally, the options have a

ten

(

) year contractual term and vest in equal monthly installments over

three

(

) years.

The Company recorded stock-based compensation expense in the following expense categories of its consolidated statements of operations for the periods indicated:

	Year ended December 31,
	2020		2019
Research and development	$	164,791	$	54,155
General and administrative		571,328		461,607
Total stock-based compensation expense	$	736,119	$	515,762

The following table summarizes the activity related to all stock option:

	Number of Options			Weighted average exercise price per share		Weighted average remaining contractual life (in years)		Aggregate Intrinsic Value
Balance at January 1, 2019		203,736		$	88.14
Granted		117,270			2.62
Forfeited		(11,583	)		83.81
Expired		(147	)		276.00
Balance at December 31, 2019		309,276		$	55.78		6.98		—
Granted		1,931,100			0.68
Expired		(172	)		142.50
Outstanding at December 31, 2020		2,240,204		$	8.28		8.90	$	289,067
Exercisable at December 31, 2020		1,129,733		$	15.64		8.28	$	219,010
Vested and expected to vest at December 31, 2020		2,240,204		$	8.28		8.90	$	289,067

The weighted average grant date fair value of stock option awards granted was

$0.64

and

$2.16

during the years ended

December

31,

2020

and

2019,

respectively. The total fair value of options vested during the years ended

December

31,

2020

and

2019

were

$0.7

million and

$0.6

million, respectively.

options were exercised during any of the periods presented. At

December

31,

2020,

there was

$0.8

million of unrecognized compensation cost related to unvested options that will be recognized as expense over a weighted-average period of

2.2

years.

The grant date fair value of employee stock options is determined using the Black-Scholes Model. The following assumptions were used during the years ended

December

31,

2020

and

2019:

	2020			2019
Expected term (in years)	5.31	—	10.00	5.25	—	5.77
Risk-free interest rate	0.4%	—	1.7%	1.9%	—	2.5%
Expected volatility	113.4%	—	124.8%	112.4%	—	114.4%
Dividend yield	—	—	—	—	—	—

Restricted Stock Unit Awards

During the year ended

December

31,

2020,

the Company granted

153,000

restricted stock units to members of the board of directors of the Company. The weighted average grant date fair value of the restricted stock units granted during the year ended

December

31,

2020

was

$0.65.

The shares begin to vest

months after the grant date. The Company recognized approximately

$18,000

in expense related to these units during the year ended

December

31,

2020.

December

31,

2020,

there was approximately

$82,000

of unrecognized compensation cost that will be recognized over a weighted average period of

2.4

years.