The Company has two stock compensation plans, the 2014 Stock Incentive Plan (the “2014 Plan”) and the 2007 Stock Incentive Plan (the “2007 Plan”). The 2014 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 2014 Plan was 1,700,000 shares of common stock and may be increased by the number of shares under the 2007 Plan that expire, terminate or are otherwise surrendered, cancelled, forfeited or repurchased by the Company. The number of shares of common stock that may be issued under the plan is also subject to an annual increase on the first day of each fiscal year equal to the lesser of (i) 1,800,000 shares of the Company’s common stock, (ii) 4% of the number of shares of the Company’s common stock outstanding on the first day of the applicable fiscal year or (iii) an amount determined by the Company’s board of directors. Options remain outstanding under both the 2007 and the 2014 Plan. The number of shares subject to and the exercise prices applicable to these outstanding options were adjusted in connection with the one for nine reverse stock-split. As of December 31, 2019, there were 84,612 options outstanding under the 2007 plan. Options granted under the 2007 and 2014 Plans generally expire ten years from the date of grant. The Company intends for the 2014 Plan to be its primary stock compensation plan in the future.

Effective as of August 1, 2018, the Board of Directors amended the Company’s 2014 Stock Incentive Plan (the “2014 Plan”) and the Company’s 2014 Employee Stock Purchase Plan (the “ESPP” and, together with the 2014 Plan, the “Plans”) to reduce the share reserves under the Plans. These reductions were made to equitably adjust the share reserves in accordance with the terms of the Plans. As a result of these equitable adjustments: (1) the number of shares of common stock authorized for issuance under the 2014 Plan (excluding shares underlying outstanding awards as of August 1, 2018) was reduced to 766,500 shares and the maximum number of shares that can be added to the 2014 Plan under evergreen provision set forth in Section 4(a)(1)(C) of the 2014 Plan was reduced to 550,000 shares annually; and (2) the number of shares of common stock authorized for future issuance under the ESPP was reduced to 209,500 shares (excluding shares previously issued under the ESPP prior to August 1, 2018) and the maximum number of shares that can be added to the ESPP under the evergreen provision set forth in the ESPP was reduced to 135,000 shares annually. The 2014 Plan and ESPP were amended and restated as of August 1, 2018 to reflect these equitable adjustments.

As of December 31, 2019, a total of 337,955 stock awards were available for grant under the 2014 Plan.

	Shares Issuable Under Options and PRSUs			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
						(In years)		(In thousands)
Outstanding as of January 1, 2018		782,340		$	14.28		8.8	$	8.5
Granted		267,950			5.02
Exercised		(15,120	)		4.74
Forfeited / Canceled		(60,353	)		7.31
Outstanding as of December 31, 2018		974,817			12.31		8.2		—
Granted		815,400			1.75
PRSUs vested		(78,450	)		4.83
Forfeited / Canceled		(11,500	)		4.41
Outstanding as of December 31, 2019		1,700,267		$	7.64		8.2	$	—
Stock awards vested and expected to vest as of December 31, 2019		1,645,267		$	7.64		8.2	$	—
Options exercisable as of December 31, 2019		882,576		$	12.49		7.3	$	—

As of December 31, 2019, the range of exercise prices was between $0.67 and $119.25 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 years ended December 31, 2019 and 2018.

As of December 31, 2019, total unrecognized stock-based compensation expense related to non-vested equity awards was $1.3 million, which is expected to be recognized over an estimated weighted-average period of 2.2 years.

Total compensation expense related to all of the Company’s stock-based awards for the years ended December 31, 2019 and 2018 was comprised of the following (in thousands):

	Year Ended December 31,
	2019		2018
Stock-based compensation classified as:
Research and development expense	$	343	$	249
General and administrative expense		965		1,294
Total stock-based compensation expense	$	1,308	$	1,543

Stock-based compensation expense for the year ended December 31, 2019 included no stock-based compensation expense related to a performance-based option granted during 2019.

During the year ended December 31, 2019, PRSUs awarded to employees totaling 78,450 shares vested and resulted in the recognition of $379,000 in stock-based compensation expense.

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: