Stock-Based Compensation

3 Months Ended

Mar. 31, 2019

9. Stock-Based Compensation

The Company recognized stock-based compensation expense on all employee and non-employee awards as follows:

	For the three months ended March 31,
(in thousands)	2019		2018
Research and development	$	433	$	603
General and administrative		1,023		3,056
Stock-based compensation expense	$	1,456	$	3,659

The Company granted an aggregate of 1,496,333 stock options during the three months ended March 31, 2019 with a weighted-average grant date fair value of $1.62 per share. The Company granted an aggregate of 7,500 stock options during the three months ended March 31, 2018 with a weighted-average grant date fair value of $3.00 per share.

The Company recognizes

forfeitures

as they occur.

For the three months ended March 31, 2019 and 2018, the fair value of stock options was estimated on the date of grant using a Black-Scholes option valuation model with the following assumptions:

	For the three months ended March 31,
	2019	2018
Risk-free interest rate	2.28 - 2.53%	2.56 - 2.74%
Expected life in years	6 - 6.25	6
Expected volatility	78.87 - 85.00%	80.75 - 81.10%
Expected dividend yield	0	0

Stock option activity under the Company’s stock option plan for the three months ended March 31, 2019 is as follows:

(in thousands, except share and per share data)	Number of Shares			Weighted- Average Exercise Price		Weighted- Average Contractual Term (Years)		Aggregate Intrinsic Value
Outstanding, December 31, 2018		5,277,085		$	4.24
Granted		1,496,333			2.24
Exercised		—			—
Cancelled		(1,357,333	)		4.33
Outstanding, March 31, 2019		5,416,085		$	3.66		7.82	$	5,494
Options exercisable, March 31, 2019		2,213,008		$	5.14		5.33	$	1,025
Options exercisable, December 31, 2018		3,099,935		$	5.15		4.93	$	88
Options available for future grant		3,996,638

At March 31, 2019, total unrecognized compensation costs related to unvested stock options outstanding amounted to $6.2 million. The cost is expected to be recognized over a weighted-average period of 1.61 years.

A summary of the status of unvested restricted stock for the three months ended March 31, 2019 is as follows:

	Number of Shares			Weighted-Average Grant Date Fair Value
Non-vested, December 31, 2018		682,070		$	3.47
Granted		1,393,536			2.24
Vested		(446,428	)		2.24
Cancelled		(7,333	)		4.14
Non-vested, March 31, 2019		1,621,845		$	2.92

At March 31, 2019, total unrecognized compensation costs related to unvested restricted stock outstanding amounted to $4.1 million. The cost is expected to be recognized over a weighted-average period of 1.59 years.