Stock-Based Compensation

9 Months Ended

Sep. 30, 2018

Stock-Based Compensation

Stock-Based Compensation

(9)  Stock-Based Compensation

A summary of stock option activity for the nine months ended September 30, 2018 is as follows:

		Weighted		Weighted
		Average		Average
		Exercise		Remaining
		Price		Contractual
	Shares	Per Share		Term (In Years)
Options Outstanding at December 31, 2017	10,856,212	$	9.40	6.1
Granted	5,056,467		0.61
Exercised	(104,500)		2.80
Canceled	(2,568,090)		8.76
Options Outstanding at September 30, 2018	13,240,089		6.22	7.4
Options Vested and Expected to Vest at September 30, 2018	12,884,023		6.36	7.3
Options Exercisable at September 30, 2018	6,190,301		10.97	5.2
Shares Available for Grant Under the 2008 Plan	5,096,110

The weighted average grant-date fair value of stock options granted during the three and nine month periods ended September 30, 2018 was $0.30 and $0.44, respectively. Stock-based compensation expense for the three and nine month periods ended September 30, 2018 and 2017 was recorded as follows:

	Three months ended  September 30,				Nine months ended September 30,
	2018		2017		2018		2017
	(In thousands)				(In thousands)
Research and development	$	799	$	1,546	$	3,088	$	5,310
General and administrative		994		1,193		3,241		4,418
Total stock-based compensation expense	$	1,793	$	2,739	$	6,329	$	9,728

The fair values of employee and director stock options granted during the three and nine month periods ended September 30, 2018 and 2017 were valued using the Black-Scholes option pricing model with the following assumptions:

	Three months ended  September 30,				Nine months ended September 30,
	2018		2017		2018		2017
Expected stock price volatility	85	%	76	%	73-85	%	76-77	%
Expected option term	6.0	Years	6.0	Years	6.0	Years	6.0	Years
Risk-free interest rate	2.8	%	2.0	%	2.8-3.0	%	2.0-2.3	%
Expected dividend yield	None		None		None		None