Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2016

Share-Based Payment Arrangements [Abstract]

Summary of option activity under the Plans

Stock Options

The following table summarizes stock options activity for the three months ended March 31, 2016 (in thousands, except per share data):

	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life
Outstanding at January 1, 2016		5,134		$	9.05		5.69
Granted		927		$	4.52
Exercised		-		$	-
Cancelled		(126	)	$	6.11
Expired		(62	)	$	27.66
Outstanding at March 31, 2016		5,873		$	8.20		6.26
Exercisable at March 31, 2016		4,051		$	9.46		4.91
Vested and expected to vest at March 31, 2016		5,492		$	8.39		6.03

Assumptions used in computing the fair value of option grants

	Three Months Ended March 31,
	2016		2015
Risk-free interest rate		1.55%		1.91%
Expected life (in years)		6.71		6.71
Expected volatility		75%		81%
Expected dividend yield		-		-

Compensation expense of shares, granted to both employees and non-employees

Stock-based compensation expense for the three months ended March 31, 2016 and 2015 was recorded in our condensed consolidated statement of operations as follows (in thousands):

	Three Months Ended March 31,
	2016		2015
Research and development expenses	$	275	$	390
General and administrative expenses		301		367
Total stock-based compensation expense	$	576	$	757