Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2013

Stock-Based Compensation [Abstract]

Stock-Based Compensation Expense

The Company recorded stock-based compensation expense in the statements of operations as follows (in thousands):

	Three Months Ended March 31,
	2013		2012
Research and development	$	217	$	183
General and administrative		266		404
Total stock-based compensation expense	$	483	$	587

Summary of Option Activity

The following is a summary of option activity under the 2005 Plan and the 1995 Plan for the three months ended March 31, 2013:

	2005 Stock Incentive Plan					1995 Stock Option Plan
	Stock Options			Weighted- Average Exercise Price		Stock Options		Weighted- Average Exercise Price
Outstanding at January 1, 2013		9,143,825		$	1.87		211,900	$	4.94
Granted		3,347,500		$	1.83		-	$	-
Exercised		(1,500	)	$	0.56		-	$	-
Canceled		(355,458	)	$	1.62		-	$	-
Outstanding at March 31, 2013		12,134,367		$	1.87		211,900	$	4.94
Shares exercisable at March 31, 2013		4,442,548		$	2.18		211,900	$	4.94
Shares available for grant at March 31, 2013		2,760,319

Assumptions used to Estimate Grant Date Fair Value of Stock Options granted using Black-Scholes Option-Pricing Model

The fair value of stock options granted was estimated at the date of grant using the Black-Scholes option-pricing model with the following assumptions:

	Three Months Ended March 31,
	2013			2012
Weighted-average fair value of stock options granted	$	1.00		$	0.71
Risk-free interest rate		0.62%-1.34	%		0.82%-1.54	%
Dividend yield		0	%		0	%
Volatility		69.23%-73.72	%		75.52%-80.48	%
Expected term (in years)		4.06-7.05			3.34-7.09
Expected forfeiture rate		0%-23.15	%		0%-23.15	%

Summary of Restricted Stock Awards Activity

The following is a summary of restricted stock awards activity for the three months ended March 31, 2013:

	Number of Shares		Per Share Weighted- Average Grant-Date Fair Value
Outstanding at January 1, 2013		33,334	$	1.39
Restricted stock granted		-	$	-
Restricted stock vested		-	$	-
Restricted stock forfeited		-	$	-
Outstanding at March 31, 2013		33,334	$	1.39