STOCK-BASED COMPENSATION AND STOCK PLANS (Tables)

3 Months Ended

Mar. 31, 2017

Compensation and Retirement Disclosure [Abstract]

Schedule of stock-based compensation expense

	Three Months Ended March 31,
	2017		2016
Research and development	$	130	$	190
General and administrative		413		404
Total stock-based compensation expense	$	543	$	594

Schedule of activity of options under stock plans

Stock Options	Number of Shares			Weighted Average Exercise Price
Outstanding as of December 31, 2016		8,715,048		$	3.71
Granted		982,500			1.53
Exercised		—			—
Cancelled		(193,458	)		5.98
Outstanding as of March 31, 2017		9,504,090		$	3.44
Exercisable as of March 31, 2017		6,481,588		$	4.28

Schedule of shares vested, expected to vest and exercisable

	Shares		Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value
Vested and unvested expected to vest at March 31, 2017		9,326,234	$	3.44		5.9	$	—
Exercisable at March 31, 2017		6,481,588	$	4.28		4.5	$	—

Schedule of restricted stock activity

Restricted Stock	Number of Shares			Weighted Average Grant Date Fair Value
Unvested as of December 31, 2016		29,276		$	2.51
Vested		(29,276	)		2.51
Unvested as of March 31, 2017		—		$	—