STOCK-BASED COMPENSATION AND STOCK PLANS (Tables)

6 Months Ended

Jun. 30, 2017

Compensation and Retirement Disclosure [Abstract]

Schedule of stock-based compensation expense

	Three Months Ended June 30,				Six Months Ended June 30,
	2017		2016		2017		2016
Research and development	$	74	$	109	$	204	$	299
General and administrative		212		312		625		716
Total stock-based compensation expense	$	286	$	421	$	829	$	1,015

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		2,537,500			1.19
Exercised		—			—
Cancelled		(479,105	)		4.96
Outstanding as of June 30, 2017		10,773,443		$	3.06
Exercisable as of June 30, 2017		6,484,316		$	4.16

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 June 30, 2017		10,566,460	$	3.06		6.2	$	479
Exercisable at June 30, 2017		6,484,316	$	4.16		4.3	$	37