INCOME TAXES (Tables)

12 Months Ended

Dec. 31, 2016

INCOME TAXES

Schedule of components of the net deferred tax asset

The components of the net deferred tax asset with the approximate income tax effect of each type of carryforward, credit and temporary differences are as follows:

	December 31,
(In thousands)	2016		2015
Deferred tax assets:
Operating loss carryforwards	$	244,465	$	189,007
Tax credit carryforwards		19,271		17,947
Other temporary differences		14,176		8,146
Tax assets before valuation allowance		277,912		215,100
Less—Valuation allowance		(277,912)		(215,100)
Net deferred taxes	$	—	$	—

Schedule of differences between the effective income tax rate and the statutory tax rate

	December 31,
	2016		2015		2014
U.S. Federal statutory rate	35.0	%	35.0	%	34.0	%
State taxes	2.4		2.1		5.5
Federal and state tax rate changes	0.6		(1.7)		—
Foreign tax rate differential	(0.4)		—		—
Research and development tax credits	0.9		0.9		(1.1)
Stock-based compensation expense	(0.6)		(0.6)		(0.5)
Other adjustments	(0.3)		(0.9)		(0.8)
Valuation allowance	(37.6)		(34.8)		(37.1)
Effective tax rate	0.0	%	0.0	%	0.0	%