Condensed Statements of Operations and Comprehensive Loss (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
OPERATING EXPENSES:
Research and development	$ 10,618	$ 16,240	$ 20,335	$ 33,527
General and administrative	3,070	1,444	5,209	3,022
Loss from operations	(13,688)	(17,684)	(25,544)	(36,549)
OTHER (EXPENSE) INCOME:
Other income (expense) , net	1,727	(1,184)	(506)	10,072
Loss on retirement of note payable	(203)		(203)
Interest income	5	14	7	16
Interest expense	(450)	(658)	(851)	(1,356)
NET LOSS	(12,609)	(19,512)	(27,097)	(27,817)
OTHER COMPREHENSIVE LOSS, NET OF TAX:
Unrealized gain from marketable securities	1	3	1	3
COMPREHENSIVE LOSS	(12,608)	(19,509)	(27,096)	(27,814)
LOSS ATTRIBUTABLE TO COMMON STOCKHOLDERS - BASIC AND DILUTED (Note 11):	$ (16,640)	$ (23,880)	$ (36,097)	$ (35,767)
LOSS PER SHARE:
Basic (in dollars per share)	$ (2.22)	$ (62.59)	$ (9.11)	$ (93.89)
Diluted (in dollars per share)	$ (2.22)	$ (62.59)	$ (9.11)	$ (93.89)
WEIGHTED AVERAGE SHARES:
Basic (in shares)	7,500,148	381,525	3,962,559	380,942
Diluted (in shares)	7,500,148	381,525	3,962,559	380,942