Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Cash flows used in operating activities:
Net loss	$ (58,339)	$ (20,308)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	86	41
Amortization of patents and licenses	114	75
Impairment of patents	748	10
Impairment of clinical trial supplies	8,190
Impairment of prepaid expenses	465
Accrued final bank fee	65	33
Amortization of debt discount	72	37
Amortization of debt issuance costs	8	100
Change in fair value of warrant liability	(18)	(56)
Stock-based compensation	1,641	346
Loss on disposal of property and equipment	15
Other		64
Changes in operating assets and liabilities:
Prepaid expenses	435	(4,832)
Other assets	(7,496)	(244)
Other non-current assets	4,686	(1,855)
Accounts payable	2,548	221
Accrued expenses	2,735	4,242
Net cash used in operating activities	(44,045)	(22,126)
Cash flows used in investing activities:
Change in restricted cash	(1,000)
Purchase of property and equipment	(309)	(77)
Patent and license acquisition costs	(389)	(415)
Proceeds received from sale of patents		100
Net cash used in investing activities	(1,698)	(392)
Cash flows from financing activities:
Proceeds from borrowings on bank loan		4,500
Repayment of borrowings on bank loan	(500)	(4,500)
Payment of bank origination fee		(85)
Payment of debt issuance costs		(57)
Proceeds from issuance of common stock, net of underwriting discounts and fees	76,723	43,418
Payment of offering costs	(541)	(2,231)
Proceeds from sale of preferred stock, net of issuance costs		10,163
Proceeds from issuance of common stock from exercise of options and warrants	53
Proceeds from exercise of warrants		2
Net cash provided by financing activities	75,735	51,210
Net increase in cash and cash equivalents	29,992	28,692
Cash and cash equivalents, beginning of period	30,688	14,764
Cash and cash equivalents, end of period	60,680	43,456
Supplemental disclosures of cash flow information:
Cash paid for interest	248	465
Supplemental disclosure of non-cash investing and financing activities:
Exchange of common stock for convertible preferred stock, net of issuance costs	24,832
Stock issued for cash held in escrow		5,155
Series F Convertible Preferred Stock [Member]
Supplemental disclosure of non-cash investing and financing activities:
Fair value of Series F Preferred Stock beneficial conversion feature	14,840
Accretion of deemed dividend on Series F Convertible Preferred Stock	$ (14,840)