Unaudited Condensed Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Operating activities
Net loss	$ (14,464)	$ (11,538)
Adjustments to reconcile net loss to net cash used for operating activities:
Share-based compensation expense	6,595	8,568
Depreciation expense	10	3
Changes in operating assets and liabilities:
Restricted cash	0	(37)
Prepaid expenses and other current assets	(110)	(22)
Accounts payable and accrued expenses	562	322
Accrued payroll and related expenses	(68)	39
Net cash used for operating activities	(7,475)	(2,665)
Investing activities:
Purchase of equipment and furnishings	(86)	(40)
Net cash used for investing activities	(86)	(40)
Financing activities:
Net proceeds from the issuance of common stock	53,063	6,750
Proceeds from the issuance of Series F Convertible Preferred Stock	0	3,250
Net cash provided by financing activities	53,063	10,000
Net increase in cash and cash equivalents:	45,502	7,295
Cash and cash equivalents at beginning of period	8,629	3,405
Cash, cash equivalents at end of period	54,131	10,700
Non-cash investing and financing activity
Redemption of Series D-12 Convertible Preferred Stock and Series C-22 Convertible Preferred Stock Warrants	0	4,568
Dividends paid in shares of Series C-12 and C-22 Convertible Preferred Stock	0	801
Conversion of Series C-1 and D-1 Preferred Stock into Common Stock [Member]
Non-cash investing and financing activity
Conversion of stock	3,099	58
Exchange of Series C-2 for Series C-1 Preferred Stock [Member]
Non-cash investing and financing activity
Conversion of stock	0	557
Conversion of Series F Preferred Stock into Common Stock [Member]
Non-cash investing and financing activity
Conversion of stock	$ 452	$ 0