Condensed Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Operating activities:
Net loss	$ (10,009)	$ (6,180)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	12	8
Amortization of license agreement	70	73
Stock-based compensation	352	638
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(153)	(24)
Accounts payable and accrued expenses	423	614
Net cash used in operating activities	(9,305)	(4,871)
Investing activities:
Purchases of furniture, fixtures, equipment and other assets	(6)
Net cash used in investing activities	(6)
Financing activities:
Proceeds from issuance of preferred stock, net of issuance costs		6,334
Proceeds from issuance of common stock, net of issuance costs	25,681	1,936
Proceeds from exercise of warrants into common stock, net of issuance costs	9,512	432
Net cash provided by financing activities	35,193	8,702
Increase in cash and cash equivalents	25,882	3,831
Cash at beginning of period	7,005	4,946
Cash at end of period	32,887	8,777
Non-Cash investing and financing activities:
Conversion of preferred stock to common stock		2,198
Non-cash deemed dividend to preferred stock		$ 4,799