Condensed Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Operating activities:
Net loss	$ (6,180)	$ (6,404)
Adjustments to reconcile net loss to net cash used in operating activities:
Change in fair value of warrants		(5)
Depreciation	8	12
Amortization of license agreement	73	74
Stock-based compensation	638	429
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(24)	434
Accounts payable and accrued expenses	614	(1,003)
Net cash used in operating activities	(4,871)	(6,463)
Financing activities:
Proceeds from issuance of preferred stock, net of issuance costs	6,334
Proceeds from issuance of common stock, net of issuance costs	1,936	2,794
Proceeds from exercise of Series B warrants into common stock, net of issuance costs	432
Net cash provided by financing activities	8,702	2,794
Increase (decrease) in cash and cash equivalents	3,831	(3,669)
Cash at beginning of period	4,946	9,972
Cash at end of period	8,777	6,303
Non-Cash investing and financing activities:
Conversion of preferred stock to common stock	2,198
Non-cash deemed dividend to preferred stock	$ 4,799