Consolidated Statements of Cash Flow (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating activities:
Net loss	$ (8,277)	$ (8,079)	$ (9,653)
Adjustments to reconcile net loss to net cash used in operating activities:
Change in fair value of warrants		(6)	(2,222)
Depreciation	12	29	53
Amortization of license agreement	98	98	97
Stock-based compensation	679	511	851
Changes in operating assets and liabilities:
Restricted cash	20		55
Prepaid expenses and other current assets	117	464	(9)
Accounts payable and accrued expenses	350	(1,352)	(956)
Net cash used in operating activities	(7,001)	(8,335)	(11,784)
Investing activities:
Purchases of furniture, fixtures, equipment and other assets	(35)	(8)
Net cash used in investing activities	(35)	(8)
Financing activities:
Proceeds from issuance of preferred stock, net of issuance costs	6,295
Proceeds from issuance of common stock, net of issuance costs	1,936	3,317	17,146
Proceeds from exercise of Series B warrants into common stock, net of issuance costs	864
Proceeds from exercise of employee stock plans			8
Net cash provided by financing activities	9,095	3,317	17,154
Increase (decrease) in cash and cash equivalents	2,059	(5,026)	5,370
Cash at beginning of period	4,946	9,972	4,602
Cash at end of period	7,005	4,946	9,972
Non-Cash investing and financing activities:
Conversion of preferred stock to common stock	7,998
Redemption of preferred stock in connection with the private placement	2,802
Non-cash deemed dividend to preferred stock	4,799
Issuance of common stock in connection with the private placement warrant exchange			5,383
Issuance of common stock for the initial commitment fee in connection with the LPC purchase agreement			314
Reclassification of CEFF warrants to equity from derivative liability due to warrant exchange			$ 3