Condensed Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Operating activities:
Net loss	$ (6,559)	$ (3,534)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	8	5
Amortization of license agreement	46	49
Stock-based compensation	222	274
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(341)	(126)
Accounts payable and accrued expenses	697	(10)
Net cash used in operating activities	(5,927)	(3,342)
Financing activities:
Proceeds from issuance of preferred stock, net of issuance costs		4,192
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
Net cash provided by financing activities	35,193	6,128
Increase (decrease) in cash and cash equivalents	29,266	2,786
Cash at beginning of period	7,005	4,946
Cash at end of period	36,271	7,732
Non-Cash investing and financing activities:
Conversion of preferred stock to common stock	$ 0	$ 364