Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net loss	$ (15,476,000)	$ (24,525,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	101,000	140,000
Stock-based compensation and 401(k) plan employer match	660,000	971,000
Fair value adjustment of common stock warrants		(223,000)
Amortization of prepaid interest	543,000	1,088,000
Changes in:
Prepaid expenses and other current assets	194,000	(92,000)
Accounts payable	2,231,000	3,101,000
Collaboration payable	(37,000)	1,226,000
Accrued expenses	(1,077,000)	(122,000)
Other liabilities		124,000
Net cash used in operating activities	(12,861,000)	(18,312,000)
Cash flows from investing activities:
Purchase of property and equipment	(24,000)	(149,000)
Net cash used in investing activities	(24,000)	(149,000)
Cash flows from financing activities:
Proceeds from Private Placement issuance of securities, net of expenses	8,789,000
Proceeds from ATM Program, net of expenses	1,036,000	69,000
Net cash provided by financing activities	9,825,000	69,000
Net increase/(decrease) in cash and cash equivalents	(3,060,000)	(18,392,000)
Cash, cash equivalents and restricted cash - beginning of year	5,813,000	38,947,000
Cash, cash equivalents and restricted cash - end of year	2,753,000	20,555,000
Supplementary disclosure of cash flows information:
Interest paid	$ 514,000	$ 61,000