Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities:
Net loss	$ (2,901)	$ (5,007)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	129	(49)
Warrant revaluation expense (income)	(235)	46
Derivative revaluation expense	63	312
Depreciation and amortization of long lived assets	101	91
Loss on disposal or impairment of property and equipment	0	30
Decrease (increase) in operating assets:
Prepaid expenses and other current assets	(12)	(51)
Other assets	0	(34)
Increase (decrease) in operating liabilities:
Accounts payable	23	(55)
Related party payable	(1,929)	567
Accrued expenses and deferred rent	(190)	(787)
Accrued interest payable	190	183
Net cash used in operating activities	(4,761)	(4,754)
Cash flows from investing activities:
Purchase of property and equipment	(35)	(87)
Net cash used in investing activities	(35)	(87)
Cash flows from financing activities:
Proceeds from 2017 Series A Preferred Stock Offering, (net of offering costs of $377)	0	7,886
Payment of deferred offering costs	(444)	0
Proceeds from conversion of pre-funded warrants	24	0
Net cash provided by (used in) financing activities	(420)	7,886
Effect of exchange rate changes on cash balances	0	0
Net increase (decrease) in cash and cash equivalents	(5,216)	3,045
Cash and cash equivalents, beginning of period	17,417	17,515
Cash and cash equivalents, end of period	12,201	20,560
Supplemental disclosures of cash flow information:
Property and equipment in accounts payable	33	13
Offering costs in accounts payable and accrued expenses	0	263
Reduction of warrant liability upon cashless exercise of warrants	0	41
Dividend paid in-kind to preferred stockholders	82	20
Deemed dividend on preferred stock	$ 121	$ 3,734