Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net loss	$ (8,654)	$ (19,140)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	393	194
Warrant revaluation expense (income)	(591)	4,742
Derivative revaluation income	(266)	(287)
Depreciation and amortization of long lived assets	302	282
Amortization of debt discount	0	86
Loss on disposal or impairment of property and equipment	0	40
Decrease (increase) in operating assets:
Prepaid expenses and other current assets	191	248
Other assets	38	4
Increase (decrease) in operating liabilities:
Accounts payable	258	132
Related party payable	(2,240)	789
Accrued expenses and deferred rent	(223)	(524)
Accrued interest payable	575	555
Net cash used in operating activities	(10,217)	(12,879)
Cash flows from investing activities:
Purchase of property and equipment	(155)	(348)
Net cash used in investing activities	(155)	(348)
Cash flows from financing activities:
Proceeds from 2017 Series A Preferred Stock Offering, (net of offering costs of $377)	0	7,623
Payment of deferred offering costs	(444)	0
Proceeds from conversion of pre-funded warrants	24	0
Proceeds from conversion of common warrants	499	0
Net cash provided by financing activities	9,066	7,623
Effect of exchange rate changes on cash balances	0	0
Net increase (decrease) in cash and cash equivalents	(1,306)	(5,604)
Cash and cash equivalents, beginning of period	17,417	17,515
Cash and cash equivalents, end of period	16,111	11,911
Supplemental disclosures of cash flow information:
Property and equipment in accounts payable	0	29
Offering costs in accounts payable and accrued expenses	72	0
Reduction of warrant liability upon cashless exercise of warrants	0	41
Reduction in accrued interest payable upon cashless exercise of promissory notes	0	3
Reduction in derivative liability upon cashless exercise of promissory notes	0	6
Cashless exercise of promissory notes	0	85
Dividend paid in-kind to preferred stockholders	250	182
Deemed dividend on preferred stock	377	3,981
May 2018 Registered Direct Offering
Cash flows from financing activities:
Proceeds from Registered Direct Offering, (net of offering costs)	5,360	0
July 2018 Registered Direct Offering
Cash flows from financing activities:
Proceeds from Registered Direct Offering, (net of offering costs)	$ 3,627	$ 0