Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Cash flows from operating activities:
Net loss	$ (2,635)	$ (4,784)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	16	40
Amortization of operating lease right-of-use assets	65
Loss on impairment of fixed assets		48
Derivatives loss		12
Non-cash interest expense	1	1
Gain on sale of asset		(25)
Common stock issued to 401(k) plan		6
Share-based compensation expense	67	306
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(674)	(443)
Accounts payable	173	240
Operating lease liability	26
Accrued expenses and other liabilities	(397)	906
Net cash used in operating activities	(3,358)	(3,693)
Cash flows from investing activities:
Disposals of property and equipment		25
Net cash provided by investing activities		25
Cash flows from financing activities:
Proceeds from issuance of stock under ESPP	1	3
Repayment of loan payable	(100)	(110)
Repurchase of warrants		(14)
Proceeds from issuance of common stock, net of issuance costs		2,510
Net cash (used in) provided by financing activities	(99)	2,389
Decrease in cash and cash equivalents and restricted cash	(3,457)	(1,279)
Cash, cash equivalents and restricted cash at beginning of period	16,774	13,271	$ 13,271
Cash, cash equivalents and restricted cash at end of period	13,317	11,992	$ 16,774
Supplemental disclosure of cash flow information and non-cash investing and financing activities:
Cash paid for interest	1	14
Right-of-use assets and lease liability recorded upon adoption of ASC 842	$ 1,475
Non-cash issuance of common stock for warrants		$ 287