Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net loss	$ (11,830)	$ (23,423)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	57	91
Amortization of operating lease right-of-use assets	265
Loss on impairment of fixed assets		48
Warrant Modification	666	765
Derivatives loss		11,400
Gain on lease assignment		(603)
Common stock issued to 401(k) plan		6
Share-based compensation expense	268	618
Non-cash investment (income) expense, net	1	3
Changes in operating assets and liabilities:
Prepaid expenses	267	77
Other assets	(123)	(985)
Accounts payable	127	(173)
Operating lease liability	(144)
Accrued expenses and other liabilities	132	(136)
Net cash used in operating activities	(10,314)	(12,312)
Cash flows from investing activities:
Purchases of property and equipment	(12)	(65)
Net cash used in investing activities	(12)	(65)
Cash flows from financing activities:
Proceeds from issuance of stock under ESPP	1	4
Proceeds from exercise of warrants		131
Repayment of loan payable	(100)	(752)
Repurchase of warrants		(14)
Proceeds from issuance of common stock and warrants, net of commissions and issuance costs	367	16,511
Net cash (used in) provided by financing activities	268	15,880
Decrease in cash and cash equivalents and restricted cash	(10,058)	3,503
Cash, cash equivalents and restricted cash at beginning of period	16,774	13,271
Cash, cash equivalents and restricted cash at end of period	6,716	16,774
Supplemental disclosure of cash flow information and non-cash investing and financing activities:
Cash paid for interest	1	44
Non-cash issuance of common stock for warrants		287
Fair value of derivative warrant liability reclassified to additional paid-in capital		$ 25,327
Right-of-use assets and lease liability recorded upon adoption of ASC 842	1,475
Fair value of warrants issued in connection with 2019 Offering	$ 59