CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net loss	$ (32,900)	$ (23,138)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	47	49
Change in right of use assets.	729
Stock-based compensation expense	3,732	3,469
Change in fair value of restricted stock liability	159
Change in fair value of warrant liability		(7,284)
Changes in operating assets and liabilities:
Prepaid expenses and other assets	302	(297)
Deferred tax assets	(3)	20
Research and development incentive receivable	643	780
Accounts payable and accrued expenses	1,084	368
Lease liability	(695)
Net cash used in operating activities	(26,902)	(26,033)
Cash flows from investing activities:
Purchases of property and equipment	(100)
Proceeds from sale of property and equipment	15
Net cash used in investing activities	(85)
Cash flows from financing activities:
Proceeds from the issuance of common stock, net of underwriter commissions and discounts	12,331	15,034
Proceeds from issuance of common stock from ATM sales	1,923
Proceeds from issuance of common stock in connection with July 2019 Lincoln Park Capital Registered Offering Purchase Agreement	1,000
Proceeds from the exercise of common stock warrants		1,217
Proceeds from the exercise of stock options		14
Payment of deferred offering costs	(437)	(359)
Net cash provided by financing activities	14,817	15,906
Effect of exchange rate changes on cash and cash equivalents	(223)	674
Net decrease in cash and cash equivalents	(12,393)	(9,453)
Cash and cash equivalents at beginning of period	16,284	25,737
Cash and cash equivalents at end of period	3,891	16,284
Supplemental disclosure of non-cash financing activities:
Reduction in fair value of warrant liability as a result of exercise of common stock warrants		1,130
Reclassification of 2017 Warrants from liability to equity	3,448
Dividend attributable to down round feature of warrants	359
Offering costs included in accounts payable and accrued expenses	444	$ 41
Right-of-use asset recorded upon adoption of ASU 2016-02	1,755
Lease liability recorded upon adoption of ASU 2016-02	1,720
Accrued rent reclassified upon adoption of ASU 216-02	$ 35