Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net loss	$ (4,532)	$ (4,603)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	26	23
Amortization of operating lease right-of-use assets	153	139
Share-based compensation expense	147	115
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(368)	(331)
Accounts payable	129	(424)
Operating lease liability	(157)	(143)
Accrued expenses and other liabilities	(336)	(463)
Net cash used in operating activities	(4,938)	(5,687)
Cash flows from investing activities:
Purchases of property and equipment		(23)
Net cash used in investing activities		(23)
Cash flows from financing activities:
Proceeds from exercise of warrants	8,509	343
Proceeds from issuance of common stock and warrants, net of commissions and issuance costs		8,592
Net cash provided by financing activities	8,509	8,935
Increase in cash and cash equivalents and restricted cash	3,571	3,225
Cash, cash equivalents and restricted cash at beginning of period	19,603	6,716
Cash, cash equivalents and restricted cash at end of period	23,174	9,941
Supplemental disclosure of cash flow information and non-cash investing and financing activities:
Fair value of warrants issued in connection with the financing activities		$ 5,907
Increase in operating right-of-use assets and liabilities related to lease modifications	$ 143