Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating activities
Net loss	$ (7,351)	$ (2,911)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	45	45
Share-based compensation expense	1,154	1,001
Gain on extinguishment of debt	(998)
Non-cash interest expense		10
Accretion of debt discount		21
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	279	49
Other assets and liabilities	(36)	68
Accounts payable and accrued liabilities	1,348	(1,086)
Net cash used in operating activities	(5,559)	(2,803)
Investing activities
Acquisition of property and equipment		(55)
Net cash used in investing activities		(55)
Financing activities
Proceeds from registered direct offering, net of issuance costs	11,078
Proceeds from at-the-market sales agreement, net of issuance costs	3,249	1,193
Proceeds from exercise of stock options	38
Proceeds from shares issued under employee stock purchase plan	54
Net cash provided by financing activities	14,419	1,193
Net increase (decrease) in cash, cash equivalents and restricted cash	8,860	(1,665)
Cash, cash equivalents and restricted cash, beginning of period	17,647	22,955
Cash, cash equivalents and restricted cash, end of period	26,507	21,290
Supplemental disclosure of noncash financing activities
Forgiveness of PPP Loan and accrued interest	998
Reconciliation of cash, cash equivalents and restricted cash
Cash and cash equivalents	26,147	20,930
Restricted cash	360	360
Cash, cash equivalents and restricted cash at end of period	$ 26,507	$ 21,290