Consolidated Statements of Cash Flows - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating activities:
Net loss	$ (5,495,000)	$ (5,078,000)
Adjustments required to reconcile net loss to net cash used in operating activities:
Depreciation	281,000	295,000
Stock-based compensation	842,000	1,044,000
Non-cash interest expense	62,000	159,000
Payment of accreted interest for deferred consideration for asset acquisition	(586,000)
Changes in operating assets and liabilities:
Award receivable	(564,000)	(1,000,000)
Accounts payable and accrued liabilities	(409,000)	(195,000)
Accrued compensation	330,000	(114,000)
Operating lease right-of-use asset and liability, net	49,000	(122,000)
Deferred award liability		859,000
Prepaid expenses and other current assets	15,000	(80,000)
Net cash used in operating activities	(5,475,000)	(4,232,000)
Investing activities:
Purchases of property and equipment	(298,000)	(104,000)
Net cash (used in) provided by investing activities	(298,000)	(104,000)
Financing activities:
Principal payment of deferred consideration for asset acquisition	(1,414,000)	(1,000,000)
Proceeds from sale of common stock, net of offering costs	19,548,000	23,331,000
Proceeds from exercise of warrants and stock options	445,000	81,000
Net cash provided by financing activities	18,579,000	22,412,000
Net increase (decrease) in cash, cash equivalents and restricted cash	12,806,000	18,076,000
Cash, cash equivalents and restricted cash, beginning of period	10,849,000	6,733,000
Cash, cash equivalents and restricted cash, end of period	23,655,000	24,809,000
Supplemental schedule of non-cash investing and financing activities:
Unpaid offering costs	185,000	471,000
Property and equipment included in accounts payable	$ 51,000	$ 9,000