CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating activities:
Net loss	$ (15,443,000)	$ (18,715,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	31,000	106,000
Noncash interest expense	2,303,000	1,253,000
Share-based compensation expense	1,848,000	1,791,000
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	1,846,000	(1,568,000)
Other assets	78,000	4,000
Accounts payable	(913,000)	4,071,000
Accrued expense	(1,067,000)	(2,242,000)
Other liabilities	(68,000)	(3,000)
Cash used in operating activities	(11,385,000)	(15,303,000)
Investing activities:
Purchases of short-term investments	(15,651,000)	(6,931,000)
Proceeds from sales of short-term investments	25,660,000	20,000,000
Purchase of property and equipment	(13,000)	(186,000)
Cash provided by investing activities	9,996,000	12,883,000
Financing activities:
Proceeds from the sale of common stock, net of issuance costs	1,117,000	0
Proceeds from exercise of stock options	58,000	235,000
Cash provided by financing activities	1,175,000	235,000
Net decrease in cash and cash equivalents	(214,000)	(2,185,000)
Cash and cash equivalents at beginning of period	19,859,000	15,872,000
Cash and cash equivalents at end of period	19,645,000	13,687,000
Supplemental schedule of non-cash financing activities:
Unrealized loss on marketable securities	$ (47,000)	$ (2,000)