CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($)	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Cash flows from operating activities
Net loss	$ (17,428,000)	$ (14,164,000)
Adjustments to reconcile net loss to cash used in operating activities
Depreciation expense	18,000	16,000
Amortization expense - right-of-use leased assets - operating	212,000	199,000
Accretion of discount on investments	(24,000)	115,000
Stock-based compensation	1,316,000	1,110,000
Non-cash interest expense	218,000	263,000
Changes in operating assets and liabilities
Prepaid expenses and other assets	809,000	143,000
Accounts payable, accrued expenses and other liabilities	335,000	(2,568,000)
Net cash used in operating activities	(14,544,000)	(14,886,000)
Cash flows from investing activities
Purchases of property and equipment	(6,000)
Maturities of short-term investments	7,000,000	26,100,000
Purchases of short-term investments	(20,645,000)	(7,992,000)
Net cash provided by (used in) investing activities	(13,651,000)	18,108,000
Cash flows from financing activities
Principal payments on term loan	(5,000,000)
Proceeds from employee stock purchase plan	84,000
Proceeds from the exercise of vested stock options	21,000	9,000
Settlements of restricted stock units for tax withholding obligations		(81,000)
Net cash used in financing activities	(4,895,000)	(72,000)
Net increase (decrease) in cash, cash equivalents and restricted cash	(33,090,000)	3,150,000
Cash, cash equivalents and restricted cash at beginning of period	74,450,000	72,001,000
Cash, cash equivalents and restricted cash at end of period	41,360,000	75,151,000
Supplemental cash flow information
Interest paid	794,000	1,114,000
Taxes paid	$ 114,000	$ 125,000