Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities:
Net loss	$ (5,724)	$ (8,954)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	492	489
Non-cash lease expense	71	76
Stock-based compensation expense	644	1,095
Change in fair value of stock warrants	(27)	(201)
Change in fair value of contingent consideration	(858)	(987)
Other non-cash reconciling items	(2)
Change in operating assets and liabilities:
Prepaid expenses, other current assets and other assets	114	98
Accounts payable	(1,046)	1,180
Accrued compensation	(130)	(594)
Accrued clinical trial site costs	101	351
Operating lease liabilities	(34)	(82)
Other liabilities	37	41
Net cash used in operating activities	(6,362)	(7,488)
Cash flows from investing activities:
Purchases of property and equipment		(4)
Net cash used in investing activities		(4)
Cash flows from financing activities:
Proceeds from sale of common stock and pre-funded warrants, net of costs	14,048
Tax withholding payments for net share-settled equity awards	(16)	(120)
Principal paid on finance lease liabilities		(5)
Net cash provided by (used in) financing activities	14,032	(125)
Net increase (decrease) in cash and cash equivalents	7,670	(7,617)
Cash and cash equivalents, beginning of period	21,304	49,224
Cash and cash equivalents, end of period	28,974	$ 41,607
Supplemental disclosure of non-cash activities
Unpaid costs for issuing common stock and pre-funded warrants	$ 282