Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net loss	$ (19,942)	$ (13,242)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	979	977
Non-cash lease expense	151	137
Stock-based compensation expense	1,952	733
Change in fair value of stock warrants	(257)	(7,221)
Change in fair value of contingent consideration	2,047	3,426
Change in operating assets and liabilities:
Prepaid expenses, other current assets and other assets	83	(35)
Other assets	(40)
Accounts payable	(153)	1,619
Accrued compensation	(353)	237
Accrued clinical trial site costs	138	1,445
Operating lease liabilities	(168)	(7)
Other liabilities	62	(262)
Net cash used in operating activities	(15,501)	(12,193)
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, net of costs		53,950
Tax withholding payments for net share-settled equity awards	(120)
Proceeds from stock option exercises		17
Principal paid on finance lease liabilities	(3)	(8)
Net cash provided by (used in) financing activities	(123)	53,959
Net increase (decrease) in cash and cash equivalents	(15,628)	41,766
Cash and cash equivalents, beginning of period	49,224	20,733
Cash and cash equivalents, end of period	33,596	$ 62,499
Supplemental disclosure of non-cash activities
Right-of-use assets obtained in exchange for operating lease obligations	581
Deferred financing costs included in accounts payable	$ 12