CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOW - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net loss	$ (29,911)	$ (23,656)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,539	2,313
Amortization and premium of marketable securities, net	(173)	(335)
Gain on sale or disposal of assets	(24)	(20)
Intangible Asset Impairment		3,500
Loss (gain) on fair value remeasurement of contingent consideration	741	(4,898)
Non-Cash Income Tax Benefit		(228)
Stock-based compensation expense	2,784	1,408
Changes in operating assets and liabilities:
Accounts and other receivables	1,306	686
Prepaid and other current assets	(1,544)	(436)
Accounts payable and accrued expenses	(750)	(254)
Other liabilities	(3,982)	(1,412)
Net cash used in operating activities	(30,014)	(23,332)
Cash flows from investing activities:
Sales and maturities of marketable securities	116,000	47,000
Purchases of marketable securities	(85,739)	(132,439)
Acquisition of property and equipment	(710)	(1,145)
Proceeds from sale or disposal of assets	24	20
Net cash provided by (used in) investing activities	29,575	(86,564)
Cash flows from financing activities:
Net proceeds from stock issuances		166,667
Proceeds from issuance of stock from employee benefit plans	49	24
Issuance of Term Loan		2,962
Payment of Term Loan		(2,962)
Net cash provided by financing activities	49	166,691
Net (decrease) increase in cash and cash equivalents	(390)	56,795
Cash and cash equivalents at beginning of period	43,836	11,232
Cash and cash equivalents at end of period	$ 43,446	68,027
Non-cash investing activities
Accrued construction in progress		$ 22