CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities:
Net loss	$ (18,789)	$ (28,754)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	208	288
Stock-based compensation expense	2,346	2,675
Revaluation of contingent consideration	(1,200)	16,439
Changes in operating assets and liabilities:
Accounts receivable	(10)	(45)
Prepaid expenses and other assets	188	(2,250)
Accounts payable	(1,865)	1,842
Accrued expenses	(1,847)	(2,427)
Net cash used in operating activities	(20,969)	(12,232)
Cash flows from investing activities:
Purchases of property and equipment	(164)
Purchases of marketable securities	(14,558)	(85,814)
Proceeds from sales and maturities of marketable securities	44,654	10,500
Net cash provided by (used in) investing activities	29,932	(75,314)
Cash flows from financing activities:
Proceeds from issuance of common stock in connection with public offerings, net of issuance costs		103,348
Restricted stock unit employee tax withholdings	(7)	(3,014)
Proceeds from exercise of employee stock options and the issuance of stock	37	416
Net cash provided by financing activities	30	100,750
Net increase in cash and cash equivalents	8,993	13,204
Cash and cash equivalents at beginning of period	27,349	22,063
Cash and cash equivalents at end of period	36,342	$ 35,267
Supplemental disclosure of non-cash investing and financing activities:
Additions to property and equipment included in accounts payable	$ 111