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 income (loss)	$ 69,582	$ (13,534)
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Depreciation and amortization	180	126
Stock-based compensation	4,193	2,584
Change in operating lease right-of-use assets	2	6
Changes in operating assets and liabilities:
Grants receivable	(684)	(1,149)
Research and development tax credits receivable	889	191
Refundable Income Taxes	7,544
Prepaid expenses and other current assets	1,810	493
Accounts payable	5,465	2,348
Accrued expenses and other liabilities	(3,062)	(2,115)
Income tax payable	20,107
Deferred income	194	(3,740)
Deferred revenue	(152,522)
Uncertain tax benefit	22,300
Net cash used in operating activities	(24,002)	(14,790)
Cash flows from investing activities
Purchase of property and equipment	(227)	(88)
Purchase of other assets	(96)	(3)
Net cash used in investing activities	(323)	(91)
Cash flows from financing activities
Proceeds from issuance of common stock upon exercise of options	333	667
Net cash provided by financing activities	333	667
Effects of exchange rate changes on cash, cash equivalents and restricted cash	(563)	(717)
Net decrease in cash, cash equivalents and restricted cash	(24,555)	(14,931)
Cash, cash equivalents and restricted cash at beginning of period	848,835	336,454
Cash, cash equivalents and restricted cash at end of period	824,280	321,523
Non-cash investing and financing activities
Capital expenditure included in accounts payable	184	0
Operating lease liabilities arising from obtaining right-of-use assets	199	3,206
Supplemental disclosure of cash flows
Cash paid for taxes	$ 0	$ 0