Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 284,803	$ 848,537
Short-term investments (amortized cost of $328,405)	328,359	0
Grants receivable	1,001	4,022
Research and development tax credits receivable	0	524
Refundable income taxes	1,434	7,544
Prepaid expenses and other current assets	12,701	14,086
Total current assets	628,298	874,713
Property and equipment, net	2,121	2,072
Long-term investments (amortized cost of $118,330)	118,225	0
Research and development tax credits receivable, net of current portion	1,128	2,004
Restricted cash	235	298
Right of use assets	4,652	5,329
Other assets	332	296
Total assets	754,991	884,712
Current liabilities:
Accounts payable	7,662	5,145
Accrued expenses and other current liabilities	19,727	17,157
Deferred income	1,180	827
Deferred revenue	12,595	280,225
Lease liabilities	836	770
Total current liabilities	42,000	304,124
Grants repayable	6,622	6,164
Lease liabilities, net of current portion	3,837	4,571
Unrecognized tax benefits	39,200	17,000
Other noncurrent liabilities	0	33
Total liabilities	91,659	331,892
Commitments and contingencies (Note 10)
Stockholders’ equity (deficit):
Common stock, $0.001 par value, 150,000,000 shares authorized at December 31, 2022 and 2021, respectively; 35,611,219 and 35,466,001 shares issued and outstanding at December 31, 2022 and 2021, respectively	36	35
Additional paid-in capital	435,665	413,180
Accumulated other comprehensive (loss)	(9,644)	(1,018)
Retained earnings	237,275	140,623
Total stockholders' equity	663,332	552,820
Total liabilities and stockholders' equity	$ 754,991	$ 884,712