Consolidated Balance Sheets - USD ($)	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 280,119,000	$ 447,646,000
Investments	677,954,000	230,415,000
Accounts receivable	403,000	75,000,000
Contract asset	4,537,000	7,654,000
Prepaid expenses and other current assets	13,229,000	9,385,000
Total current assets	976,242,000	770,100,000
Property and equipment, net	6,543,000	6,250,000
Operating lease assets	20,780,000	22,579,000
Restricted cash	2,578,000	878,000
Intangible asset	2,300,000
Other assets		22,000
Total assets	1,008,443,000	799,829,000
Current liabilities:
Accounts payable	8,276,000	6,351,000
Accrued expenses and other current liabilities	13,953,000	5,760,000
Operating lease liabilities, current	1,844,000	1,521,000
Deferred revenue	248,000
Total current liabilities	24,321,000	13,632,000
Operating lease liabilities, net of current portion	21,056,000	22,901,000
Restricted stock liability		3,000
Contingent consideration liability	50,258,000	0
Other liabilities	15,000,000
Total liabilities	110,635,000	36,536,000
Commitments and contingencies (Note 13)
Stockholders' equity
Undesignated preferred stock, $0.001 par value, 10,000,000 shares authorized as of December 31, 2021 and December 31, 2020; no shares issued and outstanding at December 31, 2021 and December 31, 2020	0	0
Common stock, $0.001 par value; 150,000,000 shares authorized at December 31, 2021 and December 31, 2020, respectively; 108,210,318 and 89,991,324 shares issued at December 31, 2021 and December 31, 2020, respectively; 108,210,318 and 89,906,835 shares outstanding at December 31, 2021 and December 31, 2020, respectively	109,000	90,000
Additional paid-in capital	1,666,887,000	1,167,367,000
Accumulated other comprehensive (loss) income	(1,088,000)	64,000
Accumulated deficit	(768,100,000)	(404,228,000)
Total stockholders' equity	897,808,000	763,293,000
Total liabilities and stockholders' equity	$ 1,008,443,000	$ 799,829,000