Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current Assets:
Cash and cash equivalents	$ 334,736	$ 160,020
Marketable securities	463,531	437,351
Accounts receivable ($0.2 million and $0 million from related party)	2,491	2,130
Prepaid expenses and other current assets	14,016	17,016
Total current assets	814,774	616,517
Marketable securities - noncurrent	350,451
Property and equipment, net	19,946	15,943
Operating lease right-of-use assets	81,788	39,114
Equity method investment	62,837
Other assets	5,165	4,748
Total Assets	1,334,961	676,322
Current Liabilities:
Accounts payable	7,470	10,460
Accrued expenses	24,633	25,554
Current portion of operating lease liability	8,705	5,696
Current portion of deferred revenue ($34.2 million and $0 million from related party)	56,759	22,544
Total current liabilities	97,567	64,254
Deferred revenue, net of current portion ($28.5 million and $0 million from related party)	63,023	51,387
Long-term operating lease liability	67,273	33,609
Commitments and contingencies (Note 6)
Stockholders’ Equity:
Common stock, $0.0001 par value; 120,000,000 shares authorized; 74,342,178 and 66,234,056 shares issued and outstanding at September 30, 2021 and December 31, 2020, respectively	7	7
Additional paid-in capital	1,729,029	962,173
Accumulated other comprehensive (loss)/income	(174)	1
Accumulated deficit	(621,764)	(435,109)
Total stockholders’ equity	1,107,098	527,072
Total Liabilities and Stockholders’ Equity	$ 1,334,961	$ 676,322