Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 320,482	$ 173,415
Short-term investments	400,530	555,231
Receivable from collaboration partners ($1,324 and $943 from a related party)	1,575	1,049
Accrued interest receivable	1,400	649
Prepaid expenses and other current assets	21,967	5,471
Total current assets	745,954	735,815
Long-term investments	84,096	6,440
Property and equipment, net	23,806	10,807
Right-of-use assets	36,137	12,781
Restricted cash	3,005	203
Other long-term assets	5,775	6,246
Total assets	898,773	772,292
Current liabilities:
Accounts payable	16,957	15,682
Accrued research and development expenses	28,756	18,307
Other accrued liabilities	9,706	9,543
Deferred revenue, current ($67,571 and $67,571 to a related party)	74,571	74,571
Other current liabilities	380	3,566
Total current liabilities	130,370	121,669
Deferred revenue, noncurrent ($102,386 and $117,808 to a related party)	103,908	122,830
Operating lease liabilities, noncurrent	49,741	15,243
Other long-term liabilities ($9,703 and $9,703 to a related party)	10,199	10,246
Total liabilities	294,218	269,988
Commitments (Note 11)
Stockholders’ equity:
Preferred stock, $0.0001 par value, 10,000,000 shares authorized as of June 30, 2021 and December 31, 2020; no shares issued and outstanding as of June 30, 2021 and December 31, 2020	0	0
Common stock, $0.0001 par value, 400,000,000 shares authorized as of June 30, 2021 and December 31, 2020; 71,374,059 and 65,114,685 shares issued and outstanding as of June 30, 2021 and December 31, 2020, respectively. Shares outstanding includes 1,331,269 and 1,422,784 shares issued but subject to vesting as of June 30, 2021 and December 31, 2020, respectively	7	6
Additional paid-in capital	1,081,341	830,438
Accumulated deficit	(476,747)	(328,184)
Accumulated other comprehensive (loss) income	(46)	44
Total stockholders’ equity	604,555	502,304
Total liabilities and stockholders’ equity	$ 898,773	$ 772,292