Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 84,979	$ 89,641
Marketable securities	376,735	263,432
Prepaid expenses and other current assets	8,298	4,364
Total current assets	470,012	357,437
Property and equipment, net	30,583	33,852
Operating lease right-of-use assets	27,304	28,476
Restricted cash	1,472	1,472
Other assets	2,217	676
Total Assets	531,588	421,913
Current liabilities:
Accounts payable	1,370	278
Accrued clinical supply costs	9,320	6,706
Accrued liabilities	27,065	18,256
Deferred revenue, current portion	26,596	30,165
Operating lease liabilities, current portion	6,736	6,565
Total current liabilities	71,087	61,970
Deferred revenue, long-term portion	110,560	123,236
Operating lease liabilities, long-term portion	39,257	41,471
Other long-term liabilities	493	493
Total liabilities	221,397	227,170
Stockholders' equity:
Common stock, $0.0001 par value; 200,000,000 shares authorized as of September 30, 2020 and December 31, 2019	8	7
Additional paid-in capital	666,958	414,414
Accumulated other comprehensive income	1,094	142
Accumulated deficit	(357,869)	(219,820)
Total stockholders' equity	310,191	194,743
Total liabilities and stockholders’ equity	$ 531,588	$ 421,913