CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Operating expenses:
Research and development	$ 61,674	$ 47,362	$ 278,654	$ 151,993
General and administrative	28,782	7,574	65,479	24,495
Total operating expenses	90,456	54,936	344,133	176,488
Loss from operations	(90,456)	(54,936)	(344,133)	(176,488)
Other income (expense):
Non-cash interest expense on mandatorily redeemable preferred shares	(4,378)	0	(8,333)	0
Non-cash interest expense on liability related to sale of future royalties	(7,308)	(5,633)	(19,272)	(6,134)
Change in fair value of warrant liability	0	0	0	(1,182)
Change in fair value of derivative liability	(1,717)	0	(2,980)	0
Loss from equity method investment	(1,993)	(697)	(4,308)	(2,066)
Other	8	(14)	(25)	(29)
Total other expense, net	(15,388)	(6,344)	(34,918)	(9,411)
Loss before provision for income taxes	(105,844)	(61,280)	(379,051)	(185,899)
Provision for income taxes	323	161	490	273
Net loss and comprehensive loss	$ (106,167)	$ (61,441)	$ (379,541)	$ (186,172)
Net loss per share - basic and diluted (in dollars per share)	$ (2.04)	$ (1.53)	$ (8.04)	$ (4.82)
Weighted average common shares outstanding - basic and diluted (shares)	52,077,240	40,147,735	47,210,615	38,636,072