CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Operating expenses:
Research and development	$ 175,977	$ 29,052	$ 216,980	$ 104,631
General and administrative	23,235	9,064	36,697	16,921
Total operating expenses	199,212	38,116	253,677	121,552
Loss from operations	(199,212)	(38,116)	(253,677)	(121,552)
Other income (expense):
Non-cash interest expense on mandatorily redeemable preferred shares	(3,955)	0	(3,955)	0
Non-cash interest expense on liability related to sale of future royalties	(5,151)	(501)	(11,964)	(501)
Change in fair value of warrant liability	0	0	0	(1,182)
Change in fair value of derivative liability	(1,263)	0	(1,263)	0
Loss from equity method investment	(1,415)	(641)	(2,315)	(1,369)
Other	(16)	14	(33)	(15)
Total other expense, net	(11,800)	(1,128)	(19,530)	(3,067)
Loss before provision for income taxes	(211,012)	(39,244)	(273,207)	(124,619)
Provision for income taxes	58	25	167	112
Net loss and comprehensive loss	$ (211,070)	$ (39,269)	$ (273,374)	$ (124,731)
Net loss per share - basic and diluted (in dollars per share)	$ (4.67)	$ (1.01)	$ (6.11)	$ (3.29)
Weighted average common shares outstanding - basic and diluted (shares)	45,226,434	38,942,545	44,736,971	37,873,755