CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (unaudited) - USD ($) shares in Thousands, $ 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	$ 7,944	$ 2,779	$ 12,630	$ 6,034
General and administrative	2,617	2,351	5,672	4,303
Loss from change in fair value of contingent consideration	44,000	3,900	43,000	2,700
Total operating expenses	54,561	9,030	61,302	13,037
Loss from operations	(54,561)	(9,030)	(61,302)	(13,037)
Other income:
Other income, net	226	72	487	116
Total other income, net	226	72	487	116
Net loss and comprehensive loss	$ (54,335)	$ (8,958)	$ (60,815)	$ (12,921)
Net loss per share — basic and diluted (in dollars per share)	$ (0.67)	$ (0.16)	$ (0.77)	$ (0.28)
Weighted-average number of common shares used in net loss per share- basic and diluted (in shares)	80,739	56,421	79,107	46,105