Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Condensed Consolidated Statements of Operations
License and collaboration revenue - related party	$ 4,141	$ 6,117	$ (2,488)	$ 28,572
Operating expenses:
Research and development	17,293	12,145	49,092	45,249
General and administrative	4,015	3,361	11,642	10,180
Total operating expenses	21,308	15,506	60,734	55,429
Loss from operations	(17,167)	(9,389)	(63,222)	(26,857)
Interest income and other, net	656	654	1,989	1,798
Loss before income tax benefit	(16,511)	(8,735)	(61,233)	(25,059)
Income tax benefit	102	0	1,547	0
Net loss	$ (16,409)	$ (8,735)	$ (59,686)	$ (25,059)
Net loss per share, basic and diluted	$ (0.61)	$ (0.38)	$ (2.36)	$ (1.15)
Weighted-average shares used to compute net loss per share, basic and diluted	26,956,957	22,912,279	25,315,512	21,750,562