Consolidated statements of operations and comprehensive loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue (Note 9)		$ 25,000
Operating expenses
Research and development (Note 10)	$ 4,417	41,789	$ 36,267
Acquired in-process research and development (Note 3)	47,716
General and administrative (Note 10)	18,826	15,835	14,852
Total operating expenses	70,959	57,624	51,119
Loss from operations	(70,959)	(32,624)	(51,119)
Other income, net
Interest expense	(1)	(4)	(4)
Other income, net (Note 11)	1,518	1,043	940
Total Other income (expenses)	1,517	1,039	936
Net loss	$ (69,442)	$ (31,585)	$ (50,183)
Net loss per common stock—basic and diluted (Note 12)	$ (2.57)	$ (1.34)	$ (2.14)
Basic and diluted weighted average number of common stock outstanding (Note 12)	27,030,355	23,519,508	23,450,315
Comprehensive loss:
Net loss	$ (69,442)	$ (31,585)	$ (50,183)
Other comprehensive income—unrealized gain on available-for-sale securities		70	99
Comprehensive loss	$ (69,442)	$ (31,515)	$ (50,084)