Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017
Operating expenses:
Research and development	$ 4,723	$ 14,387
General and administrative	5,651	8,466
Total operating expenses	10,374	22,853
Operating loss	(10,374)	(22,853)
Other income (expense):
Interest and other income	111
Change in fair value of derivative financial instruments	(2,480)	(3,443)
Foreign exchange gain (loss)	703	(1,728)
Total other expense	(1,666)	(5,171)
Net loss	(12,040)	(28,024)
Other comprehensive (loss)
Foreign currency translation adjustments	(728)	1,775
Comprehensive loss	$ (12,768)	$ (26,249)
Net loss per share
Basic and diluted	$ (0.72)	$ (1.50)
Weighted average shares outstanding
Basic and diluted	16,671,019	18,632,740