Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue:
Collaboration revenue		$ 264		$ 295
Type of Revenue [Extensible List]	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember
Operating expenses:
Research and development	$ 6,240	$ 7,164	$ 17,228	$ 19,176
General and administrative	1,938	1,744	6,354	5,643
Buy-out of future milestones and royalties (note 10c)	6,000		6,000
Total operating expenses	14,178	8,908	29,582	24,819
Loss from operations	(14,178)	(8,644)	(29,582)	(24,524)
Other income (expense):
Interest income	325	124	558	382
Interest expense	(678)		(1,037)
Foreign exchange gain (loss)	148	778	(276)	1,503
Gain on termination of collaboration agreement (note 9c)			4,398
Net loss and comprehensive loss	(14,383)	(7,742)	(25,939)	(22,639)
Net loss attributable to preferred shareholders	(1,621)		(2,506)
Net loss attributable to common shareholders	$ (12,762)	$ (7,742)	$ (23,433)	$ (22,639)
Net loss per common share (note 5):
Basic	$ (0.63)	$ (0.43)	$ (1.34)	$ (1.26)
Diluted	$ (0.63)	$ (0.43)	$ (1.34)	$ (1.27)
Weighted-average common shares outstanding (note 5):
Basic	20,306,298	17,998,420	17,472,403	17,980,608
Diluted	20,306,298	18,009,979	17,472,403	18,000,066