Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Revenue:
Collaboration revenue (note 12)		$ 311
Type of Revenue [Extensible List]	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember
Operating expenses:
Research and development	$ 23,634	$ 25,573
General and administrative	8,382	7,313
Buy-out of future milestones and royalties (note 13d)	6,000
Total operating expenses	38,016	32,886
Loss from operations	(38,016)	(32,575)
Other income (expense):
Interest income	1,216	477
Interest expense	(1,394)
Foreign exchange gain (loss)	(701)	1,394
Gain on termination of collaboration agreement (note 12a)	4,398
Net loss and comprehensive loss	(34,497)	(30,704)
Net loss attributable to preferred shareholders	(2,881)
Net loss attributable to common shareholders	$ (31,616)	$ (30,704)
Net loss per common share (note 6):
Basic	$ (1.63)	$ (1.71)
Diluted	$ (1.63)	$ (1.72)
Weighted-average common shares outstanding (note 6):
Basic	19,425,711	17,985,061
Diluted	19,425,711	18,001,759