Condensed consolidated statements of cash flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Operating activities
Net loss	$ (22,082)	$ (17,612)
Non-cash items:
Change in fair value of derivative liability (Note 6)		(73)
Stock-based compensation (Note 5(c))	1,685	915
Unrealized foreign exchange loss and others	271	48
Changes in operating assets and liabilities:
Receivable, prepayments and deposits	(484)	(771)
Accounts payable and other liabilities	(973)	3,705
Cash used in operating activities	(21,583)	(13,788)
Investing activities
Purchase of investments		(34,557)
Proceeds from maturity of investments	16,500	31,575
Purchase of property and equipment	(452)	(320)
Cash provided by (used in) investing activities	16,048	(3,302)
Financing activities
Proceeds from exercise of stock options	377	4
Payment on capital lease obligations	(7)	(1)
Cash provided by financing activities	370	3
Effect of exchange rate changes on cash and cash equivalents	11	31
Net change in cash and cash equivalents during the period	(5,154)	(17,056)
Cash and cash equivalents, beginning of period	32,301	39,526
Cash and cash equivalents, end of period	27,147	22,470
Supplemental disclosure of cash flow information:
Interest received	484	$ 249
Non-cash investing and financing activities:
Accrued purchase of property & equipment	$ (77)