Condensed consolidated statements of cash flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Operating activities
Net loss	$ (6,711)	$ (6,412)
Non-cash items and reclassifications:
Change in fair value of derivative liabilities	(50)	7
Stock-based compensation	433	266
Foreign exchange loss and others	31	468
Changes in operating assets and liabilities:
Receivable, prepayments and deposits	(465)	(398)
Accounts payable and other liabilities	890	(231)
Cash used in operating activities	(5,872)	(6,300)
Investing activities
Purchase of investments	(13,002)
Proceeds from maturity of investments	15,025	6,066
Purchase of property and equipment	(27)	(6)
Cash provided by investing activities	1,996	6,060
Financing activities
Proceeds from exercise of stock options		72
Cash provided by financing activities		72
Effect of exchange rate changes on cash and cash equivalents	41	(455)
Net change in cash and cash equivalents during the period	(3,835)	(623)
Cash and cash equivalents, beginning of period	39,526	14,906
Cash and cash equivalents, end of period	35,691	14,283
Supplemental disclosure of cash flow information:
Interest received	$ 121	$ 15