Condensed consolidated statements of cash flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Operating activities
Net loss	$ (25,758)	$ (16,197)
Non-cash items and reclassifications:
Change in fair value of derivative liabilities	(81)	70
Stock-based compensation	1,405	1,145
Foreign exchange loss and others	122	505
Changes in operating assets and liabilities:
Receivable, prepayments and deposits	(357)	(318)
Accounts payable and other liabilities	3,440	(1,515)
Cash used in operating activities	(21,229)	(16,310)
Investing activities
Purchase of investments	(56,336)
Proceeds from maturity of investments	53,598	18,163
Purchase of property and equipment	(616)	(16)
Cash (used in) provided by investing activities	(3,354)	18,147
Financing activities
Public offering of common stock	75,368	98,038
Public offering costs	(4,531)	(6,063)
Proceeds from exercise of stock options	440	1,121
Payment on capital lease obligation	(2)
Cash provided by financing activities	71,275	93,096
Effect of exchange rate changes on cash and cash equivalents	7	(466)
Net change in cash and cash equivalents during the period	46,699	94,467
Cash and cash equivalents, beginning of period	39,526	14,906
Cash and cash equivalents, end of period	86,225	109,373
Supplemental disclosure of cash flow information:
Interest received	391	36
Non-cash investing and financing activities:
Assets acquired through capital leases	35
Accrued purchase of property & equipment	103
Accrued offering costs	306	$ 169
Exercise of warrants on a net settlement basis	$ (43)