CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Operating activities
Net loss	$ (14,399)	$ (12,600)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	364	645
Stock-based compensation expense	649	617
Non-cash interest expense	108	188
Change in fair value of redeemable convertible preferred stock warrant	12
Changes in operating assets and liabilities:
Accounts receivable	(1,137)	153
Prepaid expenses and other assets	(537)	(230)
Restricted cash and other deposits	(1,351)	301
Account payable	(338)	926
Deferred revenue	933	773
Contingently repayable grant funding received	(204)	(310)
accrued expenses and other liabilities	127	326
Net cash used in operating activities	(15,773)	(9,211)
Investing activities
Maturities of short term government obligations	3,516
purchase of property and equipment	(202)	(553)
Net cash provided by (used in ) investing activities	3,314	(553)
Financing activities
Vesting of restricted stock	10	10
Principle payments on loan payable		(916)
Deferred IPO costs paid	(2,650)
Issuance of convertible note		7,092
Proceeds from Initial Public Offering	65,100
Exercise of stock options	48	49
Net cash provided by financing activities	62,508	6,235
Effect of exchange rate changes on cash	262	91
Net (decrease) increase in cash and cash equivalents	50,311	(3,438)
Cash and cash equivalents at beginning of period	32,337	16,592
Cash and cash equivalents at end of period	82,648	13,154
Cash paid during the year for:
Interest	486	291
Supplemental Noncash Financing Activities:
Reclassification of IPO costs from non-current assets to additional paid-in capital	4,324
Initial public offering costs in accounts payable and accrued liabilities	1,372
Accrued dividends and accretion of preferred stock to redemption value	$ 4,566	$ 3,123