Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities
Net loss	$ (20,217)	$ (13,342)
Adjustments to reconcile net loss to net cash used in operating activities:
Non-cash other expense, net	(27)	(112)
Non-cash interest income	(13)	(10)
Non-cash interest expense	227
Depreciation and amortization expense	125	133
Amortization of right-of-use assets	109
Stock-based compensation	1,907	1,244
Other, net	(8)	(6)
Changes in operating assets and liabilities:
Changes in long-term receivables	(10)	(3)
Changes in other receivables and prepaid expenses	(2,650)	(1,992)
Changes in accounts payable	4,302	(1,413)
Changes in accrued expenses and other liabilities	(4,374)	(1,311)
Changes in other non-current liabilities	(30)	22
Changes in income tax liabilities	18	451
Net cash used in operating activities	(20,625)	(16,339)
Cash flows from investing activities
Purchases of plant and equipment and intangible assets	(42)	(160)
Net cash provided (used in) by investing activities	(42)	(160)
Cash flows from financing activities
Proceeds from sale of ordinary shares	9,978	19,388
Proceeds from long-term debt		189
Equity transaction costs	(299)	(518)
Net cash provided by (used in) financing activities	9,679	19,059
Effects of foreign currency translation on cash and cash equivalents	27	112
Net (decrease) increase in cash and cash equivalents	(10,961)	2,672
Cash and cash equivalents at beginning of period	102,003	86,769
Cash and cash equivalents at end of period	91,042	89,441
Supplemental disclosures of cash flow information:
Interest paid	483
Equity transaction costs incurred in prior periods and paid in current period	49	28
Equity transaction costs included in accounts payable and accrued expenses	$ 20	$ 426