Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (39,052)	$ (31,416)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	5,102	4,498
Depreciation	85	228
Other	(167)	30
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(1,831)	(483)
Accrued liabilities	1,092	681
Accounts payable	(371)	(2,093)
Net cash used in operating activities	(35,142)	(28,555)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property and equipment	(59)	(92)
Net cash used in investing activities	(59)	(92)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock upon follow-on offering, net of offering costs	45,996	27,422
Proceeds from issuance of term loan, net of issuance costs	4,955
Proceeds from exercise of common stock options	178	23
Net cash provided by financing activities	51,129	27,445
Effect of foreign exchange rate changes on cash, cash equivalents and restricted cash	(36)	6
NET INCREASE / (DECREASE) IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	15,892	(1,196)
CASH, CASH EQUIVALENTS AND RESTRICTED CASH - Beginning of period	100,536	109,207
CASH, CASH EQUIVALENTS AND RESTRICTED CASH - End of period	116,428	108,011
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid for income taxes, net	15	221
Cash paid for interest	9
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING INFORMATION:
Property and equipment purchases included in accrued liabilities		$ 5
Issuance of common stock warrant	$ 116