CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOW (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (21,444)	$ (13,382)
Adjustment to reconcile net loss to net cash from operating activities:
Depreciation and amortization	63	240
Stock-based compensation	7,447	4,541
Exchange rate differences		1
Realized loss on sale of short-term investment		100
Right of use asset	245
Lease liability	(173)
Changes in operating assets and liabilities:
Increase in inventory		(33)
Increase in accounts receivable		(4)
(Increase) decrease in prepaid expenses and other current assets	(41)	232
Decrease in accounts payable and accrued expenses	(2,440)	(206)
Decrease in deferred revenues		(454)
Decrease in employee related accrued expenses	(1,591)	(659)
Net cash used in operating activities	(17,934)	(9,624)
CASH FLOWS FROM INVESTING ACTIVITIES:
Short-term investments		35,901
Purchase of property and equipment	(44)	(72)
Net cash (used in) provided by investing activities	(44)	35,829
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercise of options into ordinary shares	1,532
Issuance of ordinary shares, net of issurance expenses	161,974	64,256
Net cash provided by financing activities	163,506	64,256
INCREASE IN CASH AND CASH EQUIVALENTS	145,528	90,461
CASH, CASH EQUIVALENTS AND RESTRICED CASH AT BEGINNING OF THE YEAR	101,571	36,999
CASH, CASH EQUIVALENTS AND RESTRICTED CASH AT END OF THE YEAR	247,099	127,460
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
Non-cash issuance cost	312	$ 21
Exercise of options	$ 515