INCOME TAXES (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Schedule of Effective Income Tax Reconciliation

The differences between the effective income tax rate and the statutory tax rates during the years ended 2018, 2017 and 2016 are as follows (in thousands):

	Year Ended December 31,
	2018			2017			2016
Net loss before tax	$	(98,418	)	$	(70,430	)	$	(83,118	)
Statutory combined U.S. federal and state tax rate	21.00		%	34.00		%	34.00		%
Statutory federal and state taxes	(20,668		)	(23,946		)	(28,260		)
Increase (decrease) in taxes recoverable resulting from:
Effect of change in valuation allowance	25,959			(4,154		)	28,446
Non-deductible share-based compensation	884			695			1,247
Tax deductions for share-based compensation	(2,924		)	(80		)	(12		)
Tax credits	(5,130		)	(2,563		)	(2,906		)
Share issue costs - temporary difference	—			—			(78		)
Write off of Methylgene US Inc. net operating loss	—			307			—
Differential in income tax rates of foreign subsidiary	(1		)	(169		)	261
Change in tax rate	—			303			—
Tax Cuts and Jobs Act	—			28,569			—
Uncertain tax positions	1,283			646			3,921
Return to provision and other true-ups	375			394			(2,619		)
Other differences	222			(2		)	—
Income tax benefit	$	—		$	—		$	—

Schedule of deferred tax

The following table summarizes the significant components of our deferred tax assets (in thousands):

	December 31,
	2018			2017
Deferred tax assets:
Tangible and intangible depreciable assets	$	8,123		$	17,927
Stock compensation	6,515			4,976
Provisions	1,020			611
Net operating loss carry forwards	74,721			44,598
Capital loss carryforward	178			83
Canada scientific research and experimental development expenditures	5,467			5,467
U.S. research and development tax credits	10,613			7,016
Total gross deferred tax assets	106,637			80,678
Less valuation allowance	(106,637		)	(80,678		)
Net deferred tax assets	$	—		$	—

Schedule of expiration of NOLs

The NOLs expire as follows (in thousands):

	US				Canada
	Federal		State		Federal		Provincial
Expires in:
2030	$	—	$	—	$	5,907	$	5,985
2031	—		—		7,059		7,066
2032	—		—		13,308		12,433
2033	2,225		2,232		18,623		19,385
2034	7,276		22,162		32,401		31,809
2035	53,359		52,950		1,084		1,084
2036	23,379		—		777		777
2037	65,509		—		697		697
2038	—		—		7		$	7
Does not expire	102,863		—		—		$	—
	$	254,611	$	77,344	$	79,863	$	79,243

Schedule of reconciliation of the beginning and ending gross amounts of unrecognized tax positions

A reconciliation of the beginning and ending amounts of unrecognized tax positions are as follows (in thousands):

	Federal								Provincial/State
	December 31,								December 31,
	2018		2017			2016			2018		2017			2016
Unrecognized tax positions, beginning of year	$	1,693	$	1,095		$	509		$	7,556	$	7,333		$	2,274
Gross increase — current period tax positions	924		588			598			454		227			195
Gross decrease — prior period tax positions	—		—			(9		)	—		(3		)	—
Gross increase — prior period tax positions	—		11			—			—		—			4,866
Expiration of statute of limitations	—		(1		)	(3		)	—		(1		)	(2		)
Unrecognized tax positions, end of year	$	2,617	$	1,693		$	1,095		$	8,010	$	7,556		$	7,333