INCOME TAXES (Tables)

12 Months Ended

Dec. 31, 2017

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 2017, 2016 and 2015 are as follows (in thousands):

	Year Ended December 31,
	2017			2016			2015
Net loss before tax	$	(70,430	)	$	(83,118	)	$	(64,544	)
Statutory combined U.S. federal and state tax rate	34.00		%	34.00		%	34.00		%
Statutory federal and state taxes	(23,946		)	(28,260		)	(21,945		)
Increase (decrease) in taxes recoverable resulting from:
Effect of change in valuation allowance	(4,154		)	28,446			22,350
Non-deductible share-based compensation	695			1,247			923
Tax credits	(2,563		)	(2,906		)	(2,430		)
Share issue costs - temporary difference	—			(78		)	(184		)
Write off of Methylgene US NOL	307			—			—
Differential in income tax rates of foreign subsidiary	(169		)	261			31
Change in tax rate	303			—			—
Tax Cuts and Jobs Act	28,569			—			—
Uncertain tax positions	646			3,921			1,961
Return to provision and other true-ups	368			(2,619		)	(899		)
Other differences	(56		)	(12		)	193
Income tax benefit	$	—		$	—		$	—

Schedule of deferred tax

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

	December 31,
	2017			2016
Deferred tax assets:
Tangible and intangible depreciable assets	$	17,927		$	990
Stock compensation	4,976			6,635
Provisions	611			853
Net operating loss carry forwards	44,598			66,489
Capital loss carryforward	83			51
Scientific research and experimental development expenditures	5,467			5,531
Research and development tax credits	7,016			4,266
Total gross deferred tax assets	80,678			84,815
Less valuation allowance	(80,678		)	(84,815		)
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	24,044		—		1,408		1,408
	$	110,283	$	77,344	$	80,567	$	79,947

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,
	2017			2016			2015			2017			2016			2015
Unrecognized tax positions, beginning of year	$	1,095		$	509		$	42		$	7,333		$	2,274		$	18
Gross increase — current period tax positions	588			598			445			227			195			259
Gross decrease — prior period tax positions	—			(9		)	(4		)	(3		)	—			(3		)
Gross increase — prior period tax positions	11			—			26			—			4,866			2,000
Expiration of statute of limitations	(1		)	(3		)	—			(1		)	(2		)	—
Unrecognized tax positions, end of year	$	1,693		$	1,095		$	509		$	7,556		$	7,333		$	2,274