INCOME TAXES (Tables)

12 Months Ended

Dec. 31, 2021

INCOME TAXES

Schedule of components of the entity's deferred tax assets

	December 31,
	2021		2020
Deferred tax assets
Net operating loss carryforwards	$	229,364	$	240,767
Orphan drug and research and development credits		66,616		64,252
Deferred compensation		8,819		7,760
Lease liabilities		2,564		4,399
Capitalized inventory		47		34
Deferred revenue		16,297		1,405
Other, net		1,626		1,765
Deferred tax liabilities
Operating lease right-of-use asset		(2,335)		(4,084)
Others		(607)		(537)
Total net deferred tax assets		322,391		315,761
Less: valuation allowance		(322,391)		(315,761)
Deferred tax assets, net of allowance	$	—	$	—

Schedule of reconciliation of the statutory federal income tax rate to the effective tax rate

	Year Ended December 31,
	2021		2020		2019
Federal statutory tax rate	(21.0)	%	(21.0)	%	(21.0)	%
State, Net of Federal Benefit	2.8	%	0.1	%	0.1	%
Valuation allowance	27.5	%	24.4	%	21.7	%
Stock compensation	5.6	%	4.7	%	2.8	%
Orphan drug and research and development credits	(14.0)	%	(12.7)	%	(5.1)	%
Other, net	2.7	%	4.6	%	1.5	%
Effective tax rate	3.6	%	0.1	%	0.0	%

Schedule of activity related to the entity's gross unrecognized tax benefits

The following table summarizes the activity related to our gross unrecognized tax benefits (in thousands):

	Year Ended December 31,
	2021		2020		2019
Balance at the beginning of the year	$	8,901	$	8,358	$	8,358
Increase related to current year tax positions		285		543		543
Balance at the end of the year	$	9,186	$	8,901	$	8,358