Note 9 - Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Notes Tables

Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block]

	2020
Domestic	$	(176,613	)
Foreign		(6,201	)
Loss before provision for income taxes	$	(182,814	)

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

	2020			2019			2018
Income tax benefit at federal statutory rate (21% for 2020, 2019 and 2018)	$	(38,391	)	$	(22,868	)	$	(21,263	)
State and local income taxes net of federal tax benefit		(2,544	)		(1,591	)		(2,547	)
Permanent items		774			691			503
Rate change		(82	)		625			(29	)
Expiration of attribute carryforwards		3,774			3,976			2,183
Research and development tax credits		(4,080	)		(4,938	)		(4,905	)
Foreign rate differential		542			-			-
Other		1,456			281			18
Change in valuation allowance		38,551			23,824			26,040
Income tax expense	$	-		$	-		$	-

Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]

	2020		2019
Balance at January 1,	$	7,210	$	5,976
Additions to current period tax positions		1,020		1,234
Additions to prior period tax positions		−		−
Reductions to prior period tax provisions		−		−
Balance at December 31,	$	8,230	$	7,210

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

	2020			2019
Deferred tax assets:
Net federal and state operating losses	$	159,939		$	155,190
Research and development credits		66,331			63,275
Royalty income		28,034			-
Stock-based compensation		10,732			9,786
Leasing obligations		1,135			1,070
Other		5,563			3,801
Total deferred tax assets		271,734			233,122
Deferred tax liabilities:
Fixed assets		(124	)		(114	)
Right of use asset		(854	)		(803	)
Total deferred tax liabilities		(978	)		(917	)
Valuation allowance		(270,756	)		(232,205	)
Net deferred tax assets	$	−		$	−