Note 9 - Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Notes Tables

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

(in thousands)	2023			2022
Deferred tax assets:
Net operating loss carryforwards	$	316,962		$	303,729
Research and development credit		45,806			42,031
Noncash compensation		12,275			10,325
Disallowed interest		3,328			3,882
Capitalized R&D Expenses		36,613			39,411
Other		3,333			985
Deferred tax asset, excluding valuation allowance		418,317			400,363
Less valuation allowance		(418,317	)		(400,363	)
Net deferred tax assets	$	—		$	—

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

	For the year ended December 31,
(in thousands)	2023			2022			2021
Loss before income taxes, as reported in the consolidated statements of operations	$	13,062		$	(198,335	)	$	(348,101	)
Computed “expected” tax benefit	$	2,743		$	(41,650	)	$	(73,101	)
Increase (decrease) in income taxes resulting from:
Expected benefit from state and local taxes		111			(7,242	)		(3,445	)
Research and development credits		(3,430	)		(6,389	)		(8,337	)
Officer Compensation Limitation		1,167			4,391			439
Other		(179	)		374			428
Stock options		(12,445	)		17,599			(6,726	)
Change in state tax rates		(5,531	)		-			-
Change in the balance of the valuation allowance for deferred tax assets		17,954			32,917			90,742
	$	390		$	—		$	—