Note 11 - Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Notes Tables

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

	Year Ended December 31,
	2023			2022
Domestic	$	(42,210	)	$	(58,505	)
Foreign		—			—
	$	(42,210	)	$	(58,505	)

Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]

	December 31,
	2023		2022
Current
Federal	$	—	$	—
State		—		3
Foreign		—		—
Total current		—		3
Deferred
Federal		—		—
State		—		—
Foreign		—		—
Total deferred		—		—
Total provision for income taxes	$	—	$	3

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

	Year Ended December 31,
	2023			2022
Federal tax at statutory rate		21.0	%		21.0	%
State tax at statutory rate		—			8.4
Research and development credits		3.7			0.9
Return to provision		2.6			—
Change in valuation allowance		(19.1	)		(18.4	)
Deferred adjustment		(1.6	)		(5.3	)
Change in tax rate		(5.8	)		—
Uncertain tax position		—			(5.7	)
Other		(0.8	)		(0.9	)
Provision for income taxes		—	%		—	%

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

	December 31,
	2023			2022
Deferred tax assets
Accruals	$	1,502		$	3,404
Net operating loss carryforwards		61,072			56,447
Tax credit carryforwards		9,815			7,111
Stock-based compensation		7,704			8,784
R&D capitalization		7,384			3,810
Lease liability		1,920			2,948
Fixed assets		7			—
Intangibles		99			—
Gross deferred tax assets		89,503			82,504
Valuation allowance		(87,853	)		(79,779	)
Total deferred tax assets		1,650			2,725
Deferred tax liabilities
Intangibles		—			(117	)
Right-of-use asset		(1,650	)		(2,593	)
Fixed assets		—			(15	)
Total deferred tax liabilities		(1,650	)		(2,725	)
Net deferred tax assets/(liabilities)	$	—		$	—

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

	December 31,
	2023			2022
Unrecognized tax benefits at beginning of year	$	8,925		$	5,140
Increases related to current year tax positions		1,575			2,055
Increases related to prior year tax positions		1,129			1,730
Decreases related to prior year tax positions		(1,459	)		—
Unrecognized tax benefits at end of year	$	10,170		$	8,925