Note 10 - Income Taxes (Tables)

12 Months Ended

Dec. 31, 2022

Notes Tables

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

	December 31,
	2022		2021
Current
Federal	$	—	$	—
State		—		—
		—		—
Deferred
Federal	$	—	$	—
State		—		—
Total deferred tax expense		—		—
Total income tax expense	$	—	$	—

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

	December 31,
	2022			2021
Federal tax benefit at statutory rate		21	%		21	%
Change in valuation allowance		6.5	%		(21	)%
Section 382 limitation		(24.1	)%		—
Other non-deductible expenses		—			(1	)%
Stock based compensation		—			—
Other		(3.4	)%		1	%
Total		—			—

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

	December 31,
	2022			2021
Net operating loss carry forwards	$	504		$	18,205
Research and development tax credits		232			404
Capitalized research and development		13,026			—
Stock based compensation and other		3,878			3,694
Operating lease obligation		856			1,339
Total deferred tax assets		18,496			23,642
Less: Valuation allowance		(18,189	)		(23,179	)
Deferred tax liabilities		—			—
Operating lease right-of-use assets		(307	)		(463	)
Net deferred tax assets	$	—		$	—

Summary of Income Tax Contingencies [Table Text Block]

	Amount
Balance at January 1, 2021	$	164
Gross increase/ (decrease) related to prior year tax positions		—
Gross increase related to current year positions		—
Reductions to unrecognized tax benefits related to lapsing statute of limitations		—
Balance at December 31, 2021	$	164
Gross increase/ (decrease) related to prior year tax positions		—
Gross increase related to current year positions		1
Reductions to unrecognized tax benefits related to lapsing statute of limitations		—
Balance at December 31, 2022	$	165