Note 13 - Income Taxes - Components of Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Net operating loss carryforwards	$ 47,720	$ 39,822
Research and development tax credits	10,187	7,943
Capitalized research and development	21,676	14,260
Sale of future royalties	1,623	2,886
Lease liability	4,206	4,581
Accruals, reserves and other	4,827	5,004
Total deferred tax assets	90,239	74,496
Valuation allowance	(82,500)	(66,323)
Deferred tax assets net of valuation allowance	7,739	8,173
Intangible assets	(2,308)	(2,614)
Right-of-use assets	(5,216)	(5,427)
Depreciation on property and equipment	(215)	(132)
Total deferred tax liabilities	(7,739)	(8,173)
Net deferred tax assets	$ 0	$ 0