Note 11 - Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

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

	Year Ended December 31,
	201 9			201 8
Tax at federal statutory rate	$	(4,084	)	$	(5,787	)
State taxes, net of federal benefit		(1,022	)		(1,023	)
Permanent differences		97			228
Change in valuation allowance		5,205			6,582
Research credits		(192	)		—
Other		(4	)		—
Provision for taxes	$	—		$	—

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

	As of December 31,
	201 9			201 8
Deferred tax assets:
Federal, state and foreign net operating losses	$	75,863		$	70,286
Research and other credits		4,361			3,655
Operating lease liability		1,237			—
Accruals and other		2,847			4,317
Total deferred tax assets		84,308			78,258
Less: Valuation allowance		(82,755	)		(78,082	)
Total net deferred tax assets		1,553			176
Deferred liabilities:
Fixed assets		(198	)		(176	)
Operating lease right of use asset		(1,355	)		—
Total deferred tax liabilities		(1,553	)		(176	)
Net deferred tax assets (liabilities)	$	—		$	—

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

	As of December 31,
	201 9		201 8
Balance at beginning of year	$	1,760	$	1,747
Increase based on the tax positions in the current year		177		29
Decrease for tax positions of prior year		157		(16	)
Balance at end of year	$	2,094	$	1,760