Note 13 - Income Taxes (Tables)

12 Months Ended

Dec. 31, 2014

Income Tax Disclosure [Abstract]

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

	Years Ended December 31,
	2014			2013			2012
Income tax benefit using U.S. federal statutory rate	$	(1,136	)	$	(2,690	)	$	(2,710	)
Permanent differences		124			299			38
Orphan drug credit permanent addback		674			-			-
State income taxes, net of federal benefit		(303	)		(389	)		(368	)
Tax credits		(2,176	)		(7,164	)		(95	)
Expiring net operating losses and tax credits		312			2,566			287
Change in valuation allowance		4,394			7,286			2,988
Mark to market derivative liability		(1,779	)		-			-
Other		(110	)		92			(140	)
	$	-		$	-		$	-

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

	Years Ended December 31,
	2014			2013			2012
Net operating loss carryforwards	$	29,217		$	26,304		$	26,560
Federal and state tax credits		12,126			9,941			2,777
Deferred revenue		-			1,147			1,139
Accrued expenses		478			332			155
Patents		531			612			692
Other		100			300			27
		42,452			38,636			31,350
Valuation allowance		(42,452	)		(38,636	)		(31,350	)
Net deferred tax asset	$	-		$	-		$	-