Note 9 - Summary of Stock Options (Tables)

12 Months Ended

Dec. 31, 2015

Notes Tables

Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]

	Year Ended December 31, 2015									Year Ended December 31, 2014
						Weighted									Weighted
				Weighted		Average		Aggregate					Weighted		Average		Aggregate
	Number			Average		Remaining		Intrinsic		Number			Average		Remaining		Intrinsic
	of			Exercise		Contractual		Value		of			Exercise		Contractual		Value
	Shares			Price		Term (years)		(in thousands)		Shares			Price		Term (years)		(in thousands)
Options outstanding, beginning of period		2,291,783		$	1.02		9.32	$	-		363,413		$	1.24		8.80
Options granted		6,031,004		$	0.73						1,901,476		$	0.60
Options assumed from PLC		-		$	-						68,238		$	10.24
Options exercised		-		$	-						(160	)	$	0.12
Options canceled		(145,496	)	$	0.69						(41,184	)	$	1.83
Options outstanding, end of period		8,177,291		$	0.81		9.37	$	1,194,180		2,291,783		$	1.02		9.32	$	-
Vested and exercisable and expected to vest, end of period		7,418,006		$	0.82		9.33	$	1,094,069		2,099,687		$	1.06		9.29	$	-
Vested and exercisable, end of period		974,849		$	1.58		7.20	$	143,458		519,901		$	2.45		7.89	$	-

Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block]

			Options Outstanding						Options Exercisable
							Weighted
			Number		Weighted		Average		Number		Weighted
			Outstanding		Average		Remaining		Exercisable		Average
Range of			as of		Exercise		Contractual		as of		Exercise
Exercise Prices			December 31, 2015		Price		Term (Years)		December 31, 2015		Price
	$0.33			100,000	$	0.33		9.37		-	$	-
$0.46	-	$0.47		635,000	$	0.47		9.11		-	$	-
	$0.60			1,768,980	$	0.60		8.55		585,542	$	0.60
	$0.75			4,949,004	$	0.75		9.97		-	$	-
$0.89	-	$0.99		335,000	$	0.96		9.60		-	$	-
	$1.24			312,373	$	1.24		6.79		312,373	$	1.24
$7.00	-	$9.00		57,603	$	8.64		1.61		57,603	$	8.64
$12.00	-	$18.63		19,081	$	15.29		1.75		19,081	$	15.29
	$37.00			250	$	37.00		1.73		250	$	37.00
				8,177,291	$	0.81		9.37		974,849	$	1.58

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	Year Ended December 31,
	2015		2014
Expected term (in years)		5%		5%
Average volatility		63%		61%
Risk-free interest rate		1.70%		1.80%
Dividend yield		0%		0%

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]

	Year Ended December 31,
	2015		2014
Research and development	$	18	$	5
Selling, general and administrative		202		179
Total	$	220	$	184