Note 11 - Equity Incentive Plans (Tables)

9 Months Ended

Sep. 30, 2020

Notes Tables

Share-based Payment Arrangement, Option, Activity [Table Text Block]

							Weighted
	Shares			Number of			Average
	Available			Options			Exercise
	For Grant			Outstanding			Price
Balance at January 1, 2020		295,180			1,811,652		$	2.74
2019 Plan Amendment		6,400,000			—		$	—
PRSUs granted, net of tax forfeitures		(278,535	)		—		$	—
Granted		(4,957,800	)		4,957,800		$	2.10
Exercised		—			(305,179	)	$	1.32
Forfeited		85,910			(85,992	)	$	0.39
Canceled		9,573			(57,751	)	$	10.57
Balance at September 30, 2020		1,554,328			6,320,530		$	2.27

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

	Nine Months Ended September 30,
	2020			2019
Risk-free interest rate		0.40% - 0.88%			1.89% - 2.31%
Expected term	5.22 - 10.00 Years			5.39 - 6.08 Years
Expected volatility		94% - 108%			83% - 85%
Dividend yield		—	%		—	%

Share-based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]

	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2019		2020		2019
	(in thousands)				(in thousands)
Research and development	$	268	$	63	$	1,405	$	222
General and administrative		647		83		2,466		268
Total stock-based compensation	$	915	$	146	$	3,871	$	490