Note 8 - Share-based Compensation (Tables)

6 Months Ended

Jun. 30, 2022

Notes Tables

Schedule of Share-based Compensation, Expense [Table Text Block]

	Three months ended				Six months ended
	June 30,				June 30,
	2022		2021		2022		2021
Research and development	$	130	$	211	$	257	$	417
Selling, general and administrative		174		173		366		383
Total share-based compensation	$	304	$	384	$	623	$	800

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

	Options outstanding
	Number of shares			Weighted average exercise price		Weighted average remaining contractual term (years)		Aggregate intrinsic value (in thousands)
Balance, December 31, 2021		1,649,686		$	5.00		7.6	$	—
Stock options granted		504,949			1.53
Stock options exercised		—
Stock options forfeited		(90,688	)		3.68
Stock options expired		(3,111	)		9.55
Balance, June 30, 2022		2,060,836		$	4.20		7.9	$	—
Exercisable, June 30, 2022		955,545		$	5.99		6.5	$	—

Schedule of Nonvested Restricted Stock Units Activity [Table Text Block]

				Weighted
				average
				grant date
	Number of			fair value
	shares			per share
Balance, December 31, 2021		200,271		$	4.13
RSUs granted		269,204			1.49
RSUs released		(311,929	)		2.74
RSUs forfeited		(87,718	)		1.49
Balance, June 30, 2022		69,828		$	3.44