Note 8 - Share-based Compensation (Tables)

9 Months Ended

Sep. 30, 2023

Notes Tables

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

	Three months ended				Nine months ended
	September 30,				September 30,
	2023		2022		2023		2022
Research and development	$	118	$	132	$	391	$	389
Selling, general and administrative		133		148		455		514
Total share-based compensation	$	251	$	280	$	846	$	903

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, 2022		2,182,708		$	4.04		7.5	$	343
Stock options granted		543,513			1.69
Stock options exercised		(199	)		1.49
Stock options forfeited		(275,662	)		2.15
Stock options expired		(6,349	)		16.09
Balance, September 30, 2023		2,444,011		$	3.70		6.7	$	—
Exercisable, September 30, 2023		1,558,484		$	4.61		5.5	$	—

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

				Weighted
				average
				grant date
	Number of			fair value
	shares			per share
Balance, December 31, 2022		21,526		$	4.33
RSUs granted		331,552			1.70
RSUs released		(241,197	)		1.93
RSUs forfeited		(111,881	)		1.70
Balance, September 30, 2023		—		$	n/a