Note 12 - Share-based Compensation (Tables)

6 Months Ended

Jun. 30, 2021

Notes Tables

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

	Three Months Ended June 30				Six Months Ended June 30
	2021		2020		2021		2020
Research and development	$	140	$	131	$	271	$	238
General and administrative		306		305		686		591
Total share-based compensation	$	446	$	436	$	957	$	829

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

	Shares Underlying Options Outstanding			Weighted Average Exercise Price Per Share		Aggregate Intrinsic Value
Balances at December 31, 2020		1,389,568		$	5.38	$	7,109
Granted		85,000			9.69
Exercised		(40,000	)		6.11		132
Expired/cancelled		(13,476	)		6.54
Balances at June 30, 2021		1,421,092		$	5.63	$	-

Share-based Payment Arrangement, Option, Exercise Price Range [Table Text Block]

			Outstanding, Vested and Expected to Vest						Options Vested and Exercisable
Per Share Exercise Price			Shares		Weighted Average Remaining Contractual Life (Years)		Weighted Average Exercise Price		Options Exercisable		Weighted Average Remaining Contractual Life (Years)
$2.00	-	$2.99		120,500		4.5	$	2.44		120,500		4.5
$3.00	-	$3.99		2,500		5.8		3.06		2,500		5.8
$4.00	-	$4.99		953,567		7.9		4.51		792,526		7.7
$5.00	-	$9.99		274,525		7.1		8.10		216,088		6.5
$10.00	-	$27.06		70,000		3.7		16.80		51,667		1.6
				1,421,092		7.2	$	5.63		1,183,281		6.9