Note 8 - Stock Based Awards (Tables)

9 Months Ended

Sep. 30, 2022

Notes Tables

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

						Weighted
						Average
				Weighted		Remaining		Aggregate
				Average		Contractual		Intrinsic
	Number of			Exercise		Life		Value
	Shares			Price		(in years)		(in thousands)
Balances, January 1, 2022		2,439,253		$	3.96
Options granted		2,813,641			1.63
Options cancelled		(643,879	)		3.56
Options exercised		—			—
Balances, September 30, 2022		4,609,015		$	2.60		7.2	$	358
Outstanding and expected to vest as of September 30, 2022		4,238,168		$	2.63		7.1	$	358
Exercisable as of September 30, 2022		2,126,154		$	3.09		4.6	$	358

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

	September 30,			September 30,
	2022			2021
Expected volatility		113.0	%		114.4	%
Risk-free interest rate		2.1	%		0.7	%
Dividend yield		0.0	%		0.0	%
Expected life (in years)		6.0			5.9