Note 9 - Equity Plans and Related Equity Activities (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2023

Dec. 31, 2022

Notes Tables

Share-Based Payment Arrangement, Cost by Plan [Table Text Block]

	Three Months Ended March 31,
	2023		2022
Research and development	$	97	$	119
General and administrative		390		302
Total stock-based compensation	$	487	$	421

	Year Ended December 31,
	2022		2021
Research and development	$	583	$	292
General and administrative		1,300		851
Total stock-based compensation	$	1,883	$	1,143

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

	Year Ended December 31,
	2022			2021
Option Grants:
Expected term (years)	5.00	-	6.06	5.62	-	10.00
Expected volatility	71%	-	86%		88%
Risk-free interest rate	0.53%	-	4.07%	0.60%	-	1.20%
Expected dividend		0%			0%
ESPP:
Expected term (years)	0.50	-	2.00
Expected volatility	83%	-	93%
Risk-free interest rate	4.37%	-	4.60%
Expected dividend		0%

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

	Awards Available to Grant			Number of Awards Outstanding			Weighted Average Exercise Price		Weighted Average Remaining Contractual Terms (Years)		Aggregate Intrinsic Value
Outstanding at December 31, 2021		888,435			3,536,715		$	2.71
Shares authorized added to 2022 Plan		2,573,405
Shares not returned to plan		(913,842	)
Options Granted		(2,097,010	)		2,097,010		$	3.18
Options Exercised		-			(75,550	)	$	1.45
Options Cancelled		839,156			(839,156	)	$	2.43
Restricted stock awards granted		(23,518	)		23,518		$	-
Restricted stock awards vested		-			(23,518	)	$	-
Restricted stock units granted		(243,618	)		243,618		$	-
Restricted stock units vested		-			(80,668	)	$	-
Restricted stock units forfeited		42,415			(42,415	)	$	-
Outstanding at December 31, 2022		1,065,423			4,839,554		$	2.91		6.66	$	82
Vested and exercisable at December 31, 2022					2,685,009		$	2.75		4.41	$	-
Vested and expected to vest at December 31, 2022					4,824,187		$	2.91		6.65	$	82

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

			Awards Outstanding						Awards Exercisable
Range of Exercise Price			Number of Awards		Weighted-Average Remaining Contractual Term (Years)		Weighted Average Exercise Price per Share		Number of Awards		Weighted-Average Remaining Contractual Term (Years)		Weighted Average Exercise Price per Share
$1.27	to	$2.65		3,103,997		6.12	$	2.08		1,692,935		3.09	$	1.68
$3.03	to	$4.79		1,384,481		7.55	$	4.38		820,036		6.72	$	4.13
$6.54	to	$7.62		230,541		6.83	$	6.84		172,038		6.40	$	6.69
				4,719,019		6.58	$	2.99		2,685,009		4.41	$	2.75