Note 6 - Stock-based Compensation (Tables)

3 Months Ended

Mar. 31, 2020

Notes Tables

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

	Three Months Ended March 31,
	2020		2019
Research and development	$	96,530	$	13,596
General and administrative		94,850		77,608
Total stock-based compensation expense	$	191,380	$	91,204

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

	Number of Options			Weighted average exercise price per share		Weighted average remaining contractual life (in years)		Aggregate intrinsic value
Balance at January 1, 2020		309,276		$	55.78			$	—
Granted		873,500			0.47
Expired		(147	)		142.50
Outstanding at March 31, 2020		1,182,629		$	14.91		9.0	$	—
Exercisable at March 31, 2020		560,524		$	30.60		8.2	$	—

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

Expected term (in years)	5.70
Risk-free interest rate	1.7	%
Expected volatility	113.7	%
Dividend yield	—