Note 6 - Stock-based Compensation (Tables)

9 Months Ended

Sep. 30, 2020

Notes Tables

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

	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2019		2020		2019
Research and development	$	19,838	$	13,519	$	136,236	$	40,692
General and administrative		259,635		131,802		448,061		344,913
Total stock-based compensation expense	$	279,473	$	145,321	$	584,297	$	385,605

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)
Balance at January 1, 2020		309,276		$	55.78
Granted		1,731,100			0.66
Expired		(172	)		142.50
Outstanding at September 30, 2020		2,040,204		$	9.01		9.1
Exercisable at September 30, 2020		992,779		$	17.65		8.4

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

	2020			2019
Expected term (in years)		7.75			5.52
Risk-free interest rate		0.9	%		2.2	%
Expected volatility		119.7	%		113.4	%
Dividend yield		—	%		—	%