Note 7 - Commitments and Contingencies (Details Textual)		1 Months Ended		3 Months Ended		6 Months Ended
	Mar. 16, 2020 USD ($)	Jun. 30, 2022 USD ($)	Feb. 28, 2022 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)
Lessee, Operating Lease, Monthly Rent Average Increase Rate		3.00%
Sublease Income				$ 10,000	$ 10,000	$ 21,000	$ 21,000
Operating Lease, Payments				35,000	34,000	70,000	68,000
License Agreements Expense				56,000	56,000	133,000	94,000
Research and Development Expense, Total				4,204,000	3,039,000	8,824,000	7,145,000
MD Anderson [Member]
Payments For Research And Development Agreement		$ 1,300,000
Research and Development Expense, Total				313,000	184,000	500,000	278,000
Dermin [Member]
Payments for Termination of Commitment			$ 400,000
License Terminations Expense				0	0	400,000	0
Houston Pharmaceuticals, Inc [Member]
Related Party Transaction, Expenses from Transactions with Related Party				$ 59,000	$ 59,000	$ 117,000	$ 117,000
Houston Pharmaceuticals, Inc [Member] | Consulting Agreement on Licensed Molecules [Member]
Other Commitments, Number of Agreements	2
Other Commitment, Total	$ 43,500
Houston Pharmaceuticals, Inc [Member] | Agreement Providing Access to Laboratory Equipment [Member]
Other Commitment, Total	$ 15,000
Other Commitments, Cancellation Period (Day)	60 days