Note 10 - Subsequent Event	6 Months Ended
Jun. 30, 2021
Notes to Financial Statements
Subsequent Events [Text Block]	10. Subsequent Event In July 2021, the Company received notice that it achieved a $3 million development milestone from its licensee, 3D Medicines Inc. This milestone is based on the Center for Drug Evaluation (CDE) of the China National Medical Products Administration (NMPA) approval of the IND application submitted by 3D Medicines Inc. to participate in the Company’s international AVB-500 Phase 3 PROC clinical trial.

The entire disclosure for significant events or transactions that occurred after the balance sheet date through the date the financial statements were issued or the date the financial statements were available to be issued. Examples include: the sale of a capital stock issue, purchase of a business, settlement of litigation, catastrophic loss, significant foreign exchange rate changes, loans to insiders or affiliates, and transactions not in the ordinary course of business.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 855
-URI http://asc.fasb.org/topic&trid=2122774

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 855
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6842918&loc=SL6314017-165662

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