AVI BioPharma Presents Antisense Approach to Transplant Acceptance By Regulating Activated Lymphocytes

PORTLAND, Ore. — Sept. 10, 2004 — AVI BioPharma, Inc. (Nasdaq: AVII), today announced it presented data on its NeuGene® antisense approach to transplant acceptance at the 20th International Congress of the Transplantation Society, held in Vienna, Austria, Sept. 5–10, 2004.

The presentation, titled "Antisense Inhibition of cFLIP Promotes Transplant Acceptance by Sensitizing Responding T Cells to Undergo Activation Induced Apoptosis," was presented by AVI senior scientist Dan Mourich, Ph.D. The findings of the study indicate that specific transplant acceptance can be achieved using AVI’s antisense approach and that a novel method for promoting transplant survival without long-term immunosuppressive therapy is possible.

When the immune system responds to a foreign tissue transplant, specific immune cells, called lymphocytes, are activated, leading to transplant rejection. During this process a regulatory protein called cFLIP is produced, blocking apoptosis, or programmed cell death, in the activated lymphocytes.

The presentation also highlights AVI’s improved Cytoporter™ technology for selective delivery of NeuGeneS to the activated lymphocytes. When AVI used its Cytoporter technology to deliver a specific NeuGene designed to block the expression of cFLIP, the activated immune cells underwent apoptosis. This resulted in acceptance of the transplant in the animal model without nonspecific immunosuppression.

"The data presented clearly show that AVI’s NeuGene antisense drugs can be designed to selectively target activated lymphocytes and prevent transplant rejection without nonspecific immune suppression," said Patrick L. Iversen, Ph.D., senior vice president of research and development at AVI. "These results suggest that this approach has the potential to improve transplant survival in a wide variety of indications including organ, tissue, bone marrow and stem cell transplantation."

About AVI BioPharma

AVI BioPharma develops therapeutic products for the treatment of life-threatening diseases using two technology platforms: third-generation NeuGene antisense drugs and cancer immunotherapy. AVI’s lead NeuGene antisense compound is designed to target cell proliferation disorders, including cardiovascular restenosis, cancer and polycystic kidney disease. In addition to targeting specific genes in the body, AVI’s antiviral program uses NeuGene antisense compounds to target single-stranded RNA viruses, including West Nile virus, SARS coronavirus, hepatitis C virus and dengue virus. AVI’s second technology, Avicine®, is a therapeutic cancer vaccine with late-stage trials planned for the treatment of pancreatic cancer. More information about AVI is available on the company’s Web site at http://www.avibio.com.

"Safe Harbor" Statement under the Private Securities Litigation Reform Act of 1995: The statements that are not historical facts contained in this release are forward-looking statements that involve risks and uncertainties, including, but not limited to, the results of research and development efforts, the results of preclinical and clinical testing, the effect of regulation by the FDA and other agencies, the impact of competitive products, product development, commercialization and technological difficulties, and other risks detailed in the company’s Securities and Exchange Commission filings.