AVI BioPharma Inc. Announces Additional Data From Multi-Center Phase II Study of AVICINE in Advanced Colorectal Cancer.

PORTLAND, Ore.--(BW HealthWire)--May 26, 1999--

- New Data Suggests Increased Survival Linked To

Dual Antibody Response -

AVI BIOPHARMA INC. ("AVI")(Nasdaq: AVII, AVIIW), at its annual meeting of shareholders, today announced analysis of additional clinical data from its multi-center Phase II clinical trial of AVICINE(TM), a therapeutic cancer vaccine, in advanced colorectal cancer. This data builds upon previously announced results gathered from a two-year clinical trial of AVICINE in 77 patients with metastatic colorectal cancer. Overall, 51 of the 77 patients demonstrated an immune response to human chorionic gonadotropin (hCG), with a median survival of 42 weeks. The additional data suggests that patients who responded to both targets (epitopes) of the hCG peptide (CTP-37) experienced a median survival of approximately 65 weeks, compared to a median survival rate of 39 weeks for Pharmacia-Upjohn's FDA approved drug, Camptosar(R).

Intensive investigation over the past six months found that the vaccine peptide is composed of two epitopes, one of which is dominant. The dominant epitope orchestrates a single antibody response in approximately half of the patients. The balance of the patients responded to both epitopes (dual response). This dual response correlated with a statistically significant survival benefit (65 weeks) compared to a single antibody response (35 weeks), or standard chemotherapy with Camptosar. The new data support the addition of a second hCG peptide to the vaccine formulation in order to modulate immunological dominance. Overall, these data suggest that patient survival is linked to hCG antibody response, with dual responses providing a significantly more favorable outcome than responses to a single epitope. The inclusion of a second hCG peptide in the Company's AVICINE formulation is expected to increase immunological response to multiple epitopes resulting in improved patient survival.

Denis R. Burger, Ph.D. AVI's President and CEO, stated, "Based upon the new data, we are encouraged to go one step further in our development efforts in order to make AVICINE a more potent vaccine. Specifically, we have formulated a new vaccine that contains an additional hCG peptide domain, referred to as the loop peptide. The addition of the loop peptide modulates the dominance of the past formulation, resulting in a strong, balanced antibody response. Simply by adding an additional peptide we are able to force the immune system into responding to multiple epitopes, which leads to improved survival. The FDA has reviewed the new AVICINE formulation and AVI plans to use the new formulation in our upcoming clinical trials."

AVICINE, a therapeutic cancer vaccine, is AVI BioPharma's lead product candidate. AVICINE elicits a highly specific immune response to the human hormone and growth factor hCG, a cancer-associated oncofetal protein. AVICINE is essentially a non-toxic immunotherapy and has been evaluated in five clinical trials. To date, 174 patients have been treated. Early studies have provided evidence of objective tumor responses and apparent survival benefits in patients who have failed conventional therapy.

AVI BioPharma Inc. is dedicated to the development and commercialization of products for the treatment of life-threatening diseases using three technology platforms: immunotherapy for cancer, gene-targeted drugs and intracellular drug delivery technology. Its lead clinical agent, AVICINE(TM), an essentially non-toxic cancer vaccine, soon will enter a Phase III licensing trial in colorectal cancer, a Phase II trial in pancreatic cancer and a Phase II trial in prostate cancer. The company has also developed a patented class of gene-targeted drugs called NEUGENES(R), which may be useful in the treatment of a wide range of human diseases including cardiovascular restenosis and cancer. Further, AVI has developed a novel drug delivery technology, called CYTOPORTER(TM), which may be useful in significantly improving drug uptake, while minimizing toxicity, for a wide range of FDA approved drugs.

"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 pre-clinical 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.