AVI BioPharma Announces Initiation of Acute West Nile Virus Clinical Study; FDA Protocol Review Leads to Initiation of Safety and Efficacy Study.

PORTLAND, Ore. -- AVI BioPharma, Inc. (Nasdaq:AVII) today announced it will initiate a clinical trial with its NEUGENE antisense drug candidate, AVI-4020, for the treatment of patients with acute West Nile virus disease who have serious neurological impairment (WNV neuroinvasive disease). A number of clinical sites located in Arizona and Southern California are expected to participate in this study with the possibility of increasing the number of sites elsewhere based upon disease outbreaks.

"This clinical trial has been designed to provide an additional demonstration of AVI-4020's safety and an opportunity to evaluate potential efficacy of our NEUGENE antisense drug against WNV," said Denis R. Burger, Ph.D., chief executive officer of AVI. "We are encouraged by the pilot AVI-4020 clinical trial conducted last fall, which met its primary safety endpoints. Moreover, the pharmacokinetic profile of AVI-4020 indicated that delivery across the blood-brain barrier was achieved in all patients, which may be crucial for those with neurological impairment."

In the upcoming double-blind, multicenter study, 50 patients presenting with presumptive acute WNV neuroinvasive disease will be randomized into two cohorts. Forty patients will receive AVI-4020 for five days at a daily dose of 90 mg, and 10 patients will receive a placebo for five days. The patients will be monitored on a daily basis for safety and disease progression and resolution for seven to 10 days, and then periodically for six months. Interested parties should contact AVI directly for further study information. Within the next few weeks, information pertaining to this study will be located on the CDC Web site at www.cdc.gov/ncidod/dvbid/westnile/clinicalTrials.htm and http://www.clinicaltrials.gov.

Last fall, AVI conducted a pilot WNV clinical study enrolling 10 patients, nine of whom received AVI-4020 at daily doses of 30 mg for five days, and one of whom received a placebo. The focus of that trial, conducted in Colorado at Boulder Community Hospital, was to initially evaluate safety and pharmacokinetic parameters of AVI-4020. The data demonstrated the safety of AVI-4020 by clinical and laboratory criteria. All patients who received the drug were found to have AVI-4020 in the cerebrospinal fluid by the fifth day after starting treatment.

"The continued spread of West Nile virus in the United States and lack of any existing therapies necessitates further research into compounds with the potential to treat this devastating and sometimes fatal disease," said Nelson Gantz, M.D., chief of Infectious Diseases at the Boulder Community Hospital and an investigator in both clinical studies of AVI-4020. "The results we have seen with this compound so far are encouraging and merit further study in a larger setting. The new study is designed to further elucidate the potential of this therapy in West Nile virus, an urgent unmet medical need."

Earlier this season, a patient with WNV neuroinvasive disease was treated with AVI-4020 under an emergency investigational new drug (IND) application using the dosing protocol from the upcoming trial. Dosing was three times that used in the 2003 clinical trial and approximately three times more AVI-4020 was detected in the patient's cerebralspinal fluid. Clinical assessment of the patient was consistent with benefit from the drug; however, this observation is considered anecdotal until more patients are studied.

AVI believes its NEUGENE antisense rapid response therapeutics have a significant role to play in the future of antiviral therapeutics, especially in combating emerging infectious diseases that threaten public health or in combating bioterrorism. AVI can produce clinical-grade antiviral therapeutics to targeted viral pathogens within days, if necessary, to respond to public health and bioterrorist threats. NEUGENES are synthetic compounds that mirror a critical portion of a disease-causing organism's genetic code and bind to specific portions of the target genetic sequence. Like a key in a lock, NEUGENE antisense compounds are designed to match up precisely with a specific gene or viral sequence, blocking the function of the target gene or virus.

About West Nile Virus (WNV)

To date in 2004, according to the Centers for Disease Control and Prevention, 922 cases of West Nile virus infection were reported, resulting in 22 deaths. Most people who become infected with WNV have no symptoms, although about 20 percent develop mild, flu-like symptoms, including fever, headache, body aches and, occasionally, a rash and swollen lymph glands. In its most serious manifestations, which occur in one out of 30 symptomatic cases of WNV disease, WNV infection may cause life-threatening inflammation of the brain (encephalitis) or inflammation of the membrane surrounding the brain and spinal cord (meningitis), as well as a number of other significant neurological symptoms, including muscle paralysis similar to that seen with poliovirus and other viruses that cause acute flaccid paralysis.

More information about West Nile virus can be found at the CDC Web site, http://www.cdc.gov/ncidod/dvbid/westnile/index.htm.

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, Ebola virus, SARS coronavirus, hepatitis C virus, and dengue virus. AVI's second technology, Avicine(R), 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.