Bavituximab
Complete Inhibition of Viral Replication in H5N1 In Vivo Model by Bavituximab
By Peregrine Pharmaceuticals
May 25, 2006 - 1:09:00 PM

Peregrine Pharmaceuticals, Inc. (Nasdaq: PPHM), a biopharmaceutical company with a portfolio of innovative, clinical stage product candidates for the treatment of hepatitis C virus (HCV) infection and cancer, today announced that its lead anti-viral compound bavituximab (formerly Tarvacin) completely inhibited replication of a laboratory strain of the H5N1 virus, commonly known as avian flu, in fertilized chicken eggs, an in vivo model for influenza anti- viral activity. These preliminary findings will be reported today at the 106th general meeting of The American Society for Microbiology (ASM) in Orlando, Florida by Dr. Philip Thorpe, a member of the Peregrine Scientific Resource Board and professor of pharmacology at the University of Texas Southwestern Medical Center at Dallas. Bavituximab, a monoclonal antibody with unique anti-viral and anti-cancer properties, has already demonstrated good tolerability in a Phase l trial in patients with HCV infection.

"This first set of results showing that bavituximab appears to have inhibited H5N1 viral replication in the fertilized egg model and the supportive data confirming that bavituximab binds to H5N1 viral particles are encouraging," said Dr. Thorpe. "These early data support the view that bavituximab may be active against H5N1 and other common strains of influenza."

The H5N1 studies reported by Dr. Thorpe were conducted at a number of independent research laboratories. Peregrine has also been collaborating with other researchers to evaluate the potential of bavituximab delivered by different routes of administration to treat infections caused by influenza A, the viral family that includes the H5N1 strain. Peregrine has ongoing studies to evaluate various delivery methods and treatment regimens to treat influenza in a number of in vivo models, including well-established mouse and ferret models. These studies include assessments of bavituximab delivered by nasal inhalation, a form of delivery expected to be more effective than systemic delivery alone for respiratory viruses that lodge deep in the lungs.

"These early experimental data suggesting that bavituximab may have activity against the avian flu, along with preliminary data recently generated showing signs of activity in a ferret model of influenza A infection, give us momentum and direction as we pursue a variety of preclinical initiatives to assess the anti-viral potential of bavituximab," said Steven W. King, president and CEO of Peregrine. "With a repeat dose safety study in HCV patients expected to begin next month, we should be well-positioned to initiate clinical trials for bavituximab in additional indications once we have sufficient preclinical data in hand."

Bavituximab is an antibody that attaches to specific cellular components called phospholipids found on the surface of virus particles, including influenza and certain other virus strains, as well as on the outer surface of human host cells only when they are infected with these viruses. Bavituximab helps stimulate the body's natural immune defenses to destroy both the virus particles and the infected cells, without affecting healthy cells. Bavituximab is in Phase 1 clinical trials for hepatitis C virus infections and for solid tumor cancers. A Phase 1b repeat dose study in HCV patients is expected to start in June.

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