Peregrine Researchers Present New Preclinical Data at AACR Annual Meeting Confirming Unique Anti-Tumor Mechanism of B...( - Bavituximab Causes Pro-Inflammatory...),Health

- Bavituximab Causes Pro-Inflammatory Effects in the Tumor Microenvironment

That May Contribute to Its Anti-Tumor Efficacy -

- Studies Show Similar Results for a New Fully Human Version of the

Antibody -

SAN DIEGO and TUSTIN, Calif., April 15 /PRNewswire-FirstCall/ -- Peregrine Pharmaceuticals, Inc. (Nasdaq: PPHM) today reported that preclinical studies being presented at the 2008 Annual Meeting of the American Association for Cancer Research (AACR) confirm a unique mechanism by which bavituximab, its lead anti-phosphatidylserine (anti-PS) antibody in Phase II cancer trials, affects the tumor microenvironment and contributes to its anti-tumor efficacy. The research, which was conducted by scientists at Peregrine, showed similar effects for bavituximab and for PGN635, a fully human version of the bavituximab antibody.

In the in vitro and in vivo studies, lead author Dr. Monica Friedrich and colleagues at Peregrine show that both bavituximab and PGN635 cause the destruction of targeted cells. They demonstrate that by blocking the anti-inflammatory signals of the phosphatidylserine found on the surface of targeted cells, these anti-PS antibodies could create a unique tumor microenvironment, by enhancing production of the pro-inflammatory cytokines TNF-alpha and GM-CSF, while decreasing production of anti-inflammatory cytokines such as interleukin 10. The studies also show that bavituximab and PGN635 promote the migration of tumor-killing macrophages and induce antibody-dependent cell-mediated cytotoxicity. In addition, the studies showed that similar to bavituximab, PGN635 localizes to tumors but not to healthy tissue.

"The AACR Annual Meeting represents an ideal oppor
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