Peregrine's Bavituximab in Combination With Anti-CTLA-4 Antibodies Yields Enhanced Anti-Tumor Activity in Pre-Clinical Model of Melanoma

Peregrine Pharmaceuticals

today announced the presentation of data at the Society for Immunotherapy of Cancer (SITC) Annual Meeting in National Harbor, Maryland being held November 7-10. The data showed that phosphatidylserine (PS)-targeting antibodies reactivate tumor immunity at multiple levels and that these antibodies, when combined with an anti-CTLA-4 antibody, an FDA-approved immunotherapy, yielded enhanced anti-tumor activity in a pre-clinical model of melanoma. Peregrine is planning to initiate a Phase III clinical trial in second-line non-small cell lung cancer with its lead PS-targeting antibody bavituximab by year-end. In the presentation titled: "Targeting of Phosphatidylserine by Monoclonal Antibodies Induces Innate and Specific Anti-tumor Responses," scientists from Peregrine and The University of Texas Southwestern Medical Center examined the anti-tumor response of a PS-targeting antibody equivalent to bavituximab and anti-CTLA-4 combination therapy in a mouse melanoma model. Results showed that the group (n=12) that received the combination resulted in superior tumor growth inhibition than with either antibody alone with no additional toxicity following multiple treatment doses. In addition, histopathological analysis showed the combination produced more inflammatory cell infiltration and tumor destruction than anti-CTLA-4 alone. "The results presented at SITC demonstrate that PS-targeting antibodies can block PS-mediated immunosuppression while simultaneously activating the immune system and that these effects can greatly improve the number of subjects responding to anti-CTLA-4 immunotherapy," said Jeff T. Hutchins, Ph.D., vice president of preclinical research at Peregrine. "We believe the encouraging preclinical combination treatment data are due in part to the ability of bavituximab to facilitate an increase in tumor-specific cytotoxic T-cell activity, a function that appears to expand and broaden the potential of immunotherapeutic agents including anti-CTLA-4 and anti-PD-1 which prime and sustain T-cell mediated killing of tumor cells in our pre-clinical models. We are continuing to explore these and other immunotherapy combinations and look forward to reporting additional results as they become available."