Since the initial data demonstrating bavituximab's immunotherapy mechanism were presented earlier this year, we have undertaken preclinical studies to actively explore new combinations and approaches for potential bavituximab therapies," said Jeff T. Hutchins, Ph.D. vice president, preclinical research of Peregrine Pharmaceuticals. "As immunotherapy combinations have shown great promise recently in treating cancer and as PS is known to be a primary upstream inhibitory checkpoint for tumor immune recognition, we believe there are many immunotherapy combination options for bavituximab. As such, our ongoing preclinical studies are designed to read out in the coming months to guide our clinical trial development strategy for these combinations."
These results appear in the American Association for Cancer Research (AACR) peer-reviewed journal, Cancer Immunology Research, in a manuscript titled: "Phosphatidylserine-targeting antibody induces M1 macrophage polarization and promotes myeloid derived suppressor cell differentiation."
In the online released manuscript, researchers examined whether 2aG4, the mouse equivalent antibody to bavituximab, could reverse the known immunosuppressive effects of exposed PS in the tumor environment. Results showed that 2aG4 reactivated antitumor immunity on multiple levels including the switching of tumor associated macrophages to a tumoricidal M1-like phenotype, the reduction of myeloid-derived suppressor cells (MDSC) in tumors, an increase in immunostimulatory signaling chemicals (cytokines) and the maturation of dendritic cells into functional antigen-presenting cells (APC) leading to tumor-specific cytotoxic T-cell responses. These multiple anti-tumor effects were further shown to occur without the side-effects associated with systemic immune activation.