On October 6, 2014 Peregrine Pharmaceuticals reported the presentation of preclinical data related to the company’s immuno-oncology development program and its lead drug candidate bavituximab, a phosphatidylserine (PS)-targeting antibody (Press release Peregrine Pharmaceuticals, OCT 6, 2014, View Source [SID:1234500797]). Data show that PS-targeting agents in combination with immune checkpoint inhibitors, such as anti-PD-1 or anti-CTLA-4, promote a robust and localized anti-tumor response in models of melanoma and breast cancer and decrease levels of myeloid derived suppressor cells (MDSC) in the tumor microenvironment. Newly generated data show that the combination of a PS-targeting antibody equivalent to bavituximab administered with an anti-PD-1 antibody displayed statistically significant tumor growth suppression compared to anti-PD-1 antibody treatment alone in an animal model of melanoma. These data will be presented this morning at the Cancer Research Institutes’ “Cancer Immunotherapy: Out of the Gate” conference being held at the Grand Hyatt Hotel in New York, New York.
“We are pleased to be presenting this exciting data to this immuno-oncology focused audience,” said Jeff T. Hutchins, Ph.D. vice president, preclinical research at Peregrine Pharmaceuticals “These data are impressive and consistent in their findings across several tumor types and further build on the rationale for additional collaborative studies such as the ongoing investigator-sponsored Phase Ib trial of bavituximab in combination with ipilimumab (Yervoy) in advanced melanoma.”
The poster titled: “Antibody-mediated blockade of phosphatidylserine enhances the anti-tumor activity of immune checkpoint inhibitors by affecting myeloid-derived suppressor cell (MDSC) and lymphocyte populations in the tumor microenvironment” will be presented by Rolf Brekken, Ph.D., Effie Marie Cain Research Scholar in Angiogenesis Research and an Associate Professor, in the Departments of Surgery and Pharmacology at the Hamon Center for Therapeutic Oncology Research, University of Texas Southwestern Medical Center in Dallas, Texas. Data from these studies show that the PS-targeting antibody ch1N11, the preclinical equivalent to bavituximab, significantly enhances tumor growth inhibition of anti-CTLA-4 or anti-PD-1 in the B16 and K1735 melanoma models and the efficacy of anti-PD-1 in the EMT-6 breast tumor model. New data show that the combination of ch1N11 and an anti-PD-1 antibody produce a statistically significant difference (p=0.018) in tumor growth suppression over anti-PD-1 alone in the B16 melanoma model. In addition, PS blockade with ch1N11 combined with either anti-CTLA-4 or anti-PD-1 resulted in greater T cell infiltration into B16 and K1735 tumors than tumors treated with either antibody alone. Consistent with these results, ch1N11 combined with anti-PD-1 showed an enhanced percentage of T cells producing the cytokines IL-2 and IFNg, factors associated with immune activation, when compared with T cells from tumors being treated with anti-PD-1 alone. In summary, the targeting and blocking of PS with ch1N11 significantly improved the anti-tumor efficacy of immune checkpoint blockade in robust models of melanoma and breast cancer in immunocompetent animals.