Peregrine Pharma (PPHM) to Present Statistically Significant Data on PS-Targeting Antibody Combo
Source: Street Insider.com., November 2014
Peregrine Pharma (NASDAQ: PPHM) announced the first of four presentations of clinical and preclinical data related to the company’s immuno-oncology development program and its lead investigational immunotherapy drug candidate bavituximab. Data from today’s presentation show that the combination of a phosphatidylserine (PS)-targeting antibody equivalent to bavituximab and an antibody targeting the immune checkpoint CTLA-4 yielded statistically significant anti-tumor effects as compared to the anti-CTLA-4 antibody alone. In addition, this combination decreased levels of Arg1, a molecule predominantly expressed by myeloid derived suppressor cells (MDSC) and M2 macrophages; two key cell types that contribute to immunosupressive activity in animal models of melanoma. This presentation will be made at the Society for Immunotherapy of Cancer’s (SITC) 29th Annual Meeting and Associated Programs being held November 6-9, 2014 at the Gaylord National Hotel and Convention Center in National Harbor, Maryland.
The poster titled: “Antibody-mediated Blockade of Phosphatidylserine Enhances the Anti-tumor Activity of Immune Checkpoint Inhibitor anti-CTLA-4 by Affecting Myeloid Derived Suppressor Cells (MDSC) and Lymphocyte Populations in a Melanoma Tumor Microenvironment" will be presented in a poster session on Friday, November 7, 2014 by Bruce Freimark, Ph.D., director, preclinical research, oncology at Peregrine Pharmaceuticals. Dr. Freimark’s presentation will review preclinical data demonstrating that animals treated with the PS-targeting antibody ch1N11, the preclinical equivalent to bavituximab, in combination with anti-CTLA-4 in melanoma models demonstrated statistically significant (p=0.0019) delayed tumor growth and suppression compared to anti-CTLA-4 alone. New data presented today show the expression of Arg1 is decreased in K1735 tumors treated with ch1N11 alone or in combination with anti-CTLA-4 compared with anti-CTLA4 or control antibody. In addition, using immunohistochemistry, the ratio of CD8/CD3 T cells is increased in tumors from animals administered the combination of ch1N11 and anti-CTLA-4 compared to tumors from animals administered control antibodies.
Dr. Freimark said: “These statistically significant data show that the combination of a PS targeting antibody and the immune checkpoint inhibitor, anti-CTLA-4, achieved a superior tumor immune response over anti-CTLA-4 alone. It is gratifying to see the immunostimulatory mechanism of action of PS-targeting antibodies that our colleagues at UT Southwestern published utilizing tumor zenograft models is robustly translating to our immune competent models of melanoma in mice; particularly when it comes to lowering the levels of MDSCs and M2 macrophages in the tumor microenvironment. These data further support the mechanism of action of bavituximab and strengthen the pre-clinical rationale for an ongoing Phase Ib evaluation of bavituximab in combination with the approved CTLA-4 inhibitor Yervoy? in patients with advanced melanoma; highlighting our belief that the combination of upstream and downstream checkpoint inhibitors could improve overall response rates."
Peregrine today also announced that the following poster presentations will be made during sessions tomorrow, Saturday, November 8, 2014.
Title: Correlative Studies of a Phase II Clinical Study of Bavituximab and Sorafenib in Patients with Advanced Hepatocellular Carcinoma Presenter: Nikoletta Lea Kallinteris, M.Sc., CCRP, senior scientist, translational research at Peregrine Pharmaceuticals, Inc. Poster No.: P236 _________________________ Title: Antibody-mediated Blockade of Phosphatidylserine Enhances the Anti-tumor Activity of Immune Checkpoint Inhibitor a-PD-1 by Affecting Myeloid Derived Suppressor Cells (MDSC) and Lymphocyte Populations in a Breast Tumor Microenvironment Presenter: Bruce Freimark, Ph.D., director, preclinical research, oncology at Peregrine Pharmaceuticals, Inc. Poster No.: P228 _________________________ Title: Antibody-mediated Blockade of Phosphatidylserine Enhances the Anti-tumor Activity of Immune Checkpoint Inhibitor anti-PD-1 by Affecting Myeloid Derived Suppressor Cells (MDSC) and Lymphocyte Populations in a Melanoma Tumor Microenvironment Presenter: Xianming Huang, Ph.D., assistant professor, Hamon Center for Therapeutic Oncology, Pharmacology, Simmons Comprehensive Cancer Center University of Texas Southwestern Medical Center, Dallas, Texas. Poster No.: P226
In addition to these poster presentations, Peregrine will be hosting conference attendees at Booth #117 located in Prince George’s Exhibition Hall C.