Peregrine Pharmaceuticals Reveals Preclinical Data on PS-Targeting Antibodies, Anti-PD-1 Antibodies

Peregrine Pharmaceuticals Reveals Preclinical Data on PS-Targeting Antibodies, Anti-PD-1 Antibodies

PeregrinePeregrine Pharmaceuticals Inc. will announce its preclinical data validating the potent immune-stimulatory mechanism of its phosphatidylserine (PS)-targeting immuno-oncology platform at the 9th Annual Immunotherapies and Vaccine Summit being held August 11-14, 2014 in Boston, Massachusetts.

PS is a highly immunosuppressive molecule that tumors use to escape immune surveillance. Bavituximab is a monoclonal antibody developed by Peregrine that targets PS and counteracts its pro-tumoral effect while at the same time activating anti-tumor immune cells that can recognize and eliminate cancer.

This investigational drug is the subject of the SUNRISE pivotal Phase III clinical trial, evaluating its efficacy and safety as a second-line treatment for patients with Stage IIIb/IV non-squamous non-small cell lung cancer (NSCLC). Additionally, it is also being tested in several solid tumors such as breast cancer, liver cancer, rectal cancer and advanced melanoma, having received a Fast Track designation by the U.S. Food and Drug Administration (FDA) for the potential treatment of second-line non-small cell lung cancer.

The presentation, titled “Phosphatidylserine (PS)-Targeting Antibodies Enhance Activity of Immune Checkpoint Inhibitors by Repolarizing Immunosuppressive Immune Cells Populating the Tumor Microenvironment” will be done by Jeff Hutchins, Ph.D., vice president of preclinical research at Peregrine and will show that in a mouse model of breast cancer, combining a PS-targeting antibody (ch1N11) equivalent to bavituximab, with an anti-PD-1 antibody, significantly suppressed tumor growth by 78.7% when compared to anti-PD-1 alone.

Additionally, administration of ch1N11 plus the anti-PD-1 antibody led to a 78% and 81% increase in intratumoral CD4+ and CD8+ T cells, compared to the single agent, demonstrating a preferential recruitment of anti-tumor T cells upon combination therapy.

“These statistically significant results are an important extension of earlier data obtained combining our PS-targeting antibodies with other immune checkpoint inhibitors in different tumor types and our clinical experience in treating breast cancer patients,” said Dr. Hutchins in the company’s press release. “These data further validate that blocking the immunosuppressive effects of PS facilitate an increase in tumor-fighting T-cells, and that the combination with PD-1 then allows for a more effective anti-tumor T-cell response. We believe these studies, along with our previously released Phase II breast cancer results, warrant an expanded clinical investigation in breast cancer that would build on our ongoing immunotherapy combination clinical trial in advanced melanoma.”

In the same press release, Bruce Freimark, Ph.D., director of pre-clinical research in oncology also added “With these combination results, we are clearly seeing both a significant delay in tumor growth as a group and a decrease in the number of animals with tumor progression. We believe these data present encouraging observations to support the expanded clinical use of tumor immunotherapy combinations using PS-targeting antibodies”.