Biothera’s Imprime PGG And Monoclonal Antibody Therapy Alleviates Immune Suppression In Tumor Microenvironment And Increases Cancer Cell Killing

Company to Present New Preclinical Data at Society for Immunotherapy of Cancer Annual Meeting

NATIONAL HARBOR, Md.--(BUSINESS WIRE)--New research provides additional scientific evidence that Biothera’s mid clinical stage cancer immunotherapy Imprime PGG acts as an immune ignition switch that enables the body to recognize and kill tumor cells. The company will present the data today at the Society for Immunotherapy of Cancer annual meeting.

“These new data show for the first time that Imprime PGG, particularly in combination with anti-angiogenic antibodies, can effectively re-orient the immune microenvironment within tumor tissues.”

Imprime PGG is a first-in-class, well-tolerated, systemically administered beta glucan PAMP (pathogen associated molecular pattern) that orchestrates a fully integrated immune response to enhance the efficacy of tumor-targeting and anti-angiogenic antibodies as well as checkpoint inhibitors.

Numerous studies have shown that tumors suppress the body’s immune responses to enable cancer cell survival and growth. Previous in vitro research found that Imprime PGG could re-orient the immunosuppressive capability of M2 macrophages, one of the key monocyte-derived cells within the tumor microenvironment. New data demonstrates this same effect in vivo at the tumor site, as evidenced by re-orientation of the behavior of M2 macrophages within tumor tissue.

“The effectiveness of immunotherapies is often stymied by the suppressive nature of the immune system at the tumor site. Overriding this suppressive nature is critical to realize the potential of immunotherapy,” said Jeremy Graff, Ph.D., Chief Scientific Officer and SVP, Research, Biothera Pharmaceutical Inc. “These new data show for the first time that Imprime PGG, particularly in combination with anti-angiogenic antibodies, can effectively re-orient the immune microenvironment within tumor tissues.”

In Biothera’s recent study, mice injected with non-small cell lung cancer cells were treated with the anti-angiogenic monoclonal antibody bevacizumab (Avastin^®) alone or in combination with Imprime PGG after tumors reached a group mean of ~100mm. Following treatment, tumor and spleen tissues were harvested to assess the status of the tumor immune microenvironment. Compared with mice treated with bevacizumab alone, those treated with bevacizumab and Imprime PGG showed:

• Significant increases in CD86 -- a critical immune activation marker -- with a concomitant decrease in a common marker of immunosuppression, Arginase-1, in splenic macrophages.
• Significant increases in the production of TNFa following ex vivo treatment with LPS.
• A significant reduction in the potent immunosuppressive factor TGFß specifically in tumors with the greatest reduction in tumor size.

The Biothera poster presentation will be held today from 12:45 pm to 2:00 pm. The abstract is titled: Imprime PGG, an innate immunomodulator for cancer immunotherapy, has the potential to modulate macrophages in the tumor and the spleen to an anti-tumor M1-like phenotype. Authors: Kathryn Fraser, Nadine Ottoson, Xiahong Qiu, Anissa SH Chan, Adria Jonas, Takashi Kangas, Jeremy Graff, Nandita Bose.

About Biothera
Biothera is a privately held biotechnology company developing Imprime PGG, a first-in-class cancer immunotherapy that orchestrates an integrated anti-cancer immune response in combination with tumor- and angiogenesis-targeting monoclonal antibodies. Proof of concept has been established from single-arm and randomized phase 2 studies in non-small cell lung cancer (NSCLC), colorectal cancer, and chronic lymphocytic leukemia. Studies are ongoing in metastatic colorectal cancer and non-Hodgkin lymphoma. More information is available at www.biothera.com/pharma or follow us on Twitter.