Biothera enhances innate immune responses to Imprime PGG drug candidate

Biothera has enhanced innate immune responses to its cancer immunotherapy drug candidate Imprime PGG^® in subjects regardless of biomarker status, demonstrating the opportunity to treat a larger patient population. The in vitro research will be presented today at the Cambridge Healthtech Institute's Antibody-Drug Conjugates/Engineering Targeted Therapeutics conference in Palm Springs, CA.

Biothera developed an Imprime PGG-antibody conjugate that induced similar immune modulation effects in immune cells from biomarker-negative subjects as Imprime PGG alone does in biomarker-positive subjects. By attaching or conjugating antibodies directly to Imprime PGG, the combination was able to bind to innate immune cells and initiate biological activity. This includes the production of beneficial chemokines that are necessary for neutrophils and monocytes to join the fight against cancer.

"This research shows that there is an opportunity to significantly expand the cancer patient population that can respond to Imprime PGG therapy, regardless of biomarker status," said Dan Conners, president of Biothera's Pharmaceutical Group. "Our previous research demonstrated the potential for Imprime PGG combination therapy to treat a wide range of cancer types and the results of our proof-of-concept clinical trials are confirming that in the biomarker-positive patient population. Now, we are confident that this treatment option can be made to work in the vast majority of cancer patients."

Biothera recently reported the results of its Phase 2 clinical trial evaluating the effectiveness of its experimental cancer immunotherapy Imprime PGG in combination with cetuximab (Erbitux^®), carboplatin and paclitaxel compared with the monoclonal antibody and chemotherapies alone in previously untreated patients with advanced non-small cell lung cancer. During the study, Biothera researchers discovered a biomarker that identified subjects who were most likely to best respond to Imprime PGG. The objective overall response rate, the primary endpoint of the study, was 67% for biomarker-positive patients compared with 23% for the control group patients. The median overall survival for biomarker-positive patients was 16.5 months compared with 11.2 months for the control group patients.

The predictive biomarker that identifies which patients would respond best to Imprime PGG is a naturally occurring antibody to Imprime PGG. These antibodies bind to Imprime PGG forming an antibody-Imprime PGG complex that is required for binding to innate immune cells that the drug engages and directs to recognize and kill antibody-targeted cancer cells. Using a quantitative serum assay, Biothera can determine which patients are biomarker positive for these naturally occurring antibodies and may respond to Imprime PGG. Biomarker-negative patients, however, lack sufficient levels of the necessary antibodies for their innate immune cells to respond to Imprime PGG therapy.

Michael E. Danielson, Ph.D., Biothera senior director of Chemistry Research, will present the company's new research at 9:35 am PST today in room B201 at the Renaissance Hotel and Palm Springs Convention Center. The presentation is entitled, "The Use of Carbohydrate Antibody Conjugates to Stimulate and Direct Innate Immune Cells to Recognize and Kill Cancer Cells." The authors are Biothera researchers Michael E. Danielson Ph.D., Nandita Bose Ph.D., Kyle S. Michel, Xiaohong Qiu, Nadine C. Ottoson, Mary Antonysamy, Ph.D., Andrew S. Magee, Ph.D., and Paul M. Will.

SOURCE Biothera, the Immune Health Company