Biothera Pharmaceuticals, Inc. today announced the publication of preclinical research identifying an essential mechanism in the activation of anti-cancer immune responses by Imprime PGG, the Company’s Phase 2 cancer immunotherapy drug. The formation of an immune complex between Imprime PGG and endogenous anti-beta glucan antibodies (ABA) offers the potential to use a biomarker for selecting patients most likely to respond to Imprime-based therapy. The results were published recently in PLOS ONE, a peer-reviewed open access scientific journal, in an article titled, “Imprime PGG-mediated Anti-cancer Immune Activation Requires Immune Complex Formation.”
Imprime PGG acts as a Pathogen Associated Molecular Pattern (PAMP) that activates the innate immune system to enhance the efficacy of immune checkpoint inhibitors, as well as tumor targeting and anti-angiogenic antibodies. Imprime PGG combination therapy can trigger a robust, integrated and fully functional innate and adaptive immune response to cancer.
Utilizing whole blood from healthy human donors, Biothera researchers demonstrated that the Imprime PGG-ABA immune complexes activate and become decorated with complement (iC3b). Once formed, these three-part complexes (Imprime-ABA-complement) can then bind to and activate innate effector immune cells. However, these complexes form only in blood from donors who have sufficient levels of ABA (>20 μg/ml), and evidence of innate immune activation in response to Imprime PGG treatment is apparent only in such donors. Importantly, supplementing the whole blood from donors with insufficient ABA levels with purified ABA restores innate immune activation, which highlights the critical nature of sufficient ABA for Imprime PGG responsiveness.
“These data clearly show the necessity of ABA for responsiveness to Imprime-based therapy,” said Jeremy Graff, Ph.D., Biothera’s Chief Scientific Officer and Senior Vice President, Research. “We look forward to using ABA levels to identify these biomarker-positive patients in our upcoming Phase 2 clinical trials combining Imprime PGG and immune checkpoint inhibitors.”
Biothera plans to conduct a Phase 2 clinical trial to evaluate Imprime PGG and Merck’s anti-PD-1 inhibitor KEYTRUDA® (pembrolizumab) in patients with either advanced melanoma or metastatic triple negative breast cancer. The Big Ten Cancer Research Consortium plans to test this therapeutic combination in Phase 1b/2 study in patients with non-small cell lung cancer. Both studies are planned to open enrollment in 2016.
About Biothera Pharmaceuticals, Inc.
Biothera Pharmaceuticals is a privately held biotechnology company developing Imprime PGG, a mid-clinical stage cancer immunotherapy that orchestrates an integrated anti-cancer immune response in combination with checkpoint inhibitors and tumor-targeting and anti-angiogenesis monoclonal antibodies. Biothera and Merck have a clinical research agreement to evaluate Imprime PGG and Merck’s KEYTRUDA® (pembrolizumab) in a Phase 2 study in patients with either advanced melanoma or metastatic triple negative breast cancer. The two companies are also collaborating with the Big Ten Cancer Research Consortium on a Phase 1b/2 trial in patients with non-small cell lung cancer. Biothera also plans to conduct a Phase 2 clinical study with Imprime PGG and a checkpoint inhibitor in squamous cell carcinoma of the head and neck. Imprime PGG has been well tolerated and has established proof of concept in trials with more than 400 subjects.
KEYTRUDA® is a registered trademark of Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc.
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Last updated on: 07/11/2016
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