Clinical Data Support Mechanism Of Action And Patient Selection Biomarker For Imprime PGG, Biothera's Phase II Cancer Immunotherapy

Clinical findings presented at CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference

EAGAN, Minn.--(BUSINESS WIRE)--Biothera Pharmaceuticals, Inc. today announced the presentation of clinical data demonstrating the mechanism of action of Imprime PGG, the Company’s Phase 2 cancer immunotherapy drug, in healthy human volunteers. These are the first data to show that when administered intravenously to healthy human subjects, Imprime PGG drives the immunopharmacodynamic (IPD) responses observed in ex vivo human and in vivo mouse studies. Specifically, the study demonstrated that formation of an immune complex between Imprime PGG and endogenous anti-beta glucan antibodies (ABA) was critical to elicit Imprime-induced immune activating events in humans. These findings provide additional evidence that ABA levels may be a particularly useful biomarker for selecting patients most likely to respond to Imprime-based therapy. These data, as well as additional preclinical research demonstrating Imprime’s ability to reshape the suppressive immune microenvironment of the tumor and elicit robust anti-tumor immunity, were presented in poster presentations during the CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference, taking place in New York City, September 25-28, 2016.

“For the first time we are showing that Imprime PGG elicits multiple innate immune-activating events after systemic dosing in humans. These immune-activating events are the same events necessary for efficacy in preclinical models”

“For the first time we are showing that Imprime PGG elicits multiple innate immune-activating events after systemic dosing in humans. These immune-activating events are the same events necessary for efficacy in preclinical models,” said Jeremy Graff, Ph.D., Biothera’s Chief Scientific Officer and Senior Vice President, Research. “These data also further bolster our extensive research to show that pre-treatment ABA levels represent a viable, non-invasive, mechanism-based patient selection biomarker that will be deployed in our upcoming clinical trials.”

Imprime PGG is a Pathogen Associated Molecular Patterning (PAMP) molecule that acts therapeutically as an immunological “ignition switch” to enlist the functionality of the innate immune system and to enhance the efficacy of tumor targeting, anti-angiogenic, and immune checkpoint inhibitor antibodies. Biothera and Merck are advancing a phase 2 clinical research collaboration 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. Biothera and Merck are also collaborating with the Big Ten Cancer Research Consortium to commence an Imprime PGG plus KEYTRUDA Phase 1b/2 study in patients with non-small cell lung cancer.

In a second poster presentation at the conference, Biothera presented preclinical data further demonstrating the ability of Imprime PGG to re-orient the immunosuppressive tumor microenvironment, disabling the immunosuppression that shields cancer cells from immune attack. Imprime PGG promotes the differentiation of human myeloid-derived suppressor cells (MDSCs), significantly upregulating the expression of co-stimulatory molecules (iNOS, CD80, CD86) that drive anti-tumor activity and relieving MDSC-mediated inhibition of T Cell proliferation. Previous preclinical studies have reported that Imprime PGG also promotes repolarization of M2 macrophages to an anti-tumor, M1-like orientation while triggering maturation of critical antigen presenting cells (i.e. dendritic cells) to enable antigen-specific T cell expansion and the production of the potent anti-tumor cytokine interferon gamma. Collectively, these data show that Imprime PGG treatment can reshape the tumor microenvironment favoring robust anti-tumor immune responses.

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) 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.