Biothera Pharmaceuticals Presents Translational Data from Ongoing Clinical Trials Showing Imprime PGG in Combination with Merck’s KEYTRUDA® (pembrolizumab) Drives Innate and Adaptive Immune Responses in Tumors

EAGAN, Minn., April 16, 2018 -- Biothera Pharmaceuticals, Inc. today announced the presentation of new translational data from ongoing phase 2 clinical trials combining Biothera’s Imprime PGG with KEYTRUDA^® (pembrolizumab), an anti-PD-1 therapy marketed by Merck (known as MSD outside the United States and Canada).  These data provide the first evidence in human clinical trials that Imprime PGG-based therapy can activate the immune system at the tumor site in cancer patients.  Pre- and on-treatment tumor biopsy data supporting this activity were presented in a late-breaking poster at the ongoing American Association for Cancer Research (AACR) annual meeting taking place in Chicago, IL, April 14-18, 2018.

The therapeutic combination of Imprime PGG and KEYTRUDA is being evaluated in Phase 2 clinical studies for Triple Negative Breast Cancer (TNBC) patients who have failed chemotherapy but are checkpoint inhibitor (CPI) therapy naïve, and for metastatic melanoma patients who have failed CPI therapy (ClinicalTrials.gov Identifier: NCT02981303).  As part of this phase 2 program, Biothera has obtained paired tumor biopsy samples from patients taken immediately prior to treatment and at 6 weeks “on treatment.”  Biothera’s AACR poster is based on the multispectral imaging analyses performed on seven paired biopsies (five melanoma and two TNBC), which assessed the character and quality of the immune response at the tumor site.  When compared to the pre-treatment biopsies, the “on treatment” samples consistently showed enhanced infiltration of the tumor bed by activated myeloid cells (i.e., innate immune cells), as well as CD8 and CD4 T cells.

“For the first time, we are seeing the changes in human tumors that we have routinely seen in preclinical cancer models—increased activation of both the innate and adaptive arms of the immune system following Imprime-based therapy,” said Jeremy Graff, Ph.D., Chief Scientific Officer and Senior Vice President of Research for Biothera Pharmaceuticals.  “There is a consistent repolarization of the immunosuppressive tumor microenvironment and increased T cell infiltration and activation in these on treatment biopsies.  We look forward to gaining further insights into how Imprime PGG may enhance the efficacy of KEYTRUDA and other checkpoint inhibitor therapies.”

The late-breaking poster presentation at AACR is titled, “Imprime PGG, a soluble yeast b-glucan PAMP, in combination with pembrolizumab induces infiltration and activation of both innate and adaptive immune cells within tumor sites in melanoma and triple-negative breast cancer (TNBC) patients.”  Abstract LB-129/Poster 26.

Two additional poster presentations at AACR highlighted preclinical data that expand knowledge of Imprime PGG’s mechanism of action and potential therapeutic combinations. 

• Imprime PGG, a soluble yeast b-glucan PAMP, enhancement of anti-tumor responses in combination with tumor targeting antibody is highly dependent on NK cell killing.  Abstract: 3767/Poster 17.  Biothera research now shows compelling evidence that Imprime PGG activates Natural Killer cell mediated anti-tumor efficacy when combined with tumor-targeting antibodies. 
   
• Imprime (beta-1,3/1,6 glucan) synergizes with a CD40 agonist to stimulate T cell dependent anti-tumor activity in a poorly immunogenic model of pancreatic carcinoma. Abstract: 4708/Poster 11.  Researchers at the University of Pennsylvania and Biothera combined two myeloid-directed immune agonists (Imprime PGG + CD40 antibodies) to stimulate T cell-dependent anti-tumor activity in a pancreatic cancer model.  The combination therapy induced complete and durable regressions in a majority of mice.  Tumor-free mice also resisted tumor re-challenge suggesting the establishment of immune memory. 

About Biothera Pharmaceuticals, Inc.
Biothera Pharmaceuticals is a privately held clinical stage immuno-oncology company developing Imprime PGG, a Phase 2 cancer immunotherapy that has been shown in preclinical studies to enhance the efficacy of anti-cancer immune responses in combination with immune checkpoint inhibitor, tumor-targeting and anti-angiogenic antibodies.  Biothera Pharmaceuticals has clinical research agreements with Merck to evaluate Imprime PGG and KEYTRUDA^® (pembrolizumab), Merck’s anti-PD-1 therapy, in Phase 2 studies in advanced melanoma, metastatic triple negative breast cancer and head and neck squamous cell cancer.  This therapeutic combination also is the focus of a Big Ten Cancer Research Consortium Phase 1b/2 trial in patients with non-small cell lung cancer.  In addition, Biothera Pharmaceuticals has a clinical collaboration agreement with Genentech to study Imprime PGG in combination with TECENTRIQ^® (atezolizumab) and AVASTIN^® (bevacizumab) in metastatic colorectal cancer.

KEYTRUDA^® is a registered trademark of Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, N.J., USA.

Contact:
David Walsh
Communications
Biothera Pharmaceuticals, Inc.
651-256-4606
[email protected]