Biothera Pharmaceuticals has announced a collaboration with Merck, known as MSD outside the U.S. and Canada, to expand the companies’ ongoing clinical program evaluating KEYTRUDA (pembrolizumab), Merck’s anti-PD-1 inhibitor, in combination with Biothera’s Imprime PGG, a Pathogen Associated Molecular Patterning molecule, or PAMP. Imprime PGG acts as an immunological “ignition switch” enlisting the innate immune system to enhance the therapeutic efficacy of tumor targeting, anti-angiogenic, and immune checkpoint inhibitor antibodies.

Under this new collaboration, a phase II clinical trial is anticipated to enroll up to 95 patients who have either advanced melanoma no longer responding to initial treatment with a checkpoint inhibitor therapy or TNBC whose disease has progressed following treatment with one or more lines of therapy for metastatic disease. Biothera will be the sponsor of the study, which is planned to begin in the fourth quarter of 2016. Merck will provide clinical supplies of KEYTRUDA for the planned studies. Other terms of the collaboration were not disclosed.

Biothera previously announced an agreement in December 2015 for Merck to supply KEYTRUDA for a phase Ib/II clinical study testing combination therapy with Imprime PGG in NSCLC patients. The Big Ten Cancer Research Consortium will conduct the multi-center trial, which is expected to commence this fall.

Barry Labinger, chief executive officer of Biothera, said, “Combination therapies with breakthrough medicines such as KEYTRUDA are potentially the next major advance in the treatment of cancer. We believe that Imprime PGG is uniquely suited to complement immune checkpoint inhibitor therapy and meaningfully enhance patient outcomes. The trial will assess safety and efficacy, as well as provide biomarker and pharmacodynamic data that will inform the design of potential phase III pivotal studies.”

Eric Rubin, M.D., vice president and therapeutic area head, Oncology Early-Stage Development, Merck Research Laboratories, commented, “As a leading innovator in the field of immuno-oncology, Merck is dedicated to advancing breakthrough science by continuing to identify novel combinations with potential to improve the care for people with cancer. We are pleased to expand our partnership with Biothera as we explore the potential for combining KEYTRUDA with their lead candidate.”