Eisai and Merck, through a subsidiary, have formed a clinical trial collaboration to evaluate the safety, tolerability and efficacy of Merck’s anti-PD-1 therapy, pembrolizumab (marketed in the U.S. under the brand name Keytruda), in combination with Eisai oncology compounds lenvatinib mesylate (a multi-targeting RTK inhibitor marketed in the U.S. under the brand name Lenvima, lenvatinib) and eribulin mesylate (a microtubule dynamics inhibitor marketed in nearly 60 countries including Japan, the U.S. and Europe under the brand name Halaven, eribulin) in multiple clinical trials.

The planned studies include a multicenter, open-label phase Ib/II study of lenvatinib plus pembrolizumab in select solid tumors and an open-label, single-arm, multicenter phase Ib/II study to evaluate the efficacy and safety of eribulin in combination with pembrolizumab in metastatic triple-negative breast cancer. Eisai and Merck will establish a joint development committee to oversee clinical development activities. The studies are expected to begin in the second half of 2015. Financial terms of the agreement have not been disclosed.

“This collaboration could be a major step in the direction of developing combination regimens in different types of cancer, potentially maximizing the value of eribulin and lenvatinib,” said Kenichi Nomoto, Ph.D., president, oncology product creation unit, Eisai Product Creation Systems. “Together, Eisai and Merck seek to explore combination regimens that have the potential to create synergistic effects between lenvatinib and pembrolizumab as well as between eribulin and pembrolizumab. Our hope is that we will bring treatments to market that make a difference in the lives of people battling cancer.”

The combinations of lenvatinib and pembrolizumab, and eribulin and pembrolizumab, are investigational. The efficacy and safety of these combinations have not been established.