Array BioPharma, a biopharmaceutical company, has entered into a clinical trial collaboration agreement with Merck (known as MSD outside the United States and Canada) to investigate the safety and efficacy of Array's MEK inhibitor, binimetinib, with Merck's anti-PD-1 therapy, Keytruda (pembrolizumab), in metastatic colorectal cancer patients with microsatellite stable tumors (MSS CRC).

The companies are entering into this collaboration based on the growing body of preclinical and clinical evidence that the immune activity of an anti-PD-1 therapy, such as Keytruda, can be enhanced when combined with a MEK inhibitor, such as binimetinib.

"Array is excited to announce this partnership with Merck, an established leader in the field of immuno-oncology," said Ron Squarer, chief executive officer, Array BioPharma. "Given the synergistic activity we have seen with our MEK inhibitor when combined with anti-PD-1 therapy in preclinical models, and based on emerging clinical data, we are optimistic that this combination holds great potential for cancer patients."

Under the terms of the agreement, Array and Merck will collaborate on a clinical trial to investigate the safety and efficacy of the combination of binimetinib with Keytruda, in MSS CRC patients. The trial is expected to establish a recommended dose regimen of binimetinib and Keytruda, as well as explore the preliminary anti-tumor activity of several novel regimens. The study is expected to begin in the second half of 2017. Results from this first study will be used to determine optimal approaches to further clinical development of these combinations.

The collaboration agreement is between Array BioPharma and Merck, through a subsidiary. Under the agreement, the trial will be sponsored by Merck.  Additional details of the collaboration were not disclosed.