Pfizer and Merck & Co., known as MSD outside the United States and Canada, through a subsidiary, have entered into an agreement to explore the therapeutic potential of the combination of Pfizer’s crizotinib (Xalkori) with Merck’s investigational anti-PD-1 antibody pembrolizumab, in a phase 1b clinical study evaluating the safety and tolerability of the combination in patients with ALK-positive advanced or metastatic non-small cell lung cancer (NSCLC).  The financial terms of the agreement were not disclosed.

“This collaboration between Pfizer and Merck is just one example of the willingness of sponsors to work together in an effort to accelerate progress against some of the most difficult-to-treat cancers,” said Dr. Mace Rothenberg, senior vice president of clinical development and medical affairs and chief medical officer for Pfizer Oncology.  “Understanding the effects of combining one drug, Xalkori, which inhibits an abnormally activated enzyme in patients with ALK-positive metastatic lung cancer, with the investigational drug, pembrolizumab, which harnesses the body’s immune system to fight cancer, is vital if we are to continue to advance the care of lung cancer patients.”

This multi-centre, open-label clinical study is expected to begin in 2015. Pfizer will conduct the study.

“We are pleased to build upon our ongoing collaboration with Pfizer to evaluate potential combination regimens incorporating Merck’s investigational immunotherapy pembrolizumab,” said Dr. Eric Rubin, vice president, Oncology, Merck Research Laboratories.  “Evidence from early studies of pembrolizumab monotherapy together with Xalkori’s proven targeted therapeutic approach provides the scientific rationale for evaluating this combination for the treatment of lung cancer.”

Both companies previously announced plans to evaluate the safety and efficacy of pembrolizumab in combination with Pfizer’s small molecule kinase inhibitor axitinib (Inlyta) in patients with renal cell carcinoma.  Separately, pembrolizumab plus Pfizer’s PF-05082566 (PF-2566), an investigational immuno-oncology agent that targets the human 4-1BB receptor, will be evaluated in multiple cancer types.  These studies are expected to begin enrollment later this year.

Pembrolizumab (MK-3475) is an investigational, humanised, monoclonal antibody against PD-1 designed to reactivate anti-tumour immunity.  Pembrolizumab exerts dual ligand blockade of the PD-1 pathway by inhibiting the interaction of PD-1 on T cells with its ligands PD-L1 and PD-L2.

Pembrolizumab is currently being evaluated across more than 30 types of cancers, as monotherapy and in combination.  It is anticipated that by the end of 2014, the pembrolizumab development programme will grow to more than 24 clinical trials, enrolling an estimated 6,000 patients at nearly 300 clinical trial sites worldwide.