CCR4 and esophageal cancer: Immune checkpoint inhibitors used in studies of esophageal cancer are the following: Nivolumab an anti-PD-1 antibody is being tested in a phase II trial for patients with advanced esophageal cancers; Pembrolizumab is also being tested; MPDL3280A, an anti-PD-L1 antibody is being tested; Urelumab and PF-05082566 an anti-4-1BB/ CD137 antibody is being tested; Mogamulizumab, an anti-CCR4 antibody, is being developed in a phase I trial for patients with advanced solid tumors.