PDCD1 and B-cell chronic lymphocytic leukemia: Pre-clinical data have demonstrated synergy [58] with dual inhibition and a clinical trial (NCT02420912) involving relapsed, refractory or high-risk treatment-naive patients with CLL and the combination of ibrutinib and nivolumab (humanized IgG4 anti-PD-1 monoclonal antibody) is currently recruiting.