INTRODUCTION: The programmed death-1 (PD-1) immune checkpoint pathway is an 
emerging target in the treatment of hematologic malignancies. Pidilizumab is an 
mAb that binds to PD-1 and is a safe and well-tolerated therapy. Recent data 
have shown clinical activity utilizing this strategy in diffuse large B-cell 
lymphoma (DLBCL).
AREAS COVERED: The role of PD-1 expression in hematologic malignancies is 
explored. Recent clinical trials including the results of a Phase I trial in 
hematologic malignancies and a Phase II trial of pidilizumab following 
autologous hematopoietic stem-cell transplant (AHSCT) are reviewed.
EXPERT OPINION: We review data that suggest that PD-1 is a promising target in 
the treatment and management of DLBCL. Changes in immune subsets following 
administration of pidilizumab are felt to represent on-target responses. The 
improvement in progression-free survival (PFS) following AHSCT supports a 
response to therapy. Importantly, the improvement in PFS for patients with 
positive FDG-PET/CT following AHSCT indicating residual disease further supports 
direct activity of pidilizumab in DLBCL.