PD-1 Blockade with the Monoclonal Antibody Pembrolizumab (MK-3475) in Patients with Classical Hodgkin Lymphoma after Brentuximab Vedotin Failure: Preliminary Results from a Phase 1b Study (KEYNOTE-013)

The programmed death-1 (PD-1) pathway serves as an immune checkpoint to temporarily dampen immune responses upon chronic antigen stimulation. Normal antigen presenting cells and certain tumor cells express the PD-1 ligands, PD-L1 and PD-L2, which engage PD-1 receptors on activated T cells and induce T-cell exhaustion. PD-1 signaling is a potent mechanism of tumor immune escape and a compelling target for therapy. Antibody-mediated PD-1 blockade...