Trial of Pembrolizumab in Cancer of Unknown Primary

"Pembrolizumab has high affinity and potent receptor blocking activity for PD-1, based on preclinical in vitro data. Pembrolizumab has an acceptable preclinical and clinical safety profile and is in clinical development as an IV immunotherapy for advanced malignancies.~The PD-1 pathway represents a major immune control switch, which may be engaged by tumour cells to overcome active T-cell immune surveillance. Pembrolizumab is a potent and highly selective humanized mAb of the Immunoglobulin (IgG4)/kappa isotype designed to directly block the interaction between PD-1 and its ligands, PD-L1 and PD-L2. This blockade enhances functional activity of the target lymphocytes to facilitate tumor regression and ultimately immune rejection."