Acute reactions will be managed using standard therapy for acute drug reac tions as per institu tional standard of care and reported to the sponsor. 4.1.3 Pembrolizumab (KEYTRUDA®, MK-3475) is a potent and highly-selective humanized monoclonal antibody (mAb) of the IgG4/kappa isotype designed to directly block the interaction betw een PD-1 and its ligands, PD-L1 and PD- L2. It is FDA-approved for treating me tastatic melanoma and metastatic PDL1 positive non-small cell lung cancer. Pembrolizumab will be administered IV over 30 minutes at 200 mg. Antiemetic medications should not be routinely administered prior to dosing except as indicated by patient’s prior reaction.