Pilot Study of Pembrolizumab Treatment for Disease Relapse After Allogeneic Stem Cell Transplantation

This pilot study has been designed to investigate the safety of pembrolizumab treatment for disease relapse following allogeneic stem cell transplant (alloSCT). Pembrolizumab will be administered at a fixed dose of 200 mg IV every 3 weeks. Approximately 12-26 patients with relapsed MDS, AML, or mature B cell (B-NHL, cHL) malignancies that have relapsed following alloSCT will be enrolled on this trial. Pembrolizumab treatment will be administered for up to 24 months, provided that neither disease progression, nor development of a dose-limiting toxicity (DLT), has occurred. Adverse events will be monitored every three weeks throughout the trial and graded in severity according to the guidelines outlined in the NCI Common Terminology Criteria for Adverse Events (CTCAE) version 4.0. This trial will be conducted in accordance with Good Clinical Practices.