Pembrolizumab in Neoplasms or Lymphomas

This research study is a Phase II clinical trial. Phase II clinical trials test the safety and effectiveness of an investigational drug to learn whether the drug works in treating a specific disease. "Investigational" means that the drug is being studied. The FDA (the U.S. Food and Drug Administration) has not approved pembrolizumab for this specific disease but it has been approved for other uses. The study drug is an antibody that targets a molecule called programmed cell death protein 1 (PD-1). PD-1 is used to turn down the immune system. In general, this is used by the body to prevent the immune system from being too active. However, several cancers appear to use this pathway to prevent the immune system from attacking them. The theory behind this study is that by blocking PD-1, we may be able to prevent the cancer from hiding from the immune system and allow the immune system to attack the cancer more effectively. There is evidence that the type of lymphoma the participant have may use PD-1 to escape the immune system.