A Study of Daratumumab in Patients With Relapsed or Refractory Waldenström Macroglobulinemia

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 Daratumumab for this specific disease but it has been approved for other uses. Daratumumab is a monoclonal human antibody. An antibody recognizes a specific protein and binds to it. Daratumumab binds to a protein called CD38 located on the surface of B cells like WM. Daratumumab has shown the ability to slow or stop the growth of cells that have CD38 on the cell surface when tested in laboratories. In this research study, the investigators are evaluating the efficacy of Daratumumab as a single agent in participants with WM that has come back or has shown no response to previous treatment.