A Phase II Study of Carfilzomib in Relapsed Waldenström's Macroglobulinemia (WM) IST-CAR-531

The purpose of this study is to evaluate the safety and effectiveness of an investigational study drug called carfilzomib. The investigators want to find out what effects, good and/or bad, it has on patients and their cancer if treatment continues beyond previous carfilzomib treatment study. Carfilzomib (KyprolisTM) is approved by the U.S. Food and Drug Administration (FDA) to be used only in certain U.S. patients with relapsed and refractory multiple myeloma that have tried and failed other therapies. It has not been approved to be used for any other disease or condition. In this study, carfilzomib is referred to as an investigational study drug because it is not approved for use in all patients with multiple myeloma in the United States, and it is not approved by some regulatory authorities (the agencies that are responsible for approving the use of a medicine in a country such as Health Canada). Carfilzomib is a type of drug called a proteasome inhibitor. A proteasome is a protein found within cells that has the important role of identifying and marking damaged proteins that are needed to be destroyed by the cell for survival. The inhibition of the proteasome allows for damaged protein to accumulate within cells. This accumulation of damaged protein causes the cell to die.