<qa>  What is the name of the immunotherapy drug used in chemotherapy?RATIONALE: Drugs used in chemotherapy use different ways to stop cancer cells from dividing so they stop growing or die. Monoclonal antibodies such as rituximab can locate cancer cells and either kill them or deliver cancer-killing substances to them without harming normal cells. It is not yet known if combination chemotherapy is more effective with or without rituximab in treating mantle cell lymphoma. 