Purpose

This phase III trial studies ibrutinib and rituximab to see how well they work compared to fludarabine phosphate, cyclophosphamide, and rituximab in treating patients with untreated chronic lymphocytic leukemia or small lymphocytic lymphoma. Ibrutinib may stop the growth of cancer cells by blocking some of the enzymes needed for cell growth. Chemotherapy drugs, such as fludarabine phosphate and cyclophosphamide, work in different ways to stop the growth of cancer cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Rituximab is a monoclonal antibody. It binds to a protein called CD20, which is found on B cells (a type of white blood cell) and some types of cancer cells. This may help the immune system kill cancer cells. It is not yet known whether fludarabine phosphate, cyclophosphamide, and rituximab may work better than ibrutinib and rituximab in treating patients with untreated chronic lymphocytic leukemia or small lymphocytic lymphoma.