Cladribine and Rituximab in Treating Patients With Hairy Cell Leukemia

This phase II trial studies the side effects and how well cladribine and rituximab work in treating patients with hairy cell leukemia. Drugs used in chemotherapy, such as cladribine, 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. Immunotherapy with monoclonal antibodies, such as rituximab, may help the body's immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread. Giving cladribine together with rituximab may kill more cancer cells.