If a partial response is seen with modified R-Hyper-CVAD, you will have some of your stem cells collected. You will receive 1 cycle of cladribine, cyclophosphamide, and rituximab. Cladribine will be given through a vein once a day over 2 hours on Days 1-5. Cyclophosphamide is taken by mouth, twice a day on Days 1-5, and rituximab is given through a vein once a week for 4 weeks.