<qa>  What is the name of the drug that can be used to deliver the donated stem cells?Participants will have a central venous line large plastic tube placed into a major vein. This tube can stay in the body and be used during the entire treatment period to deliver the donated stem cells and give medications, including chemotherapy and other drugs, antibiotics and blood transfusions, and to withdraw blood samples. Treatment will start with induction chemotherapy, which will include the drugs fludarabine, cyclophosphamide, etoposide, doxorubicin, vincristine, and prednisone. Some patients may also receive an antibody called rituximab. Patients will receive one to three cycles of this treatment, depending on their response to the drugs. One cycle consists of 5 days on drug therapy followed by a 16-day rest period. Several days before the transplant procedure, patients will start conditioning chemotherapy with cyclophosphamide and fludarabine. Three days after the conditioning therapy is completed, the stem cells will be infused. To help prevent GVHD, patients will take four doses of methotrexate by vein shortly after the transplant, and cyclosporine by mouth or by vein for about 6 months after the transplant. 