COURSE Va (allogeneic PBSCT for patients with human leukocyte antigen [HLA]-matched sibling donor): Beginning 3-10 days after completion of course IV, patients with an HLA-matched sibling donor undergo total body irradiation (TBI) 2-3 times daily on days -7 to -4. Patients receive etoposide IV over 4 hours on day -3. Patients then undergo PBSCT on day 0. Patients then receive graft-vs-host disease prophylaxis with tacrolimus IV continuously on days -1 to 56 (or IV continuously on days -1 to 14 and then PO or IV every 12 hours on days 15-56) followed by a taper. Patients also receive methotrexate IV on days 1, 3, and 6, and filgrastim subcutaneously (SC) beginning on day 4 and continuing until blood counts recover.