Patients receive oral busulfan every 6 hours on days -8 to -6 followed by melphalan IV over 30 minutes on days -5 and -4 and thiotepa IV over 2 hours on days -3 and -2. Patients receive amifostine IV over 5 minutes beginning 30 minutes prior to melphalan and thiotepa administration on days -5 to -1. PBSC are reinfused on day 0.