OUTLINE: This is a dose escalation study of melphalan. Prior to high dose melphalan and amifostine cytoprotection, patients may receive cyclophosphamide IV. Filgrastim (G-CSF) is given until cytapheresis is completed. Patients receive high dose melphalan according to an escalating dose schedule. High dose melphalan is administered IV on day -1. Amifostine is also administered on days -2 and -1. Peripheral blood stem cell transplantation is performed on day 0. Dose escalation of high dose melphalan continues until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which 2 of 8 patients experience dose limiting toxicity. After the MTD of high dose melphalan is determined, additional patients are treated at this dose level. Patients are followed at days 30, 100, 365, and yearly thereafter.