After the first occurrence of hematologic dose-limiting toxicity in a patient, all subsequent patients receive filgrastim (G-CSF) subcutaneously (SC) beginning 4 days prior to undergoing apheresis and continuing until 6 million CD34+ cells/kg are collected. After 2 patients in a cohort group experience hematologic dose-limiting toxicity, subsequent patients undergo autologous peripheral blood stem cell (PBSC) transplantation.