Summary:In the present study the in vitro growth of CFU-GM from PBPC of patients with AML (n = 11), purged with mafosfamide alone or a combination of mafosfamide and amifostine, was compared to historical controls of mafosfamide-purged bone marrow (AML CR1, n = 16). Two patients were transplanted with mafosfamide and mafosfamide/amifostine pretreated PBPC autografts. The in vitro experiments demonstrated a significantly higher resistance of peripheral blood derived CFU-GM to mafosfamide (median ID 95 190 g mafosfamide/ml) compared with bone marrow derived CFU-GM (median ID 95 130 g/ml). Preincubation with amifostine significantly further increased the median ID 95 to 245 g/ml. The clinical results showed short recovery times for neutrophils Ͼ500/ l (9 and 13 days) and platelets Ͼ20 000/ l (12 and 21 days) and stable long-term engraftment with one relapse at day ؉118 and one patient in CR at day 760 after transplantation. The in vitro results show a significant advantage of PBPC over bone marrow-derived progenitors for purging with mafosfamide. Furthermore, a protective effect from mafosfamide of amifostine on normal progenitors could be demonstrated. The clinical results demonstrate the clinical feasibility of using mafosfamide-purged autologous PBPCT without impairing the short-term and longterm repopulating capacities of the autografts. Bone Marrow Transplantation (2000) 25, 831-836.

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