PREDICTIVE FACTORS FOR PERIPHERAL-BLOOD PROGENITOR-CELL COLLECTIONS USING A SINGLE LARGE-VOLUME LEUKAPHERESIS AFTER CYCLOPHOSPHAMIDE AND GRANULOCYTE-MACROPHAGE COLONY-STIMULATING FACTOR MOBILIZATION

Purpose: (1) To study the ability of mobilized peripheral-blood progen itor cells (PBPC) collected in a single targe-volume leukapheresis per formed on a predetermined date to accelerate engraftment after high do se cyclophosphamide and thiotepa; (2) to establish the minimum dose of PBPC associated with early engraftment; and (3) to identify parameter s predictive of collection of large numbers of PBPC. Patients end Meth ods: Twenty-three patients with breast cancer received cyclophosphamid e (4 g/m(2)) and granulocyte-macrophage colony-stimulating factor ([GM -CSF] 5 mu g/kg/d x 15 days) for PBPC mobilization. A single leukapher esis was performed 15 days after cyclophosphamide administration. Then , patients received high-dose cyclophosphamide and thiotepa followed b y reinfusion of PBPC and 4-hydroperoxycyclophosphamide (4HC)-purged bo ne marrow. PBPC concentration was measured in serial peripheral-blood samples and in the leukapheresis product. Correlation analysis between PBPC dose and engraftment and between leukapheresis yield and patient characteristics was attempted. Results: A single leukapheresis proces sed a median 36 L (range, 24 to 46) blood and collected 5 x 10(6) CD34 (+) cells/kg (< 0.3 to 24) and 6.2 x 10(5) colony-forming units granul ocyte-macrophage (CFU-GM)/kg (< 0.001 to 29). All sixteen patients (70 %) reinfused with greater than or equal to 2.9 x 10(6) CD34(+) cells/k g reached a level of greater than 1,000 leukocytes/mu L by day 13 and greater than 50,000 platelets/mu L by day 15. All of these patients ha d a percentage of peripheral-blood CD34(+) cells greater than or equal to 0.5%, and all but one, a level of greater than 100,000 platelets/m u L, on the day of leukapheresis. The bone marrow CD34(+) cell percent age at study entry predicted the number of CD34(+) cells collected aft er PBPC mobilization (R(2) = .42, P = .002). All patients with greater than or equal to 2.5% bone marrow CD34(+) cells experienced early eng raftment. Conclusion: Reinfusion of PBPC collected in ct single leukap heresis accelerates engraftment in the majority of patients. Pretreatm ent bone marrow CD34(+) cell content determines PBPC mobilization capa city and may help select hematopoietic rescue strategies. (C) 1995 by American Society of Clinical Oncology.