Peripheral blood progenitor cell (PBPC) counts during steady-state haemopoiesis enable the estimation of the yield of mobilized PBPC after granulocyte colony-stimulating factor supported cytotoxic chemotherapy: an update on 100 patients

Peripheral blood progenitor cells (PBPC) can be mobilized using chemotherapy and granulocyte colony-stimulating factor (G-CSF). We and others previously reported a correlation of steady-state PBPC counts and the PBPC yield during mobilization in a small group of patients, Here we present data on 100 patients (patients: 25 non-Hodgkin's lymphoma (NHL), Eve Hodgkin's disease, 35 multiple myeloma (MM), 35 solid tumour) which enabled a detailed analysis of determinants of steady-state PBPC levels and of mobilization efficiency in patient subgroups, Previous irradiation (P=0.0034) or previous chemotherapy in patients with haematological malignancies (P=0.0062) led to a depletion of steady-state PB CD34(+) cells. A correlation analysis showed steady-state PB CD34(+) cells (all patients: r=0.52, P<0.0001, NHL patients, r=0.69, P=0.0003; MM patients: r=0.66, P=0.0001) and PB colony-forming cells can reliably assess the CD34(+) cell yield in mobilized PB. In patients with solid tumour a similar trend was observed in mobilization after the first chemotherapy cycle (r=0.51, P=0.05) but not if mobilization occurred after the second or further cycle of a sequential dose-intensified G-CSF-supported chemotherapy regimen, when premobilization CD34(+) counts were 18-fold elevated (P=0.004). When the patients with MM (r=0.63, P=0.0008) or with NHL (r=0.65, P=0.006) were analysed separately, a highly significant correlation of the steady-state PB CD34(+) cell count to the mean leukapheresis CD34(+) cell yield was found, whereas no correlation was observed for patients with a solid tumour. For patients with haematological malignancies estimates could be calculated which, at a specific steady-state PB CD34(+) cell count, could predict with a 95% probability a defined minimum progenitor cell yield, These results enable recognition of patients who mobilize PBPC poorly and may assist selection of patients for novel mobilization regimens.