Blood stem cell collections in multiple myeloma: Definition of a scoring system

The purpose of the study was to identify factors that could predict good yields of peripheral blood stem cells (PBSC) in multiple myeloma (MM). Fifty-one MM patients, nine with refractory disease and 42 in plateau phase, were mobilized with high-dose cyclophosphamide (HD-Cy) at 4 g/m² followed by granulocyte colony-stimulating factor (G-CSF) 5 μg/kg/day. Clinical and laboratory parameters at the time of mobilization were analyzed for correlations with the number of CD34⁺ cells collected, with the colony-forming unit granulocyte-macrophage (CFU-GM) count, and the mononuclear cell (MNC) count. In univariate analysis, low WBC count, low platelet count, prior exposure to melphalan, and an interval > 6 months from the start of treatment correlated with poor yields of CD34⁺ cells. Low platelet count, prior exposure to melphalan or to radiotherapy, and an interval > 6 months from the start of treatment were associated with a low CFU-GM count. On the basis of these data, we defined a scoring system able to predict the yield of the mobilizing procedure. According to this system, the presence of more than one risk factor (low WBC and platelet counts, prior exposure to melphalan, interval from first chemotherapy > 6 months) was predictive of insufficient collections when a conventional combination of mobilizing measures are used.