Optimization of the yield of PBSC for autotransplantation mobilized by high-dose chemotherapy and G-CSF: Proposal for a mathematical model

We analyzed the results of 71 leukapheresis procedures performed in 21 patients to identify the best predictive factors affecting the yield of peripheral blood progenitors after high-dose chemotherapy followed by G-CSF administration. An average of 1 ± 1 x 10⁸ MNC/kg, 5 ± 6 x 10⁴ CFU-GM/kg and 4 ± 6 x 10⁶ CD34+ cells/kg was collected for each leukapheresis. When we defined ≥ 5 x 10⁴/kg as the minimum number of CFU-GM per procedure for a 'satisfactory' collection, multiparameter analysis of clinical features and laboratory findings showed that the only factors that predicted the numbers of CFU-GM collected were prior treatment with the MOPP regimen and the number of mononuclear cells identified in the basophil channel of the H*1=Technicon. A logistic regression analysis performed to generate a mathematical model revealed four predictive factors: the number of previous cycles of chemotherapy, previous MOPP chemotherapy, the interval from latest chemotherapy and the number of mononuclear cells/μl. This model was valuable in defining the optimal time for the first leukapheresis procedure. In contrast, the number of circulating CD34+ cells did not correlate with CFU-GM numbers collected whereas the numbers of mononuclear cells did provide a simple and reliable index. Thus the principal factor affecting the efficiency of peripheral blood stem cell collection was prior therapy with MOPP.