Early total white blood cell recovery is a predictor of low number of apheresis and good CD34+ cell yield

Objective. We analysed peripheral blood progenitor cell (PBPC) mobilisation and collection in order to assess the main factors related to CD34⁺ cell yields in patients affected by haematological malignancies.

Patients and Methods. The features of CD34⁺ cell mobilisation of patients with haematological malignancies that underwent autologous bone marrow transplantation were examined. Mobilisation chemotherapy consisted mainly of cyclophosphamide (CY) 4 or 7 g/m² followed by growth factors. Leukapheresis was started when the WBC counts reached 1.0 × 10⁹/l with the aim to collect at least 5 × 10⁶ CD34⁺ cells/kg body weight. The aphereses were performed on continuous-flow blood cell separators. The analysed variables were: age, diagnosis, CT mobilisation regimen, type of growth factor, number of previous CT lines, prior radiotherapy, days for WBC recovery and number of aphereses procedures to achieve the target of CD34⁺ cells.

Results. There were 41 consecutive patients (26 M/15 F): 21 non-Hodgkin’s lymphoma (NHL), 15 Hodgkin’s disease (HD), two chronic myeloid leukaemia (CML) and three multiple myeloma (MM). Eleven patients could not collect the proposed threshold of CD34⁺ cells. CY 4 mobilised patients recovered WBC counts in less days (P=0.03). By ANOVA, the days to WBC recovery had a linear function of the predictors “number of aphereses” and “type of mobilisation CT” (coefficients: 0.86 and 0.95, respectively). For the number of aphereses and WBC recovery after CT mobilisation, we obtained a correlation coefficient of 0.36 (P=0.02).

Conclusion. This study shows that it is feasible to mobilise and collect PBPC in patients previously treated with CT with or without RT. There was a linear correlation between the days for WBC recovery and the number of aphereses needed to collect the target number of CD34⁺ cells. The study suggests that early WBC recovery, using mainly CY 4 mobilisation chemotherapy, is an important predictor of a low number of aphereses to achieve a good CD34⁺ yield.