Mobilization of predominantly Philadelphia chromosome-negative blood progenitors using cyclophosphamide and rHUG-CSF in early chronic-phase chronic myeloid leukaemia: Correlation with Sokal prognostic index and haematological control

Mobilization of Philadelphia chromosome (Ph) negative blood progenitors was attempted in 23 newly diagnosed chronic myeloid leukaemia (CML) patients using a regimen of cyclophosphamide (CY) 5 g/m² and rHUG-CSF 150 μg/m² daily. This regimen was well tolerated with no major adverse events reported. More than 2x 10⁶/kg CD34⁺ cells were collected in 21 patients (91%). Predominantly Ph-negative mobilization (0-25% Ph-positive) was seen in 30% of cases overall and was confined to patients with a Sokal prognostic score < 1 (7/11 with Sokal score <1; 0/12 with Sokal score ≤1). Within the low Sokal index group, a low WBC count pre-mobilization and a low WBC nadir both correlated strongly with Ph-negative mobilization (P = 0.006 and 0.02 respectively). Five of 19 patients receiving at least 6 months of Roferon A therapy post mobilization achieved a major cytogenetic response: all five patients were Ph-negative mobilizers. Therefore CML patients can be divided into a good-prognosis group in whom predominantly Ph-negative progenitors can be mobilized using a regimen of moderate intensity if haematological control is achieved premobilization, and a poor-prognosis group for whom predominantly Ph-positive cells are mobilized with this regimen regardless of haematological control.