Mobilization of peripheral blood stem cells in CLL patients after front-line fludarabine treatment

Autologous peripheral blood stem cell transplantation is performed in an increasing number of chronic lymphocytic leukaemia (CLL) patients who are in the first remission following fludarabine treatment. There are contradictory data about the adverse impact of fludarabine on stem cell harvest. We analysed retrospectively mobilization results in 56 poor-risk CLL patients (median age: 56 years) who underwent first-line treatment with fludarabine and cyclophosphamide. The mobilization, consisting of cyclophosphamide 3 g/m² and granulocyte colony-stimulating factor (G-CSF) 10 μg/kg per day, was performed with a median of 77 days following the last fludarabine course. The target yield was ≥2.0×10⁶ CD34+ cells/kg. The procedure was successful in 23 (41%) patients. A median of 3.3×10⁶ CD34+ cells/kg was collected per patient. The successful mobilization was associated with a longer interval from the last chemotherapy (>2 months). The mobilization result was not influenced by the number of fludarabine cycles. No correlation was found in other parameters such as disease stage at diagnosis, disease status at stimulation or age. The poorly mobilized patients had significantly lower prestimulation blood counts (platelets, WBC and haemoglobin). Our data show that fludarabine does not generally prevent the stem cell mobilization; nevertheless, mechanisms related to the impact of fludarabine on stem cell harvest must be further investigated.