Granulocyte colony-stimulating factor given in addition to interferon-α to mobilize peripheral blood stem cells for autologous transplantation in chronic myeloid leukaemia

In order to potentially mobilize and harvest the Ph^? cells observed in most patients with chronic myeloid leukaemia (CML) during interferon-α (IF-α) therapy, G-CSF (filgrastim), 5 μg/kg/d, was administered subcutaneously together with IF-α to 30 CML patients in haematological remission but with various degrees of cytogenetic remission, after IF-α therapy. Peripheral blood stem cells (PBSC ) were harvested using standard aphereses from day 5 of G-CSF. Patients underwent one to four (median three) aphereses. Median total yields/kg were 7.6 (range 3.8–25) × 10⁸ MNC, 3.4 (0–140) × 10⁶ CD34⁺ cells, and 17 (1.1–107) × 10⁴ CFU-GM. No patient had a significant increase in the percentage of Ph⁺ cells in the bone marrow under G-CSF therapy. The percentage of Ph⁺ cells in apheresis products tended to decrease between the first and the last apheresis (P = 0.05). 14 patients who were not responsive to IF-α were transplanted after conditioning with busulphan 16 mg/kg and melphalan 140 mg/m². Median time to neutrophils > 0.5 × 10⁹/l was 20 d (16–114 d) and to platelets > 50 × 10⁹/l 18 d (12–149 d). Nine patients had a major cytogenetic response post graft, which correlated with the amount of Ph⁺ cells reinfused with the graft (P = 0.02). We conclude that this procedure is feasible, allowing the harvest of enough PBSC, some of them Ph^? in patients who responded to IF-α, to allow autologous transplantation.