High-dose vincristine, fractionated total-body irradiation and cyclophosphamide as conditioning regimen in allogeneic and autologous bone marrow transplantation for childhood acute lymphoblastic leukaemia in second remission: a 7-year Italian multicentre study

We investigated the feasibility and efficacy of high-dose vincristine (4 mg/m² over 4 d) combined with fractionated total body irradiation (F-TBI) (200 cGyx2 over 3 d) and cyclophosphamide (60 mg/kg for 2 d) as a preparative regimen in allogeneic (AlloBMT) and autologous (ABMT) bone marrow transplantation for 75 consecutive children (median age at transplant 8-5 years) with acute lymphoblastic leukaemia in second complete remission (CR). Median duration of first CR was 26 and 25 months in the AlloBMT and ABMT group, respectively. Of the 46 patients who underwent AlloBMT, 33 had isolated or combined marrow relapse and 13 isolated extramedullary relapse. Of the 29 patients given ABMT, 23 had preBMT isolated or combined marrow relapse and six isolated extramedullary relapse. 44/75 patients are alive and in CR at a median follow-up of 35 months (range 10-90 months). Seven children given AlloBMT (15.8%) and two given ABMT (7%) died from transplant-related causes. No major early organ toxicity, including vincristine-related toxicity, was recorded. The overall 3-year EFS estimate (95% CL) was 53.8% (42-66%): in particular, 58.2% (40-76%) for AlloBMT and 27.6% (9-46%) for ABMT patients who experienced a marrow relapse before transplant. The overall 3-year relapse rate estimate (95% CL) was 39.2% (27-51%): in particular, 30.1% (12-49%) in the AlloBMT group and 72% (54-91%) in the ABMT group ( P < 0.01) who presented a preBMT isolated or combined marrow relapse. We conclude that the conditioning regimen with high-dose vincristine combined with cyclophosphamide and F-TBI is feasible and promising, although its therapeutic advantage should be tested in larger series of patients enrolled in randomized studies.