Background: An intravenous form of busulfan has been developed to replace oral busulfan in conditioning treatment prior to haematopoietic stem cell transplantation (HSCT).
Aim: Retrospective evaluation of the efficacy and safety of iv busulfan in paediatric patients.
Methods: A total number of 33 patients entered the study: 11 patients received intravenous Bu-based conditioning before HSCT (group A; 3 allo, 8 auto); 22 patients received oral Bu-based conditioning (group B; 5 allo, 17 auto). The median age was 5.3 (1.5-20) years. An intravenous dosing of busulfan based on body weight was used. Patients were conditioned with BuCy+/-Vp+/-ATG or BuMel protocols. Cyclosporin+/-methotrexate were used for GVHD prophylaxis during allo-HSCT.
Results: Patients in group A were younger (p=0.005), received comparable amount of MNC and CD34 cells. The median time of neutrophil engraftment was similar in both groups: 12 (10-19) vs 12.5 (10-25) days, while platelet recovery was shorter in group A: 11.5 (7-30) vs 14 (9-187) days (p=0.019). Severe stomatitis occurred in 5/11 patients in group A and in 19/22 patients in group B (p=0.033). Additional analgesics were required, respectively, by 5/11 and 17/22 patients (p=0.117). There were no significant differences in a/cGVHD, gastrointestinal reaction, hepatic toxicity, occurrence of infections and haemorrhagic cystitis between the two groups. With a median follow-up of 9 months in group A and 12 months in group B, 8 (72.7%) patients in group A and 15 (68,2%) patients in group B were alive. 9/10 deaths were related to disease relapse. With this short follow up, the probability of relapse and overall survival were comparable in both groups.
Conclusions: The intravenous Bu-based conditioning treatment before HSCT for paediatric patients has a favorable toxicity profile. It has the potential to accelerate haematological reconstitution and to improve survival and engraftment in children undergoing HSCT. The i.v. administration is convenient, favouring its more widespread application. Further studies are needed.