High-dose busulfan/melphalan as conditioning for autologous PBPC transplantation in pediatric patients with solid tumors

Abstract

We conducted a prospective pilot study to assess the feasibility and safety of high-dose busulfan/melphalan as conditioning therapy prior to autologous PBPC transplantation in pediatric patients with high-risk solid tumors. From January 1995 to January 1999, 30 patients aged 2–21 years (median 8) were entered into the study. There were 14 females and 16 males. Diagnoses included neuroblastoma in 10 patients; Ewing’s sarcoma and peripheral neuroectodermal tumor (PNET) in 15 patients and rhabdomyosarcoma in five patients. Treatment consisted of busulfan 16 mg/kg, orally over 4 days (from days −5 to −2) in 6 hourly divided doses, and melphalan at a dose of 140 mg/m² given by intravenous infusion over 5 min on day −1. G-CSF mobilized PBPC were used as autologous stem-cell rescue. One patient developed a single generalized convulsion during busulfan therapy. The most relevant non-hematologic toxicity was gastrointestinal, manifesting as grade 2–3 mucositis and diarrhea in 12 patients. Two patients died of procedure-related complications, one from veno-occlusive disease of liver and multiorgan failure and the other from adult respiratory distress syndrome. Probability of treatment-related mortality was 6.6 ± 4.5%. With a median follow-up of 18 months (range, 1–48), 19 patients are alive and disease-free, the actuarial EFS at 4 years being 55 ± 12% for the whole group. We conclude that high-dose busulfan/melphalan for autologous transplantation in children with solid tumors is feasible even in small patients. It is well-tolerated, with an acceptable transplant-related mortality and has proven antitumor activity.