Combined continuous infusion etoposide with high-dose cyclophosphamide for refractory neuroblastoma: A phase II study from the Société Française d'Oncologie Pédiatrique

Purpose; Patients older than 1 year with stage IV neuroblastoma who fail to achieve complete remission (CRem) have a particularly poor long-term prognosis. In an attempt to improve the outcome of these refractory patients, we tested a new drug combination. Patients and Methods: Twenty-nine children with advanced neuroblastoma (27 stage IV and two stage III) were entered onto this phase II study. All were refractory to conventional chemotherapy and had measurable disease at the time of the trial. The regimen was a combination of high-dose cyclophosphamide (2 g/m²/d) on days 2, 3, and 4, and etoposide (VP16; 50 mg/m²/d) by continuous intravenous (IV) infusion on days 1 to 5. A pharmacokinetic study of VP16 was conducted in eight patients to determine whether the goal of persistent plasma levels between 1 and 5 μg/mL was achieved. Results: Patients received a median of two courses, for a total of 58 courses. The median interval between each course was 32 days. In the 28 assessable patients, the overall response rate was 43%, with one CRem and 11 partial remissions (PRems). No life-threatening complication was observed in these heavily pretreated patients. The median duration of neutropenia ( < 5 × 10⁹/L) was 14 days, and that of thrombocytopenia ( < 50 × 10⁹/L) was 11 days. The overall incidence of sepsis was 27%. Gastrointestinal toxicity was frequent, but mild. Electrolyte disturbance with antidiuretic hormone (ADH)-like syndrome occurred in eight courses, but resolved rapidly. Grade ≥ 2 hemorrhagk cystitis was observed in three courses. No cardiac toxicity was observed. There were no treatment-related deaths. Pharmacokinetic analysis showed that mean steady-state plasma levels (C_as of VP16 were greater than 1 μg/mL during all the courses. Conclusion; This new drug combination appears to be effective in advanced neuroblastoma. Its toxicity remains manageable, with no life-threatening complications. Further evaluation in patients with less-advanced disease is warranted.