Purpose: Cyclophosphamide (CPA) has a broad spectrum of activity against solid tumors. Hepatic self-induction of the active metabolite 4-hydroxycyclophosphamide occurs after repeated administration. We evaluated the clinical efficacy of a window regimen that administers fractionated CPA in conjunction with etoposide (VP16) in children with advanced or refractory solid tumors.
Patients and methods: Seventeen children with advanced (n = 12) or refractory (n = 5) solid tumors were entered onto this phase II window study. The treatment regimen consisted of intravenous (IV) CPA 500 mg/m(2)/d and IV VP16 100 mg/m(2)/d. Both drugs were administered daily by short infusions for 5 consecutive days.
Results: A total of 34 courses were administered, with a median of two courses per patient. The median interval between chemotherapy courses was 21 days (range, 17 to 35 days). Thirty-three courses were assessable for toxicity, and all patients were assessable for response. No life-threatening toxicities were observed. The incidence of grade 3 or 4 neutropenia was 94% and of fever and neutropenia 38%. Fever and neutropenia occurred after 12 of 26 courses without recombinant human granulocyte colony-stimulating factor (rhG-CSF) and after one of eight courses with rhG-CSF (P =. 09). Grade 3 or 4 thrombocytopenia occurred after 10 courses (29%). There were no positive blood cultures. One heavily pretreated patient developed a localized perirectal abscess that required drainage. There were 10 patients (59%) with partial responses, four (23.5%) with stable disease, and three with progressive disease.
Conclusion: Fractionated IV CPA and VP16 over 5 days can be safely administered in children with advanced or refractory solid tumors and has notable antineoplastic activity.