Increasing dose of continuous infusion ifosfamide and fixed dose of bolus epirubicin in soft tissue sarcomas. A study of the Italian group on rare tumors

Purpose: To evaluate the maximum tolerated doses (MTD) of ifosfamide when given as a continuous infusion and in combination with fixed doses of bolus 4'-epidoxorubicin in advanced previously untreated adult soft tissue sarcoma patients, Methods: Treatment consisted of epidoxorubicin, 60 mg/m(2) days one and two, and ifosfamide, 1.5 g/m(2) every 12 hrs as a 72-hr infusion, at the first level, Further levels of ifosfamide were defined as increments of 12 hrs of the same infusion program, G-CSF 300 mu g/die was administered from days +7 to +14, Dose-limiting toxicity (DLT) was defined as: G4 leukopenia or thrombocytopenia of greater than or equal to 5 days; any G3 neuro or nephrotoxicity; G4 toxicity of any kind, Patients had to complete at least 2 consecutive cycles, and MTD was defined as the level in which 20% of patients developed a DLT; 10-15 patients were entered in each level. Results: First level: overall, 13 patients entered, 3 were not assessable for MTD, and only one developed a DLT. Second level: 18 patients entered, 3 were not assessable for MTD, Hematologic DLT was observed in 3/15 assessable patients. Therefore, the MTD was found at the ifosfamide level of 10.5 g/m(2) given in 84 hrs, Eight patients of 29 assessable for response achieved an objective response: 1 complete and 7 partial. The overall response rate was 28% (95% CI: 13-47%), Conclusions: If we accept 4-day G4 leukopenia as a reliable cutoff for safety, ifosfamide intensification cannot be substantially exploited over already available schedules with the combination of ifosfamide and anthracyclines.