Objective: The aim of this study was to evaluate topotecan with carboplatin in an alternating doublet with carboplatin and paclitaxel in first-line ovarian cancer.
Methods: Patients with newly diagnosed stage III/IV ovarian cancer were studied. The maximum tolerated dose (MTD) of topotecan (cycles 1, 3, 5, 7) in an alternating doublet regimen was determined through standard dose escalation in cohorts of three; doses of carboplatin (area under the curve [AUC] 4 to 5) and paclitaxel (175 mg/m(2), cycles 2, 4, 6, 8) were fixed. Dose-limiting toxicity (DLT) was defined only for cycle 1 as febrile neutropenia, prolonged grade 4 granulocytopenia, grade 4 thrombocytopenia, > or =grade 3 nonhematologic toxicity, or failure to recover in < or =7 days. The use of granulocyte colony-stimulating factor (G-CSF) to permit further dose escalation was also studied.
Results: Thirty-seven patients received 142 cycles of topotecan/carboplatin. Hematologic DLTs included grade 4 neutropenia (59 events, 42% of cycles) and thrombocytopenia (32 events, 23% of cycles). Granulocytopenia was generally short-lived, and only 2 cases of febrile neutropenia occurred. The MTD was 1.0 mg/m(2)/day topotecan and carboplatin AUC 4, alternating with 175 mg/m(2) paclitaxel and carboplatin AUC 4. Although G-CSF effectively managed myelosuppression, thrombocytopenia developed in later cycles, limiting further topotecan dose escalation. The median progression-free survival was 20.5 months, and elevated pretreatment CA-125 levels normalized in 29 of 34 (85%) patients.
Conclusion: The establishment of a reasonably well-tolerated alternating doublet regimen, coupled with evidence of antitumor activity, provides the basis for further investigation of topotecan in first-line therapy of ovarian cancer. Topotecan (1.0 mg/m(2) daily for 3 days) was chosen for further evaluation in a phase II study.