Infusional paclitaxel and weekly vinorelbine chemotherapy with concurrent filgrastim for metastatic breast cancer: High complete response rate in a phase I-II study of doxorubicin-treated patients

Purpose: We investigated 96-hour paclitaxel infusion combined with weekly (days eight and 15) vinorelbine as salvage therapy for metastatic breast cancer in anthracycline-exposed patients. All patients received scheduled support with granulocyte colony-stimulating factor (G-CSF; filgrastim). Tumor response, toxicity, time to progression (TIP), and survival were assessed. Patients and Methods: This single-center nonrandomized trial enrolled 32 patients. Anthracycline exposure and subsequent progression were common to all patients. Paclitaxel and vinorelbine were escalated over three dosing levels, stratified by liver function. Results: Seven patients (22%) achieved a complete response and nine patients achieved a partial response for an overall response rate of 50%. The median TTP was 6.1 months, and median survival time was 14.1 months. Dose- limiting toxicity was neutropenia, with dose delay or reduction in seven of 32 patients. Febrile neutropenia requiring hospitalization was uncommon (three of 32 patients; 9%). There were no treatment-related deaths. Grade 3/4 thrombocytopenia occurred in two patients (6%), and 13 patients (41%) required RBC transfusions for anemia. Grade 3 nausea and vomiting was seen in one patient, who was found to be Addisonian. Despite potentially overlapping neurologic toxicities of the two agents, only two patients (6%) were removed from the study because of progressive peripheral neuropathy. Conclusion: Administration of 96-hour paclitaxel infusion and subsequent weekly vinorelbine with G-CSF support is well tolerated. The response rate, TTP, and survival data are encouraging for therapy given to anthracycline pretreated patients with metastatic breast cancer. If these results can be verified in multi-institution trials, this or a similar combination of drugs would merit investigation as first-line therapy in this patient population.