sentence: Paclitaxel and vinorelbine are among the most active new agents in metastatic breast cancer .
paragraph: Phase I/II study of paclitaxel and vinorelbine in metastatic breast cancer.  Paclitaxel and vinorelbine are among the most active new agents in metastatic breast cancer . Both in vitro and in vivo studies have shown that the combined administration of these two microtubule-targeting agents is feasible and worthwhile. Based on the promising preclinical data, patients with metastatic breast cancer no longer amenable to conventional treatment were entered into a phase I/II study in which the vinorelbine dose was fixed at 30 mg/sqm and paclitaxel was started at 90 mg/sqm and then subsequently escalated by 30 mg/sqm per step. Cycles were repeated every 21 days. Hematopoietic growth factor support was provided from the 4th dose level onwards. Grade III neutropenia was observed only in 2 patients treated at the 5th dose level. Thrombocytopenia never reached grade 3. Neurotoxicity was considered dose-limiting, since grade 3 peripheral neuropathy occurred in all three patients treated at the 6th dose level. Other toxicities were mild. paclitaxel 210 mg/sqm and vinorelbine 30 mg/sqm was the selected combination for phase II. Overall response rate in 34 evaluable patients was 38% (95% confidence interval (C.I.), 22% to 54%). In particular, 3 complete responses (9%) and 10 partial responses (29%) were observed. The observed level of antitumor activity, with an overall response rate of 38% and a median duration of response of 12 months, is of interest, since the study was targeted only to anthracycline-pretreated patients, most of whom had adverse prognostic features. The evaluation of a combination of vinorelbine and paclitaxel as first-line therapy in metastatic breast cancer seems worthwhile and is currently undergoing.