BACKGROUND.
Vinorelbine given by weekly bolus injection is active and less toxic than bolus vinblastine in the treatment of patients with metastatic breast carcinoma. Vinblastine given by 5-day continuous infusion showed a steep doseresponse curve. Pharmacokinetic studies of vinorelbine showed that it is possible to achieve a comparable antitumor effect with a smaller amount of the drug if it is given by continuous infusion. The purpose of this study was to determine the efficacy of vinorelbine given by 96-hour continuous infusion to patients with refractory metastatic breast carcinoma patients.
METHODS.
Between May 1996 and August 1997, 47 patients with metastatic breast carcinoma were registered into the study. All patients previously had received doxorubicin and 70% had undergone prior paclitaxel treatment. Approximately 56% of the patients had ี2 metastatic sites. All patients received vinorelbine according to the following dose schedule: 8 mg bolus followed by 11 mg/m 2 by continuous infusion over 24 hours every 4 days every 3 weeks.
RESULTS.
Forty-four patients were evaluable for response. A total of 193 cycles were administered. The overall response rate was 16% (2 patients achieved a complete response and 5 patients achieved a partial response). The median duration of response was 4.3 months and the median overall survival was 8.6 months.
Patients with visceral metastases and/or multiple sites of involvement had shorter durations of response than patients with only soft tissue disease or single-site metastasis (3.1 months vs. 4.9 months) and shorter overall survival (8.1 months vs. 12 months). Dose reductions were necessary due to cumulative stomatitis and/or fatigue in 12 cycles and neutropenia and/or infection in 13 cycles.
CONCLUSIONS.
Due to toxicity, a revised maximum tolerated dose for continuous infusion vinorelbine is proposed by the authors: 8 mg intravenously over 10 minutes followed by 10 mg/m 2 by continuous infusion over 24 hours every 4 days.
The current dose schedule did not offer an advantage either in response rates or survival over the weekly vinorelbine bolus injection in doxorubicin-resistant and paclitaxel-resistant patients.