Weekly paclitaxel in metastatic breast cancer patients: a phase II study

AIMS ANID BACKGROUND: Paclitaxel, a microtubule inhibitor, is one of the most active drugs in metastatic breast cancer. A weekly schedule, at a median dose-intensity of 91 mg/m2, is effective and has less side effects than a 3-week schedule. In this phase II study, we evaluated the toxicity and the activity of weekly 1 hr paclitaxel infusions in metastatic breast cancer patients.

Between February 1999 and February 2001, 26 patients with metastatic breast cancer were treated with weekly paclitaxel (60-90 mg/m2/1 hour iv infusion/weekly). The treatment was planned to continue until disease progression or prohibitive toxicity; in patients with responsive or stable disease, paclitaxel was stopped after 6 months of therapy.

At a median follow-up of 18.7 months (range, 6.8-30.8), all patients are assessable for response and toxicity. We obtained 8 partial responses (30.8%), 8 stable disease (30.8%) and 10 disease progression (38.4.%). The overall response was 30.8% (95% CI, 13.1-48.5). The median duration of response was 7.6 months (range, 1.8-12.4); median time to progression was 4.86 months (range, 1.4-12.4); median overall survival was 9.9 months (range, 1.7-29.2+). Treatment was well tolerated. Hematological toxicity was mild and only one patient developed grade 3 anemia. Two patients experienced grade 3 cardiovascular toxicity; both had received anthracycline-based regimens.

In our experience, weekly administration of paclitaxel shows a substantial degree of activity even in pretreated metastatic breast cancer patients. The toxicity profile is favorable.