Dose-dense therapy with weekly 1-hour paclitaxel infusions in the treatment of metastatic breast cancer

Purpose: To evaluate the efficacy and toxicity of paclitaxel administered as a 1 -hour infusion on weekly basis, without interruption, to patients with metastatic breast cancer who had received prior therapy. Patients and Methods: Thirty patients with metastatic breast cancer received sustained weekly paclitaxel therapy at an initial dose of 100 mg/m² until disease progression. Prior therapy included adjuvant only (n = 17), metastatic only (n = 7), or both (n = 6). Eighteen patients had received prior anthracycline therapy, 12 of whom had demonstrated progression of disease within 12 months of it. All patients were assessable for efficacy; 29 patients were assessable far toxicity. Pharmacokinetic studies of paclitaxel were also performed. Results: A total of 469 weekly paclitaxel infusions were administered to 30 patients (median, 14 infusions/patient). The median delivered dose-intensity was 91 mg/m²/wk (range, 80 to 108). The overall response rate was 53% (95% confidence interval [Cl], 34% to 72%), with 10% complete responses (CRs) and 43% partial responses (PRs). Median response duration was 7.5 months (range, 2 to 11+). Responses were observed in nine of 18 (50%) patients with prior anthracycline therapy, including six of 12 (50%) with disease progression on anthracycline within 1 year (three of four within 6 months). Therapy was well tolerated and remarkable for a lack of overall and cumulative myelosuppression. Grade 3/4 neutropenia occurred in four patients; febrile neutropenia was not observed. Peripheral neuropathy prohibited dose escalation above 100 mg/m², and grade 3 neuropathy was observed in two of 21 patients at ≤ 100 mg/m². Conclusion: Weekly paclitaxel therapy is active and well tolerated in patients with metastatic breast cancer. Weekly therapy should be considered as a current clinical option for these patients and should be incorporated into future comparative clinical trials.