Objective: Combined therapy with bevacizumab and paclitaxel (BP regimen) as a first-line treatment has proven highly effective with good tolerance for patients with metastatic breast cancer (MBC). The objective of this study was to examine the efficacy and safety of the BP regimen for Japanese patients with MBC in real-world clinical settings.
Methods: From June 2012 through May 2014, we recruited 94 patients at 10 medical institutions. The primary endpoint was time to treatment failure (TTF), and the secondary endpoints were overall survival (OS) and safety. Objective response was assessed according to the Response Evaluation Criteria in Solid Tumors. Adverse events (AEs) were graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events version 4.0-Japan Clinical Oncology Group.
Results: Nighty patients with MBC (mean 58 years, range: 34-80 years) were enrolled, and 60 (66.6%) and 52 (57.7%) had undergone prior chemotherapy as adjuvant treatment and treatment for MBC, respectively. Median TTF was 6.2 months (95% confidence interval [CI], 4.2-8.3 months), and median OS was 15.4 months (95% CI, 12.0-18.9 months). The overall response rate was 67.8% (95% CI: 57.1-77.2%). A total of 28 patients (31.1%) required a dose reduction of paclitaxel. Forty-five, 42, and 3 patients received the initial doses of 90, 80, and 60 mg/m2, respectively. Among patients who received the initial doses of 90 mg/m2, 13 patients (28.9%) unexpectedly required a dose reduction of ≥20 mg/m2. The BP regimen was discontinued for 66 (73.3%) of the 90 patients, 52 (57.7%) of whom experienced "disease progression." Grade 3/4 hematologic AEs developed in 51 patients (56.6%), with leukopenia and neutropenia in 16 patients (17.8%) and 21 patients (23.3%), respectively. Grade 3 nonhematologic AEs developed in 8 patients (8.9%), with the most common nonhematologic AE of peripheral neuropathy in 4 patients (4.4%). No Grade 4 nonhematologic AEs developed. Peripheral neuropathy [56 patients (62.2%) ], nail discoloration [53 patients (58.9%) ], and fatigue [51 patients (56.7%) ] were the most predominant AEs-the known AEs of paclitaxel.
Conclusions: The BP regimen was active and well tolerated in the real-world clinical settings. As many as 28.9% of patients who received the initial dose of 90 mg/m2 required a dose reduction of paclitaxel by 20 mg/m2. Therefore, there is a need to find a therapeutic regimen that is less likely to result in dose reductions for patients with MBC who undergo a BP regimen using the initial paclitaxel dose of 90 mg/m2.
Keywords: bevacizumab; cohort study; combined therapy; metastatic breast cancer; paclitaxel.