Efficacy and Safety of Combined Trastuzumab and Paclitaxel Therapy as a Second-Line Treatment in Women with Metastatic Breast Cancer: A Single Institutional Experience

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Background: In breast cancer, HER-2 overexpression suggests s poor prognosis. Trastuzumab is a humanized monoclonal antibody with specificity to the HER-2 protein. We evaluated the safety and efficacy of combined trastuzumab and paclitaxel therapy in women with metastatic breast cancer.
Patients and Methods: Combination chemotherapy was given to patients with HER-2 overexpressing metastatic breast cancer. All patients had previously received one or more chemotherapy treatments. Patients received a loading trastuzumab dose of 4 mg/kg intravenously (i.v.), followed by 2 mg/kg maintenance dose at weekly intervals. A paclitaxel dose of 80 mg/m² was administered on the same day as the trastuzumab infusion.
Results: A total of 53 patients were examined. Seventy percent received two or more prior chemotherapy treatments for metastatic breast cancer, and 66.0% of patients had two or more metastatic sites. The overall response rate to our approach was 37.7%. Median time to progression was 12.0 months. Grade 3/4 neutropenia was seen in only 11.3% of patients. Peripheral neuropathy occurred in 65.1% of patients after seven treatments, requiring us to change to biweekly paclitaxel administration in 16 patients. Most of them were able to continue the treatment. Other toxicities were mild and tolerable.
Conclusion: Combined trastuzumab and paclitaxel therapy, administered as second-line or later treatment, produced lasting objective responses and was well tolerated by women with HER-2 overexpressing metastatic breast cancer. A major obstacle to continuing treatment was peripheral neuropathy. However, modifying the interval to every 2 weeks enabled us to continue the treatment. This combination chemotherapy was safely performed in our outpatient clinic.