Safety and efficacy of trastuzumab every 3 weeks combined with cytotoxic chemotherapy in patients with HER2-positive recurrent breast cancer: Findings from a case series

Background: Trastuzumab has been repeatedly shown to result in significant clinical benefits and was subsequently accepted as the treatment of choice for HER2-positive advanced breast cancer - particularly as first-line treatment in combination with taxanes and as monotherapy in the second-line or third-line setting. Trastuzumab is currently licensed as a weekly treatment, although a 3-weekly schedule could be used conveniently in combination with other cytotoxic agents that are administered on a 3-weekly basis in metastatic breast cancer. Patients and Methods: We determined the safety of i.v. trastuzumab (8 mg/kg followed by 6 mg/kg) every 3 weeks in combination with chemotherapeutic agents administered in 3-weekly courses (docetaxel, vinorelbine and capecitabine) in 31 patients with HER2-positive recurrent locoregional and/or metastatic breast cancer. Results: 3-weekly trastuzumab appeared to be as well tolerated as the standard once-weekly schedule. All myelosuppressive adverse events and the majority of non-hematological adverse events were typical and characteristic of the individual concomitant cytotoxic agents. Transient trastuzumab-related infusion reactions occurred in 5 patients and 1 patient developed cardiac dysfunction, which recovered after discontinuation of trastuzumab. Efficacy appeared favourable: 18 clinical responses (3 complete and 15 partial) and 8 disease stabilizations gave an overall response rate of 58% (70% in the 20 patients receiving first-line therapy). Median progression-free and overall survival times were 9.9 months (95% Cl: 6.3 - 13.5) and 23.1 months (95% Cl: 19.2 - 27.0), respectively. Conclusions: These findings will likely encourage further evaluation of this more convenient 3-weekly trastuzumab regimen in patients with HER2-positive metastatic breast cancer.