TrastuzumabIn HER2 and Hormone Receptor Co-Positive Metastatic Breast Cancer

▲ Trastuzumab is a humanised IgG1 monoclonal antibody, which selectively binds to the human epidermal growth factor receptor 2 (HER2), inhibiting cell proliferation and survival in HER2-dependent tumours.▲ In a randomised phase III trial in postmenopausal women with HER2 and hormone receptor (HR) copositive metastatic breast cancer, median progression-free survival (primary endpoint) was significantly longer in patients receiving intravenous trastuzumab plus oral anastrozole than in those receiving anastrozole alone.▲ Overall response rate and clinical benefit rate were also significantly higher, and median time to disease progression was significantly longer with trastuzumab plus anastrozole versus anastrozole alone.▲ There were no reports of new or unexpected adverse events with trastuzumab plus anastrozole combination therapy in the randomised phase III trial.▲ In a noncomparative phase II study of trastuzumab plus letrozole in postmenopausal women with HER2 and HR co-positive metastatic breast cancer, the majority of adverse events were mild or moderate in severity.