The HER2 gene (also known as HER2/neu and ErbB2 gene) is overexpressed in 20-30% of human breast cancers and leads to a particularly aggressive form of the disease. Trastuzumab,a humanized anti-HER2/neu receptor monoclonal antibody, has been proved valuable treatment for HER2-positive breast cancer patients.The combination of trastuzumab with chemotherapy has been shown to increase both survival and response rate, in comparison to trastuzumab alone. CMAB302, a biosimilar of trastuzumab, was developed by Shanghai CP Guojian Pharmaceutical Co.Ltd. Previous Phase I study showed that CMAB302 was well tolerated as monotherapy and the pharmacokinetic data exhibited a non-linear profile over the dose range of 100 to 500 mg, similar to that of trastuzumab. In this study, efficacy and safety of CMAB302 as a single agent or in combination with vinorelbine were evaluated in patients with HER2-overexpressing metastatic breast cancer.
