[Effect of trastuzumab for human esophageal cancer]

The effects on esophageal cancer of monoclonal antibody trastuzumab, directed against the HER2 protein, were evaluated in this study. Immunohistochemical study showed that 90% (45/50) of esophageal cancer specimens expressed HER2 protein, and flow cytometric analysis showed that 4 kinds of human esophageal cancer cells (TT, TE2, TE6, TE10) expressed high levels of HER2 protein. Trastuzumab treatment (100-500 ng/ml) was not able to inhibit the growth of the all kinds of cancer cells, but the combination treatment of trastuzumab and peripheral mononuclear cells resulted in antibody dependent cell-mediated cytotoxicity (ADCC) against the cancer cells TE6 and TE10 in a dose dependent manner. Intraperitoneal injection of trastuzumab at 1 mg/body twice a week for 5 weeks significantly inhibited the growth of mice-bearing xenografts of TE6 and TE10. Our results suggest that trastuzumab therapy is useful in the treatment of human esophageal cancer.