Trastuzumab administration in patients with breast cancer is associated with increased primary tumor expression of CEACAM1.
Trastuzumab, a monoclonal antibody targeted against the human epidermal growth factor receptor 2 (HER2) is utilized for the treatment of human breast cancer (1, 2), but a complete understanding of how tumor signal transduction is modulated by trastuzumab treatment is lacking. By mining published and public microarray and gene expression data (3, 4) from the primary tumors of patients treated with trastuzumab, we found that the cell adhesion molecule CEACAM1 was among the genes most differentially expressed in the primary tumors of patients treated with trastuzumab. Thus, a molecule whose expression is predictive of metastatic disease in patients with malignant melanoma (5) and whose expression in melanoma cell lines can support invasive properties (6) is expressed at significantly higher levels in the primary tumors of patients treated with trastuzumab for breast cancer.