Supplementary Material for: A New Hope: Dual HER2 Blockade and Chemotherapy in HER2-Amplified Colorectal Cancer - A case report and literature review

Monoclonal antibodies targeting epidermal growth factor receptors (EGFRs) are currently the preferred targeted therapeutic agents for RAS wild-type, left-sided metastatic colorectal cancer (mCRC). Nonetheless, certain molecular alterations within mCRC confer resistance to anti-EGFR monoclonal antibody therapy, notably alterations involving human epidermal growth factor receptor 2 (HER2). Colorectal cancer characterized by HER2 amplification or overexpression may have markedly different prognoses than HER2-negative colorectal cancer does. Recent clinical trials have demonstrated that dual HER2 blockade leads to significant improvements in clinical outcomes for these patients. In this study, we present a case in which HER2-positive mCRC was successfully treated with HER2-targeted agents combined with chemotherapy, resulting in favorable clinical outcomes.