Abstract
BACKGROUND: Colorectal cancer (CRC) is a leading cause of cancer-related mortality worldwide. In cases of metastatic CRC (mCRC) that are resistant to conventional chemotherapy-based treatments, the efficacy of available therapeutic options is typically low. CRC exhibiting overexpression or amplification of the human epidermal growth factor receptor 2 (HER2) gene has shown responsiveness to HER2-targeted therapies. CASE SUMMARY: We present the case of a 69-year-old woman diagnosed with mCRC with an NRAS p.G12V mutation and microsatellite stability, identified through tumor sequencing, along with HER2 overexpression detected by immunohistochemistry. She exhibited an excellent response to disitamab vedotin-containing therapy. To our knowledge, this is the first reported case of mCRC with HER2 overexpression and an NRAS p.G12V mutation achieving a remarkable clinical response to anti-HER2 therapy. CONCLUSION: Disitamab vedotin demonstrates promising anti-tumor effects in HER2-overexpressing mCRC, offering patients an additional treatment option.