Metastatic colorectal cancer is the second most common cause of cancer death. Standard chemotherapy in combination with targeted therapies represent the backbone for the treatment of advanced disease. However, options are limited for patients progressing on these regimens. Genetic testing can offer patients the opportunity to benefit from novel therapies, namely immune checkpoint inhibitors in microsatellite instability-positive tumors. HER2 overexpression has recently emerged as a potentially targetable tumor marker in colorectal cancer (CRC). Despite the absence of approvals for anti-HER2 therapies in CRC, many agents such as trastuzumab and pertuzumab were tested and demonstrated significant antitumor activity, even in heavily pretreated patients. Early trials are also evaluating lapatinib, T-DM1, tucatinib and other anti-HER2 agents in patients with metastatic CRC, with promising results.
Keywords: HER2; TDM-1; amplification; colorectal cancer; lapatinib; overexpression; pertuzumab; trastuzumab; trastuzumab deruxtecan; tucatinib.