Current and future therapies for targeting HER2 mutations in gastrointestinal cancer

Introduction: Gastrointestinal (GI) cancers altogether represent the most common cancer type. HER2 is found to be present in nearly all histologic types of GI cancers in variable degrees of expression. Over the last decade, substantial advances have been made in targeting HER2-positive cancers. Areas covered: The present review summarizes the current progress and future directions for HER2 targeted therapies in GI cancers, including esophagogastric, pancreaticobiliary, and colon cancers. To date trastuzumab is the only anti-HER2 therapy approved for metastatic esophagogastric adenocarcinoma. Efforts are ongoing to expand the therapeutic role of HER2 to other GI cancers and overcome mechanisms of drug resistance. Novel agents and combinations are being tested in most HER2 positive GI cancers including early stage disease. These are of recent interest in colorectal cancer with studies indicating that HER2 overexpression might increase resistance to anti-EGFR therapy and may be potentially targeted. Expert commentary: With the current ability to sequence tumors and detect genetic alterations, emphasis should be put on genomically-selected pan-tumor targeted therapies. HER2 is a perfect example of a promising drug target in GI cancers.