Testing for HER2
Don’t let HER2 go undetected in GI cancers
Testing for HER2 is crucial for optimizing therapy options in patients with advanced disease. Multiple modalities can be used to identify HER2. However, it is recommended to start HER2 testing with IHC.1-4
While NGS may be used when tissue is limited, NGS alone may overlook HER2 positivity in ~30% of patients with gastroesophageal adenocarcinoma and up to 17% of patients with biliary tract cancer.5,6
IHC identifies HER2 protein expression and is the standard modality for detecting HER2 positivity in gastric cancers2
HER2 status can be confirmed by assessing gene amplification with in situ hybridization (ISH) or fluorescence in situ hybridization (FISH)7
NGS can detect HER2 mutations and determine gene amplification8,9
OPTIMIZED GI CANCER CARE STARTS WITH HER2 TESTING
GI=gastrointestinal; HER2=human epidermal growth factor receptor 2; IHC=immunohistochemistry; NGS=next-generation sequencing.
References
1. Mehta R, Liepa AM, Zheng S, Chatterjee A. Real-world molecular biomarker testing patterns and results for advanced gastroesophageal cancers in the United States. Curr Oncol. 2023;30(2):1869-1881. doi:10.3390/curroncol30020145 2. Bartley AN, Washington MK, Colasacco C, et al. HER2 testing and clinical decision making in gastroesophageal adenocarcinoma: guideline from the College of American Pathologists, American Society for Clinical Pathology, and the American Society of Clinical Oncology. J Clin Oncol. 2017;35(4):446-464. doi:10.1200/JCO.2016.69.4836 3. Sun Y, Puspanathan P, Lim T, Lin D. Advances and challenges in gastric cancer testing: the role of biomarkers. Cancer Biol Med. 2025;22(3):212-230. doi:10.20892/j.issn.2095-3941.2024.0386 4. Choi S, Park S, Kim H, Kang SY, Ahn S, Kim KM. Gastric cancer: mechanisms, biomarkers, and therapeutic approaches. Biomedicines. 2022;10(3):543. doi:10.3390/biomedicines10030543 5. Maron S, Burke K, Gupta P, et al. Concordance between human epidermal growth factor receptor 2 status by immunohistochemistry and next-generation sequencing in tissue and blood samples from gastric and gastroesophageal junction cancers. Presented at: ASCO Gastrointestinal Cancers Symposium; January 23-25, 2025; California, USA. 6. Nakamura Y, Mizuno N, Sunakawa Y, et al. Tucatinib and trastuzumab for previously treated human epidermal growth factor receptor 2-positive metastatic biliary tract cancer (SGNTUC-019): a phase II basket study. J Clin Oncol. 2023;41(36):5569-5578. doi:10.1200/JCO.23.00606 7. Sato Y, Okamoto K, Kawano Y, et al. Novel biomarkers of gastric cancer: current research and future perspectives. J Clin Med. 2023;12(14):4646. doi:10.3390/jcm12144646 8. Niu D, Li L, Yu Y, et al. Evaluation of next generation sequencing for detecting HER2 copy number in breast and gastric cancers. Pathol Oncol Res. 2020;26(4):2577-2585. doi:10.1007/s12253-020-00844-w 9. Zhao D, Klempner SJ, Chao J. Progress and challenges in HER2-positive gastroesophageal adenocarcinoma. J Hematol Oncol. 2019;12(1):50. doi:10.1186/s13045-019-0737-2