Advancing Care in GI and Biliary Tract Cancers Series Episode 2: HER2 Testing in BTC and GEA

Join moderator Caroline DiCristo, PharmD, Associate Medical Director – Zanidatamab of Jazz Pharmaceuticals, alongside Dr. Paresh Patel and Dr. Masoumeh Ghayouri for the second installment of the Advancing Care in GI and Biliary Tract Cancers podcast series. This episode focuses on HER2 testing in biliary tract cancers (BTC) and gastroesophageal adenocarcinoma (GEA), two GI malignancies where HER2 overexpression is increasingly recognized as an important biomarker for targeted therapy.HER2 has long been a key therapeutic target in breast cancer, but research now shows that HER2 overexpression occurs in up to 30 percent of biliary tract cancers and approximately 20 percent of gastroesophageal adenocarcinomas. As targeted treatment options expand, identifying HER2 status has become a critical step in guiding treatment decisions for patients with advanced disease.Testing Methods and TimingThe discussion explores current guideline recommendations for HER2 testing and the importance of evaluating HER2 status early in the disease course for patients with advanced or metastatic BTC and GEA. Experts review the primary diagnostic methods used to determine HER2 expression:• Immunohistochemistry (IHC): A first-line test that evaluates HER2 protein overexpression in tumor cells. • Fluorescence In Situ Hybridization (FISH): Used to confirm HER2 gene amplification when IHC results are equivocal. • Next Generation Sequencing (NGS): A broader molecular profiling approach that can detect HER2 amplification along with additional actionable mutations.Challenges in GI HER2 TestingThe episode also highlights several practical challenges associated with HER2 testing in GI malignancies. Tumor heterogeneity can lead to variation in HER2 expression between biopsy samples, making accurate tissue sampling and interpretation essential. Additionally, GI cancers follow distinct HER2 scoring guidelines compared with breast cancer, requiring specialized pathology expertise to ensure proper classification.Multidisciplinary CollaborationDr. Patel and Dr. Ghayouri emphasize the importance of close collaboration between oncologists and pathologists when interpreting HER2 test results and determining appropriate treatment strategies. Communication between specialties, including tumor board discussions and repeat biopsies when necessary, helps ensure patients receive the most accurate diagnosis and access to targeted therapies when appropriate.Tune in for a discussion on the growing role of HER2 testing in GI cancers and how precision diagnostics and multidisciplinary care are shaping the future of treatment for patients with biliary tract cancers and gastroesophageal adenocarcinoma.