Therapeutically relevant predictive biomarkers in esophageal adenocarcinoma

Background: The vast majority of esophageal adenocarcinomas (EAC) arise from Barrett's mucosa. Significant progress has been made over the past 10 years in the molecular mechanisms underlying the malignant transformation of Barrett's mucosa and the molecular characteristics of established EACs. From these findings, therapeutic options have been established (or are in the process of being established). For some of these therapies, biomarkers exist that can be tested on individual tumor tissue and whose presence is associated with an increased likelihood of response to specific drugs.Objectives: To present the current knowledge of therapeutically relevant molecular alterations and target proteins and their testing in EAC and adenocarcinomas of the esophagogastric junction zone (EGJ carcinomas).Materials and methods: A literature search in PubMed and Medline was performed.Conclusions: Therapeutically relevant molecular alterations and target proteins in EAC/EGJ are HER2/neu (high and low), programmed death ligand-1 (PD-L1), mismatch repair protein deficiency/microsatellite instability, (dMMR/MSI), BRCA1/BRCA2 or BRCAness (DNA repair deficiency), FGFR2b, Claudin 18.2, neurotrophic tropomyosin receptor kinase (NTRK), and some potential additional alterations that may gain importance in the future. Standard testing should include HER2/neu, PD-L1, and the MMR proteins.