An evaluation of known predictive biomarkers for gastric cancer.

Introduction: Gastric cancer (GC) is the fifth most common malignancy worldwide and it is associated with a poor prognosis, with most cases diagnosed at an advanced stage. In the advanced/metastatic setting, targeted treatments are assuming an increasingly central role. To assess the eligibility to these agents it is essential the evaluation of predictive biomarkers.

Areas covered: This review will provide an analysis of both established and novel predictive biomarkers for GC. Biomarkers currently adopted in clinical practice include HER2 overexpression/ERBB2 amplification, PD-L1 expression and MMR/MSI status, with CLDN18.2 expression as a recent addition. Other predictive biomarkers currently under evaluation include FGFR2b expression, EBV status, MET overexpression/MET amplification, EGFR amplification and VEGF/VEGFR status.

Expert opinion: The increasing number of targeted therapies is revolutionizing the treatment landscape of advanced GC, but some critical challenges remain to be addressed. These include issues related to the amount of available tissue samples, spatial and temporal heterogeneity of biomarkers expression and interobserver variability, as well as issues in the identification of the most appropriate therapeutic strategy in the presence of overlapping biomarkers positivity. To address these problems, interdisciplinary collaboration between pathologists and clinicians is essential.