Molecular biomarkers in gastro-esophageal cancer: recent developments, current trends and future directions

Francesca Battaglin,Heinz-Josef Lenz,Madiha Naseem,Alberto Puccini

doi:10.1186/s12935-018-0594-z

Abstract

Gastro-esophageal adenocarcinomas (GEA) represent a severe global health burden and despite improvements in the multimodality treatment of these malignancies the prognosis of patients remains poor. HER2 overexpression/amplification has been the first predictive biomarker approved in clinical practice to guide patient selection for targeted treatment with trastuzumab in advanced gastric and gastro-esophageal junction cancers. More recently, immunotherapy has been approved for the treatment of GEA and PD-L1 expression is now a biomarker required for the administration of pembrolizumab in these diseases. Significant progress has been made in recent years in dissecting the genomic makeup of GEA in order to identify distinct molecular subtypes linked to distinct patterns of molecular alterations. GEA have been found to be highly heterogeneous malignances, representing a challenge for biomarkers discovery and targeted treatment development. The current review focuses on an overview of established and novel promising biomarkers in GEA, covering recent molecular classifications from TCGA and ACRG. Main elements of molecular heterogeneity are discussed, as well as emerging mechanisms of primary and secondary resistance to HER2 targeted treatment and recent biomarker-driven trials. Future perspectives on the role of epigenetics, miRNA/lncRNA and liquid biopsy, and patient-derived xenograft models as a new platform for molecular-targeted drug discovery in GEA are presented. Our knowledge on the genomic landscape of GEA continues to evolve, uncovering the high heterogeneity and deep complexity of these tumors. The availability of new technologies and the identification of promising novel biomarker will be critical to optimize targeted treatment development in a setting where therapeutic options are currently lacking. Nevertheless, clinical validation of novel biomarkers and treatment strategies still represents an issue.

Highlights

Gastric and esophageal adenocarcinomas, collectively referred to as gastro-esophageal adenocarcinomas (GEA), represents a severe global health issue
Of note, based on recent molecular subtypes, Epstein-Barr virus (EBV)-positive and microsatellite instability (MSI)-H Gastric cancer (GC) emerge as the best candidates for immunotherapy based on the increased programmed cell death-ligand 1 (PD-L1) expression associated with these subtypes and the high tumor mutational load in MSI-H GEA, which has been shown to correlate with a greater benefit from anti-programmed cell death protein 1 (PD-1)/PD-L1 blockade [87]
Their study included a pilot analysis of cellfree DNA which showed both concordance and discordance with matched primary tumor (PT) and metastatic lesions (MLs) results, as sequencing of cfDNA was able to identify in some cases alterations not observed in the PTs, but at the same time failed in other cases to show the presence of known alterations involving genes such as HER2 and FGFR found in PTs

Summary

Introduction

Collectively referred to as gastro-esophageal adenocarcinomas (GEA), represents a severe global health issue. Of note, based on recent molecular subtypes, EBV-positive and MSI-H GCs emerge as the best candidates for immunotherapy based on the increased PD-L1 expression associated with these subtypes and the high tumor mutational load in MSI-H GEA, which has been shown to correlate with a greater benefit from anti-PD-1/PD-L1 blockade [87].

Results

Conclusion