DNA methylation biomarkers accurately detect esophageal cancer prior and post neoadjuvant chemoradiation

Background: Esophageal cancer (ECa) is associated with high mortality, mostly due to late diagnosis, precluding curativeintent surgery. Hence, neoadjuvant chemoradiation (ChRT) is recommended in most patients regardless of histological subtype. A proportion of these patients, however, achieve complete disease remission and might be spared of radical surgery. The lack of reliable, minimally invasive biomarkers able to detect post- ChRT disease persistence is, nonetheless, a major drawback. We have previously shown that miRNA promotor methylation enables accurate cancer detection in tissues and liquid biopsies but has been seldom explored in ECa patients. Aims: Herein, we sought to unveil and validate novel candidate biomarkers able to detect ECa prior and post ChRT. Materials and Methods: Promoter methylation of miR129-2, miR124-3 and ZNF569 was assessed, using quantitative methylation-specific PCR (qMSP), in tissue samples from normal esophagus, treatment -naive and post- ChRT ECa, as well as in liquid biopsies from ECa patients. Results: All genes disclosed significantly different promoter methylation levels between ECa and normal esophagus, accurately detecting post- ChRT disease, especially for adenocarcinoma. Remarkably, miR129-2(me)/ZNF569(me) methylation panel identified ECa in liquid samples with 53% sensitivity and 87% specificity. Discussion: MiR129-2(me), miR124-3(me) and ZNF569(me) accurately discriminate ECa, either pre-or post- ChRT, from normal tissue, enabling ECa detection. Furthermore, circulalting methylation- based biomarkers are promising minimally invasive tools to detect post- ChRT residual ECa. Conclusion: Overall, our results encourage the use of miRNA methylation biomarkers as accurate ECa detection tools as a novel approach for ChRT response monitoring.