Establishment of epigenetic markers to predict irradiation efficacy against oropharyngeal cancer. Issue 4 (27th February 2020) - Kurokawa, Tomoya
Abstract: Irradiation, or chemoradiotherapy, is a curative treatment for oropharyngeal squamous cell carcinoma (OPSCC). Its invasiveness, however, can often negate its efficacy. Therefore, developing methods to predict which patients would benefit from irradiation is urgent. Promoter DNA hypermethylation was recently reported to correlate with favorable OPSCC prognosis. It is still unclear, however, whether there is an association between promoter DNA methylation and response to irradiation. In this study, we analyzed DNA methylation in the specimens from 40 OPSCC patients who had undergone irradiation, using the Infinium assay. Our results showed significant correlation between high levels of promoter DNA methylation and better response to treatment ( P < 0.01). We used the 10 most differentially‐methylated genes between responders and non–responders to develop a panel of predictive markers for efficacy. Our panel had high sensitivity, specificity and accuracy (92%, 93% and 93%, respectively). We conducted pyrosequencing to quantitatively validate the methylation levels of 8 of the 10 marker genes ( ROBO1, ULK4P3, MYOD1, LBX1, CACNA1A, IRX4, DPYSL3 and ELAVL2 ) obtained by Infinium. The validation by pyrosequencing showed that these 8 genes had a high prediction performance for the training set of 40 specimens and for a validation set of 35 OPSCC specimens, showing 96% sensitivity, 89% specificity and 94% accuracy. Methylation of these markers correlated significantly with better progression‐free and overall survival rates, regardless of human papillomavirus status. These results indicate that increased DNA methylation is associated with better responses to irradiation therapy and that DNA methylation can help establish efficacy prediction markers in OPSCC. Abstract : We investigated the association between promoter DNA methylation and irradiation efficacy against oropharyngeal squamous cell carcinoma (OPSCC), so that an appropriate stratification by establishing molecular classifier markers could help therapeutic optimization and de–escalation of OPSCC treatment. A methylation marker panel was developed to act as an efficacy predictor with high sensitivity, specificity and accuracy in the training samples. It is noteworthy that the utility of the established prediction marker panel was consistent regardless of human papillomavirus status, and that multivariate analysis verified the methylation status of the marker panel as the only independent prognostic factor.