Abstract LB-174: Genome-wide DNA methylation signatures predict the early asymptomatic doxorubicin-induced cardiotoxicity in breast cancer
Authors: Bauer Michael A. , Makhoul Issam , Hsu Ping-Ching , Wei Jeanne , Su L. Joseph , Stone Annjanette , Carter Weleetka , Todorova Valentina K. 
Published: September 2020

Abstract
Background: Doxorubicin (DOX)-induced cardiotoxicity is cumulative-dose-dependent that begins with the first dose, but epigenetic changes after the first dose have not been examined. This study had two aims: Aim 1: to examine whether DNA methylation profile of peripheral blood cells (PBCs) induced by the first cycle of DOX-based chemotherapy can predict the risk of cardiotoxicity; and Aim 2 to determine if there are pretreatment methylation signatures at baseline to predict the risk of cardiotoxicity. Methods: Whole-genome DNA methylation of PBCs from 19 breast cancer patients was examined prior to the start of DOX-based chemotherapy and after the first cycle using Infinium HumanMethylation 450 BeadChip. ChAMP R package was used for the data normalization by the BMIQ algorithm and the COMBAT algorithm to adjust for batch effects. Chemotherapy-induced cardiotoxicity was determined by the assessment of left ventricle ejection fraction (LVEF) with multigated acquisition (MUGA) scan before chemotherapy and at its completion, and any LVEF decline by &gt;10% was considered abnormal. Results: Pre- and post- DOX treatment were compared between patients with abnormal LVEF decline and those who maintained normal LVEF to assess the differences in the cytosine methylation states. The multiple correction testing resulted in a total of 515 differentially methylated CpGs between the patients with abnormal versus normal LVEF post-DOX treatment. There were 379 differentially methylated CpGs at baseline and 136 CpGs after the first cycle which significantly correlated with LVEF status after applying the Holm-Bonferroni method for multiple testing correction. The intersection of the probes resulted in 38 differentially methylated genes (DMG) that when used in hierarchical clustering, correctly clustered baseline samples into those that would result in normal and abnormal LVEF after treatment. DMG genes included SEPT5, IRF6, KCNQ1, NELL1, SIX6, HOXC9 and BCAN. IRF6, which encodes interferon regulatory factor 6, was identified as being significant in the subsequent analysis at the probe and region level. Comparisons of the samples before and after DOX treatment did not result in any probes associated with the treatment that were significant after multiple testing correction. Conclusions: The results from this study provide evidence that DNA methylation profile of peripheral blood cells has the potential to predict the risk of DOX-induced cardiotoxicity. The important finding was that the extent of methylation at baseline correlated with the post-DOX LVEF reduction, indicating that it may have the potential to predict the subsequent development of cardiotoxicity. Further studies with larger cohort of patients are needed to confirm these findings as well as narrowing down candidate methylation markers that can be implemented in a blood test. These finding may help guide treatment or identify patients that need to be followed closely to mitigate heart damage after DOX treatment.
Citation Format: Michael A. Bauer, Issam Makhoul, Ping-Ching Hsu, Jeanne Wei, L. Joseph Su, Annjanette Stone, Weleetka Carter, Valentina K. Todorova. Genome-wide DNA methylation signatures predict the early asymptomatic doxorubicin-induced cardiotoxicity in breast cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr LB-174.