# Epigenome-Wide Association Studies of Proteasome Inhibitor-Related Cardiotoxicity in Patients with Multiple Myeloma

## TL;DR

This study explores how changes in DNA methylation may be linked to heart problems caused by proteasome inhibitors in multiple myeloma patients.

## Contribution

The study identifies epigenetic signals associated with proteasome inhibitor-related heart toxicity, potentially offering new biomarkers.

## Key findings

- Four differentially methylated sites were linked to carfilzomib-related heart toxicity.
- Pathway analyses revealed peroxisome, MAPK, and other biological pathways involved in heart effects.
- No significant methylation sites were found for bortezomib-related heart toxicity.

## Abstract

Proteasome inhibitors (PI) help patients with multiple myeloma live longer, but some develop heart problems. We asked whether epigenetic differences in blood are linked to this risk. Our study analyzed germline DNA samples from 79 participants of the Prospective Study of Cardiac Events During Proteasome Inhibitor Therapy for Relapsed Multiple Myeloma (PROTECT), including 49 treated with carfilzomib and 30 with bortezomib. We performed epigenome-wide association studies (EWAS) to identify differentially methylated sites, regions, and pathways associated with carfilzomib- or bortezomib-related cardiotoxicity. The main outcome was cardiovascular adverse events (CVAEs), including heart failure and arrhythmia. We then performed a meta-analysis to highlight signals common to CVAE associated with both medicines. Our study uncovered epigenetic signals linked to the heart effects of proteasome inhibitors. If confirmed and validated in larger groups, these signals could serve as blood-based biomarkers for PI-related CVAE.

Background/Objectives: Carfilzomib (CFZ) and bortezomib (BTZ) are proteasome inhibitors used as the first-line therapy for relapsed or refractory multiple myeloma (MM) but are associated with cardiovascular adverse events (CVAEs). This study aims to identify differentially methylated positions (DMPs) and regions (DMRs), and enriched pathways associated with CVAEs related to CFZ or BTZ-based treatment. Methods: Baseline germline DNA methylation profiles from 79 MM patients (49 on CFZ and 30 on BTZ) in the Prospective Study of Cardiac Events During Proteasome Inhibitor Therapy (PROTECT) were analyzed. Epigenome-wide analyses were performed within each group, followed by meta-analyses to identify signals common to CVAEs associated with both medicines. Results: Four DMPs were significantly associated with CFZ-CVAEs, including cg15144237 within ENSG00000224400 (p = 9.45 × 10−10), cg00927646 within TBX3 (p = 9.78 × 10−8), and cg10965131 within WDR86 (p = 1.00 × 10−7). One DMR was identified in the FAM166B region (p = 5.46 × 10−7). There was no evidence of any DMPs in BTZ-treated patients, however two DMPs and one DMR reached a suggestive level of significance (p < 1.00 × 10−5): cg09666417 in DNAJC18 (p = 3.41 × 10−7) and cg12987761 in USP18 (p = 5.00 × 10−7), and a DMR mapped to the WDR86/WDR86-AS1 region (p = 8.11 × 10−8). Meta-analysis did not find any significant DMPs, with the top CpG being cg17933807 in GNL2 (p = 7.38 × 10−5). Pathway enrichment analyses identified peroxisome, MAPK, Rap1, adherens junction, phospholipase D, autophagy, and aldosterone-related pathways to be implicated in CVAEs. Conclusions: Our study identified distinct DMPs, DMRs, and pathways enrichment associated with CVAE, suggesting epigenetic contributors to CVAEs and supporting the need for larger validation studies.