P-158: Carfilzomib-induced acute cardiotoxicity is mediated through angiotensin and caused by cardiomyocyte energy depletion

Abstract

<h3>Background</h3> Carfilzomib (CFZ) treatment increases the survival of patients with relapsed/refractory MM, but it is associated with a higher incidence of cardiovascular adverse events not commonly observed after bortezomib (BTZ). Both CFZ and BTZ inhibit the rate-limiting proteasome beta 5 subunit activity at lower concentrations. However, only CFZ co-inhibits the activity of proteasome beta 5 and beta 2 subunits at higher doses, in contrast to the beta 5 and beta 1 co-inhibition provided by high dose BTZ. We hypothesized that the unique beta 5 and beta 2 subunit inhibition pattern explains the CFZ-related acute cardiotoxicity. <h3>Methods</h3> Isolated primary murine cardiomyocytes treated with BTZ, CFZ or specific inhibitors for the beta 5, beta 2 and beta 1 proteasome subunits were used as in vitro model to assess cardiomyocyte contractility by time lapse video-microscopy in conjunction with motion vector image analysis. The effects of acute proteasome inhibition after CFZ or BTZ treatment was studied in vivo in the heart and bone marrow 1 hour post treatment with a multi-omics approach at the single cell-genomic, proteomic and metabolomic level. Selectivity of proteasome subunit inhibition was confirmed with the activity based chemical probes. All data was evaluated with R v.3.5.1 (2018-07-02) and Matlab 2020a. <h3>Results</h3> CFZ resulted in co-inhibition of beta 5 and beta 2 proteasome subunit activity in cardiomyocytes, in contrast to beta 5 and beta 1 inhibition by BTZ. CFZ, or the combination of beta 5 and beta 2 specific proteasome inhibitors induced acute impairment of cardiomyocyte contractility, in contrast to BTZ or the combination of beta 5 and beta 1 inhibitors. CFZ caused significant quantitative proteomic changes related to cardiomyocyte metabolism that differed from BTZ-related proteomic changes. Single-cell RNA sequencing of murine hearts revealed that CFZ impairs ATP synthesis in cardiomyocytes. Metabolomic analysis of murine hearts revealed increased levels of angiotensin after CFZ treatment, in contrast to BTZ treatment. Co-treatment of cardiomyocytes with CFZ and valsartan prevented CFZ-induced cardiomyocyte toxicity. Thus, our results suggest a key role of the renin-angiotensin system in the pathogenesis of CFZ-induced acute cardiac toxicity. <h3>Conclusion</h3> Our data suggest that CFZ specifically impairs cardiac contractility in a dose-dependent manner through its unique proteasome beta 5 and beta 2 subunit co-inhibition pattern, in contrast to BTZ. CFZ leads to more efficient functional proteasome inhibition in cardiomyocytes, impairs cardiomyocyte metabolism and activates the local renin-angiotensin-system, inducing acute cardiotoxicity. Inhibition of the renin-angiotensin system pathway with valsartan mitigated cardiomyocyte contractile impairment, providing a rational strategy to prevent CFZ-induced acute cardiac toxicity.