Osimertinib induces reversible cardiac dysfunction through the GATA4-MYLK3-MYL2 axis

Osimertinib is a third-generation tyrosine kinase inhibitor targeting activating mutations of epidermal growth factor receptor with remarkable therapeutic efficacy against non-small cell lung carcinoma. However, its use has been limited by associated cardiotoxicity, primarily with heart failure. Herein, this study aims to better understand the mechanisms underlying osimertinib cardiotoxicity and explore cardioprotective strategies.

This study leverages an in vitro model of human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) and a clinically relevant in vivo mouse model of osimertinib cardiotoxicity by co-employing transverse aortic constriction to mimic haemodynamic stress in cancer patients.

Osimertinib treatment leads to significant contractile dysfunction in mice without cell death, inflammation, or fibrosis. By leveraging single-nucleus RNA sequencing of mouse heart tissues and in vitro assays of human iPSC-CMs, the study reveals significant downregulation of MYLK3 and a subsequent decrease in MYL2 phosphorylation with marked sarcomere disarray as the main mechanism of osimertinib cardiotoxicity. GATA4 is further identified as a putative target of osimertinib, connecting its decreased phosphorylation to repressed MYLK3 transcription. The reversibility of osimertinib-induced cardiac dysfunction upon discontinuation of osimertinib treatment supports the hypothesis that transient sarcomere disruption, rather than permanent cellular damage, serves as the key underlying mechanism. Finally, the myosin activator omecamtiv is shown to be effective in preventing osimertinib cardiotoxicity.

These findings suggest that osimertinib causes reversible cardiac dysfunction by disrupting MYL2 phosphorylation via GATA4 dephosphorylation-mediated suppression of MYLK3 and highlight the potential of myosin activation as a preventive or rescue strategy for osimertinib cardiotoxicity.