Singal, Pawan K.

ABSTRACT Although Doxorubicin (Dox) is an effective anticancer drug, it can cause severe cardiotoxicity. While several mechanisms have been proposed to explain Dox‐induced cardiomyopathy (DIC), strategies to prevent it remain limited. In previous research on isolated cardiomyocytes, we identified that Empagliflozin (EMPA), an antidiabetic drug, mitigated Dox‐induced ER stress and apoptosis. In this in vivo study using rats, we further investigated EMPA's potential in preventing and treating DIC. Rats administered a cumulative dose of 15 mg/kg Dox exhibited significant cardiovascular damage, including left ventricular cavity dilation, decreased left ventricular ejection fraction (LVEF), ER dilation, mitochondrial defects and vacuole formation. These structural changes were linked to the activation of ER‐stress pathways (PERK, IRE1 and ATF6) and upregulation of apoptotic proteins initiated by ER stress. When EMPA (10 mg/kg/day) was administered either prophylactically or concurrently with Dox, it significantly attenuated adverse LV remodelling and preserved LVEF. Additionally, EMPA prevented ER stress and subsequent apoptosis in the myocardium of the Dox + EMPA‐treated group. These findings suggest that EMPA offers cardioprotective benefits in DIC, likely through the inhibition of ER‐stress‐induced myocardial injury.

The recent introduction of novel anticancer therapies, including bevacizumab (BVZ) and sunitinib (SNT), is associated with an increased risk of cardiotoxicity. However, early identification of left ventricular (LV) systolic dysfunction may facilitate dose modification and avoid the development of advanced heart failure. Using a murine model of BVZ- and SNT-mediated cardiotoxicity, we investigated whether cardiac biomarkers and/or tissue velocity imaging (TVI) using echocardiography can detect early changes in cardiac function, before a decrease in LV ejection fraction is identified. A total of 75 wild-type C57Bl/6 male mice were treated with either 0.9% saline, BVZ, or SNT. Serial monitoring of blood pressure, high-sensitivity troponin I, and echocardiographic indexes were performed over a 14-day study period, after which the mice were euthanized for histological and biochemical analyses. Mice treated with either BVZ or SNT developed systemic hypertension as early as day 7, which increased by day 14. Cardiac biomarkers, specifically high-sensitivity troponin I, were not predictive of early LV systolic dysfunction. Although conventional LV ejection fraction values decreased at day 13 in mice treated with either BVZ or SNT, TVI confirmed early LV systolic dysfunction at day 8. Histological and biochemical analysis demonstrated loss of cellular integrity, increased oxidative stress, and increased cardiac apoptosis in mice treated with BVZ or SNT therapy at day 14. In a murine model of BVZ- or SNT-mediated cardiomyopathy, noninvasive assessment by TVI detected early LV systolic dysfunction before alterations in conventional echocardiographic indexes.