PCSK9 Inhibitor Inclisiran Attenuates Cardiotoxicity Induced by Sequential Anthracycline and Trastuzumab Exposure via NLRP3 and MyD88 Pathway Inhibition

Anthracyclines and trastuzumab-related cardiotoxicity represents a significant clinical challenge in cancer therapy, often limiting treatment efficacy and patient survival. The underlying mechanisms of cardiotoxicity involve the activation of NLRP3 and the MyD88-dependent signaling pathway. Proprotein convertase subtilisin/kexin type 9 inhibitors (PCSK9i), such as inclisiran, are known for their lipid-lowering effects, but emerging data indicates that they may also exert pleiotropic benefits beyond cholesterol reduction. This study investigates whether inclisiran can mitigate the cardiotoxic effects of anthracyclines and trastuzumab through reduction of NLRP3 activation and MyD88 signaling, independently of its effects on dyslipidemia. We aimed to evaluate whether inclisiran reduces anthracycline and trastuzumab-induced cardiotoxicity by modulating NLRP3 and MyD88 signaling, independent of its effects on dyslipidemia. Human cardiomyocytes (AC16 cell line) were exposed to subclinical concentration of doxorubicin, (200 nM) and trastuzumab in sequential therapy (200 nM), alone or in combination with inclisiran (100 nM) for 24h. After the incubation period, we performed the following tests: determination of cardiomyocytes apoptosis, analysis of intracellular reactive oxygen species, lipid peroxidation products (including malondialdehyde and 4-hydroxynonenal), intracellular mitofusin-2 and Ca⁺⁺ levels. Troponin and BNP were quantified through selective ELISA methods. Confocal Laser Scanning Microscope was used to study cardiomyocytes morphology and F-actin staining after treatments. Moreover, pro-inflammatory studies were also performed, including the intracellular expression of NLRP-3, MyD-88 and twelve cytokines/growth factors involved in cardiotoxicity (IL-1α, IL-1β, IL-2, IL-4, IL-6, IL-10, IL-12, IL17-α, IFN-γ, TNF-α, G-CSF, GM-CSF). Inclisiran co-incubated with doxorubicin and trastuzumab exerts significant cardioprotective effects enhancing cell viability of 88,9% compared to only DOXO/TRA treated cells (p<0,001 for all). Cell necrosis and apoptosis were reduced. Significant reduction of oxidative stress, ferroptosis and intracellular levels of NLRP-3, MyD88, CCL-2, p65NF-KB, IL-1α, IL-1β, IL-6, IL-12, IL17-α, TNF-α, G-CSF were seen in inclisiran group vs only DOXO/TRA group (p<0.001). For the first time, PCSK9i inclisiran exerts significant anti-inflammatory effects to reduce anthracycline-HER-2 blocking agent mediated cardiotoxicity through NLRP-3 and Myd-88 related pathways. The overall picture of the study warrant on the use of PCSK9i in primary prevention of CTRCD in cancer patients, independently from dyslipidemia.