Protective effects of trimetazidine against pembrolizumab-induced cardiac injury: biochemical and immunohistochemical evaluation

Abstract Pembrolizumab, an immune checkpoint inhibitor targeting programmed cell death protein-1 (PD-1), has substantially improved cancer treatment outcomes but may induce immune-related cardiotoxicity characterized by oxidative stress, inflammation, and apoptosis. Trimetazidine is a metabolic modulator with antioxidant and cardioprotective properties. This study aimed to investigate the protective effects of trimetazidine against pembrolizumab-induced cardiac injury in rats. Twenty-four male Wistar rats were randomly assigned to four groups (n = 6 per group): healthy control (HG), trimetazidine (TMZ, 5 mg/kg/day), pembrolizumab (PBZ, 5 mg/kg/day), and trimetazidine plus pembrolizumab (TZPZ). The treatments were administered for seven consecutive days. At the end of the experimental period, cardiac tissues were analyzed for malondialdehyde (MDA), total glutathione (tGSH), superoxide dismutase (SOD), catalase (CAT), interleukin-1β (IL-1β), and interleukin-6 (IL-6). Serum cardiac troponin I (cTnI) levels were determined. Oxidative DNA damage and apoptosis were evaluated immunohistochemically using 8-hydroxy-2′-deoxyguanosine (8-OHdG) and cleaved caspase-3 staining. Pembrolizumab significantly increased cardiac MDA, IL-1β, IL-6, and serum cTnI levels, while markedly reducing tGSH, SOD, and CAT levels (all p < 0.001). Severe 8-OHdG immunopositivity and moderate caspase-3 immunopositivity were observed in the PBZ group. Trimetazidine treatment significantly reduced MDA levels and improved tGSH, SOD, and CAT levels. It also suppressed the production of pro-inflammatory cytokines, reduced serum cTnI levels, and markedly decreased 8-OHdG and caspase-3 immunoreactivity (all p < 0.001). No significant differences were observed between the healthy control and trimetazidine-alone groups. Trimetazidine attenuated pembrolizumab-induced cardiac injury, accompanied by reductions in oxidative stress, inflammation, oxidative DNA damage, and apoptosis. These findings suggest that trimetazidine may represent a promising adjunctive cardioprotective strategy for preventing pembrolizumab-associated cardiotoxicity. Further mechanistic and clinical studies are warranted to confirm these findings and facilitate their translation into clinical practice.