CONGRESS ABSTRACT

Background: immune-checkpoint inhibitors (ICIs), such as Pembrolizumab (a PD-1 monoclonal antibody), have revolutionized cancer therapy. These drugs stimulate T-cell response against the tumor, but due to activation of the immune system, their use can cause immune-related adverse events that may involve the myocardium, leading to the development of fulminant myocarditis. This condition can occur in up to 1% of patients treated with ICIs within the first weeks of therapy, with an associated mortality rate of 33%. Case report: we present the case of a 76-year-old patient who underwent Pembrolizumab administration for malignant melanoma of the left shoulder. Two days after the second dose of Pembrolizumab, the patient developed acute myositis, characterized by very high levels of creatine phosphokinase, myoglobin, and transaminases, accompanied by intense myalgia of the lower limbs. The condition was initially treated by suspending the PD-1 inhibitor and administering methylprednisolone. Nine days later, the patient developed dyspnea, associated with a rise in troponin T levels and a significant arrhythmic burden, characterized by frequent polymorphic ectopic ventricular beats and sustained and nonsustained ventricular tachycardia. Echocardiography showed acute severe left ventricular dysfunction; cardiac magnetic resonance imaging (MRI) findings were suggestive of myocarditis, which rapidly deteriorated into cardiogenic shock, poorly responsive to inotropic and antiarrhythmic therapy, treated with noninvasive ventilation and intravenous immunoglobulins. For this reason, we initiated a second-line therapy with abatacept and ruxolitinib, resulting in progressive improvement and resolution of left ventricular dysfunction. The patient was therefore transferred to a rehabilitation center. However, 20 days later, the patient was again transferred to our ICU for a relapse of biochemical and arrhythmic myocarditis, with no worsening of cardiac function. Therefore, we administered four additional doses of abatacept, continued ruxolitinib therapy, and progressively reduced corticosteroid dosage, with a consistent improvement in arrhythmic burden and troponin T levels until discharge . Conclusion: this case underscores the importance of prompt diagnosis of myocarditis and the initiation of specific treatment in patients receiving ICIs. Furthermore, the effects of ICIs can persist for a long time after discontinuation, thus requiring prolonged specialist observation .