Abstract 16249: A Case of Myocarditis and Pneumonitis Associated With Pembrolizumab Therapy

Abstract

Introduction: Immune checkpoint inhibitors (ICI) are a novel therapy that activates antitumor immunity but can have varied immune-related adverse effects. As ICI therapy is used to treat malignancy, cases of autoimmune myocarditis and heart failure increase, thought to be due to PD-1 inhibition, which may be potentially fatal. Case presentation: A 37 yo female with history of autoimmune hepatitis and stage III melanoma on Pembrolizumab (ninth cycle 1.5 months prior) presented with chest pain, tachycardia, fatigue, dyspnea, and fever. Lab studies were notable for elevated troponin, lactic acidosis, and disseminated intravascular coagulation (DIC). CT thorax showed asymmetric ground glass opacities, concerning for ICI pneumonitis. Echocardiogram showed an LVEF of 15% with global hypokinesis. She was treated for severe sepsis, DIC, and respiratory failure, temporarily requiring intra-aortic balloon pump. Heart failure guideline-directed medical therapy (GDMT) was started. Clinical presentation was concerning for acute myocarditis related to ICI therapy as a cause for new cardiomyopathy. A cardiac MRI (CMR) revealed subepicardial late gadolinium enhancement (LGE) along the basal inferior/inferolateral wall segments concerning for myocarditis. Corticosteroids with a prolonged taper were started. Endomyocardial biopsy of the septum (EMB) was negative. Her clinical status improved and repeat echo showed LVEF recovery up to 45%. Discussion: Endomyocardial biopsy (EMB) provides definitive diagnosis of myocarditis and is recommended (Class I) for new-onset heart failure with hemodynamic compromise and/or arrhythmias. Although our patient’s EMB was negative (likely due to limitation of sample location), she met the 2013 ESC guideline diagnostic criteria for myocarditis with elevated troponin, functional and structural abnormalities on cardiac imaging. With increased utilization of ICI therapy in the management of aggressive malignancies, it is important to monitor for potentially adverse effects such as autoimmune myocarditis. Standard treatment is prompt initiation of corticosteroids, though newer studies report successful treatment with immunomodulators, such as abatacept and ruxolitinib, if steroids are unsuccessful.