Abstract 12898: Eosinophilic Myocarditis Following Osimertinib Treatment for Epidermal Growth Factor Receptor Mutated Lung Adenocarcinoma

Abstract

A 60-year-old man with oligometastatic adenocarcinoma of the lung presented with symptoms of heart failure 6 weeks after initiation of treatment with osimertinib, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor. A transthoracic echocardiography (TTE) showed a moderately sized pericardial effusion, mildly increased left ventricular (LV) wall thickness, and mildly depressed LV ejection fraction (45-50%), without tamponade physiology. His TTE prior to treatment initiation was normal. He endorsed chest pain across the entire chest that had started on the second day after initiation of osimertinib and was worse when laying down. His serum troponin I concentration was elevated to 10.6 ng/mL upon admission and ECG showed sinus tachycardia. He was carefully diuresed with some improvement in symptoms. A peripheral eosinophilia was noted, which raised suspicion for eosinophilic myocarditis. A cardiac magnetic resonance imaging confirmed a mildly reduced LVEF of 51% and mildly increased LV wall thickness. There was diffuse late gadolinium enhancement throughout the entire myocardium, with increased T1 and T2 signals and the extracellular volume was increased to 40%, supporting a diagnosis of perimyocarditis. A left and a right heart catheterization were subsequently undertaken. His coronary arteries were normal and the right heart cathetherization showed unremarkable hemodynamics, including a right atrium pressure of 6 mm Hg, right ventricular pressure of 34/6 mm Hg, pulmonary artery pressure of 33/9 mm Hg, and a pulmonary capillary wedge pressure of 10 mm Hg. A right heart biopsy revealed a dense eosinophilic infiltration of the myocardium, consistent with an eosinophilic hypersensitivity reaction, manifesting as myocarditis. High dose prednisone was initiated and after 2 months of treatment, repeat TTE showed resolution of his pericardial effusion and normalization of the LV wall thickness and LVEF (65%). This case illustrates the value of multi-modality imaging and endomyocardial biopsy to diagnose rare complications of novel, targeted cancer therapeutics.