ATYPICAL CASE OF HYPEREOSINOPHILIA MANAGED WITH AN ATYPICAL CHOICE OF BIOLOGIC

Abstract

Introduction Hypereosinophilia (HE) describes a rare and clinically-heterogeneous disease-spectrum. We present a case of a 71-year-old man with severe, unexplained HE and clinical response to benralizumab therapy. Case Description A 71-year-old man with prior history of large granular lymphocytic (LGL) leukemia (in-remission) and severe persistent asthma presented emergently with a 2-week history of fatigue, dyspnea and productive cough. He was afebrile and tachycardic with course breath sounds. The absolute eosinophil count (AEC) (6.2 × 109/L), troponin (1.24 ng/mL) and B-type natriuretic peptide (1898 pg/mL) were elevated. CT thorax demonstrated bibasilar parenchymal disease and ground-glass opacities. The patient received intravenous methylprednisolone (80 mg three-times-daily) for presumed eosinophilic myocarditis. Troponins down-trended, and AEC resolved (0.0 × 109/L) (day 3). A subsequent echocardiogram indicated no fibrosis or valvular disease. Infectious work-up, FIP1L1-PDGFRA and anti-neutrophil cytoplasmic antibodies were negative. There were no signs of LGL recurrence. The patient was discharged on prednisone, which he self-discontinued due to agitation, insomnia and increased appetite. AEC rose to 1.4 × 109/L (post-discharge-day 55) and respiratory symptoms recurred. To optimize management, the patient started benralizumab, a humanized monoclonal antibody to IL-5Rα. After two injections, symptoms improved and AEC resolved (0.0 × 109/L). Discussion Eosinophilic diseases often respond to systemic glucocorticoids, however steroid-related side-effects limit therapy and create demands for new strategies. Mepolizumab, an anti-IL-5 agent, is well-studied in hypereosinophilic syndrome clinical trials. However, its mechanism-of-action is limited to mature eosinophils. Benralizumab binds IL-5Rα, depletes peripheral eosinophils and bone marrow-resident precursor cells and reduces the AEC after one dose. In this case, we demonstrate benralizumab as a potential treatment-alternative for HE. Hypereosinophilia (HE) describes a rare and clinically-heterogeneous disease-spectrum. We present a case of a 71-year-old man with severe, unexplained HE and clinical response to benralizumab therapy. A 71-year-old man with prior history of large granular lymphocytic (LGL) leukemia (in-remission) and severe persistent asthma presented emergently with a 2-week history of fatigue, dyspnea and productive cough. He was afebrile and tachycardic with course breath sounds. The absolute eosinophil count (AEC) (6.2 × 109/L), troponin (1.24 ng/mL) and B-type natriuretic peptide (1898 pg/mL) were elevated. CT thorax demonstrated bibasilar parenchymal disease and ground-glass opacities. The patient received intravenous methylprednisolone (80 mg three-times-daily) for presumed eosinophilic myocarditis. Troponins down-trended, and AEC resolved (0.0 × 109/L) (day 3). A subsequent echocardiogram indicated no fibrosis or valvular disease. Infectious work-up, FIP1L1-PDGFRA and anti-neutrophil cytoplasmic antibodies were negative. There were no signs of LGL recurrence. The patient was discharged on prednisone, which he self-discontinued due to agitation, insomnia and increased appetite. AEC rose to 1.4 × 109/L (post-discharge-day 55) and respiratory symptoms recurred. To optimize management, the patient started benralizumab, a humanized monoclonal antibody to IL-5Rα. After two injections, symptoms improved and AEC resolved (0.0 × 109/L). Eosinophilic diseases often respond to systemic glucocorticoids, however steroid-related side-effects limit therapy and create demands for new strategies. Mepolizumab, an anti-IL-5 agent, is well-studied in hypereosinophilic syndrome clinical trials. However, its mechanism-of-action is limited to mature eosinophils. Benralizumab binds IL-5Rα, depletes peripheral eosinophils and bone marrow-resident precursor cells and reduces the AEC after one dose. In this case, we demonstrate benralizumab as a potential treatment-alternative for HE.