嗜酸性白血球增多症 (hypereosinophilic syndrome, HES) 是一種嗜酸性白血球持續過量產生，且因嗜酸性白血球浸潤引起器官損傷或功能障礙的血液疾病。此疾病過去被認為是原發性或不明原因所引起，隨著診斷方式的進展，目前已可確認部分病因。臨床症狀會因侵犯部位不同而有差異，可能會影響任何器官系統，其中又以皮膚、呼吸道（肺部）、腸胃道、心臟、中樞神經系統等最常受到影響。傳統治療的藥物包含：皮質類固醇、細胞毒性藥物以及免疫調節劑。近年發展了許多新的治療藥物，如：酪胺酸激酶抑制劑、單株抗體等，直接針對嗜酸性白血球作用，提供更有效且藥物副作用更低的選擇。Mepolizumab (Nucala®) 是第一個也是目前唯一被核准用於治療HES 的interleukin 5 (IL-5) 單株抗體，藉由與IL-5 結合，防止IL-5 與嗜酸性白血球上IL-5 受體的α 鏈結合，抑制IL-5 調控的下游訊息傳遞，使體內嗜酸性白血球的濃度降回並維持在正常值，減少臨床症狀的惡化。2020年9月美國食品藥物管理局 (United States Food and Drug Administration, FDA) 核准用於治療12 歲以上兒童及成人，患有HES 且症狀持續6 個月以上且無其他非血液學相關病因者。透過綜合性的探討及案例介紹，希望能提供臨床醫療人員診斷及治療的方向，讓病患有更多且更適合的治療選擇。
Hypereosinophilic syndromes (HES) are blood disorders characterized by the sustained overproduction of eosinophils and organ damage or dysfunction caused by eosinophil infiltration. HES was previously considered to be idiopathic or of unknown origin, but with advancements in diagnostic methods, certain underlying causes can now be identified. Clinical symptoms vary depending on the affected organs, and HES can affect multiple organ systems, with the skin, respiratory tract (lungs), gastrointestinal tract, heart, and central nervous system being the most commonly affected. Traditional treatment options for HES include corticosteroids, cytotoxic drugs, and immunomodulatory agents. In recent years, several new therapeutic agents have been developed, such as tyrosine kinase inhibitors and monoclonal antibodies, which directly target eosinophils and provide more effective and less side-effectprone choices. Mepolizumab (Nucala®) is the first and currently the only approved monoclonal antibody targeting interleukin 5 (IL-5) for the treatment of HES. By binding to IL-5 and preventing its interaction with the alpha chain of IL-5 receptors on eosinophils, mepolizumab inhibits downstream signaling regulated by IL-5, reducing the concentration of eosinophils in the body and maintaining it within normal levels, thus alleviating clinical symptoms. In September 2020, the United States Food and Drug Administration approved mepolizumab for the treatment of HES in children aged 12 and above and adults, who have had the condition for at least 6 months without any identifiable non-hematologic causes. Through comprehensive discussions and case presentations, we aim to provide clinical healthcare professionals with diagnostic and treatment directions, offering patients more and appropriate treatment options.
Submitted for publication: 2022.3.10; Accepted for publication: 2023.3.1
