A Case of Hypereosinophilic Syndrome After Mepolizumab Treatment

The following case study was authored by K Jackson, S Bahna and D Kaufman, and presented at the American College of Asthma, Allergy and Immunology (ACAAI) annual meeting in Seattle, Washington.

Introduction: Little is known about potential consequences of stopping mepolizumab therapy in asthmatic patients. This is a case of a 43-year-old female diagnosed with eosinophilic myocarditis six months after cessation of mepolizumab.

Case Description: A 43-year-old female with severe eosinophilic asthma was started on mepolizumab. She remained compliant for 2 year with significant improvement of symptoms but due to a lapse of insurance coverage, therapy was interrupted. Six months later, she developed low grade fever, cough, and dyspnea with infiltrates on CXR. She was diagnosed with atypical pneumonia and treated with antibiotics without improvement. Within a few days, she developed hypoxic respiratory failure requiring noninvasive ventilation support. WBC was 26.2 K/uL with eosinophilia of 9.69 K/uL. She had elevated troponin (7.58); EKG had lateral ST elevation myocardial infarction, and echocardiogram showed pericardial effusion with EF of 20-25%. Infectious workup was unremarkable. Heart catheterization revealed normal coronaries. Pericardiocentesis cytology demonstrated 89% eosinophils. Cardiac MRI showed circumferential subendocardial hyperenhancement of left ventricle and global ventricular hypokinesis. Bone marrow biopsy and cytogenetic testing were negative. She was diagnosed with eosinophilic myocarditis and started on IV methylprednisolone with marked improvement in symptoms. The patient was discharged on high dose prednisone and heart failure therapy. Three months later, she resumed mepolizumab and has been tolerating a slow prednisone taper.

Discussion: To our best knowledge, this is the first reported case of eosinophilic myocarditis and pneumonia after mepolizumab cessation. This patient may have had a rebound hypereosinophilia or an underlying hypereosinophilic syndrome which was masked by

mepolizumab therapy.

In one practitioner's experience, adding mepolizumab to the treatment regimens of patients with severe eosinophilic asthma in his practice resulted in improved symptoms and quality of life, similar to those reported in controlled clinical trials with screened participants.

"After extensive double-blind controlled studies, it is always reassuring to the physician in the field that the results of these studies are applicable in a private practice office setting," Ronald Strauss, MD, Cleveland Allergy & Asthma Center and Case Western Reserve University Medical School, Cleveland, Ohio, told MD Magazine®.

Moreover, data from the longest anti-interleukin 5 (IL-5) biologic therapy trial in severe eosinophilic asthma ever reported found that mepolizumab consistently improved exacerbation reduction and asthma control in patients with the condition.

Data from the open-label COLUMBA study, presented at the 2018 American Thoracic Society (ATS) International Conference in San Diego, CA, reported the results of patients with severe eosinophilic asthma who were treated with mepolizumab for a mean 3.5 years and up to 4.5 years. Along with consistent clinical efficacy, patients treated with the drug reported safety profiles similar with previous studies.