Background Eosinophilic inflammation, which may be a consequence of interleukin-5 action, is a characteristic feature of some forms of asthma. However, in three previous clinical trials involving patients with asthma, blockade of this cytokine did not result in a significant improvement in outcomes. We studied the prednisone-sparing effect of mepolizumab, a monoclonal antibody against interleukin-5, in a rare subgroup of patients who have sputum eosinophilia and airway symptoms despite continued treatment with prednisone. Secondary objectives were to examine its effect on the number of eosinophils in sputum and blood, symptoms, and airflow limitation. Methods In this randomized, double-blind, parallel-group trial involving patients with persistent sputum eosinophilia and symptoms despite prednisone treatment, we assigned 9 patients to receive mepolizumab (administered in five monthly infusions of 750 mg each) and 11 patients to receive placebo. Results There were 12 asthma exacerbations in 10 patients who...

https://www.nejm.org/doi/pdf/10.1056/NEJMoa0805435

Mepolizumab for Prednisone-Dependent Asthma with Sputum Eosinophilia

The discovery of cytokines as key drivers of immune-mediated diseases has spurred efforts to target their associated signalling pathways. Janus kinases (JAKs) are essential signalling mediators downstream of many pro-inflammatory cytokines, and small-molecule inhibitors of JAKs (jakinibs) have gained traction as safe and efficacious options for the treatment of inflammation-driven pathologies such as rheumatoid arthritis, psoriasis and inflammatory bowel disease. Building on the clinical success of first-generation jakinibs, second-generation compounds that claim to be more selective are currently undergoing development and proceeding to clinical trials. However, important questions remain about the advantages and limitations of improved JAK selectivity, optimal routes and dosing regimens and how best to identify patients who will benefit from jakinibs. This Review discusses the biology of jakinibs from a translational perspective, focusing on recent insights from clinical trials, the development of novel agents and the use of jakinibs in a spectrum of immune and inflammatory diseases.

JAK inhibition as a therapeutic strategy for immune and inflammatory diseases.

Eosinophils have been traditionally perceived as terminally differentiated cytotoxic effector cells. Recent studies have profoundly altered this simplistic view of eosinophils and their function. New insights into the molecular pathways that control the development, trafficking and degranulation of eosinophils have improved our understanding of the immunomodulatory functions of these cells and their roles in promoting homeostasis. Likewise, recent developments have generated a more sophisticated view of how eosinophils contribute to the pathogenesis of different diseases, including asthma and primary hypereosinophilic syndromes, and have also provided us with a more complete appreciation of the activities of these cells during parasitic infection.

Eosinophils: changing perspectives in health and disease

Advancing our understanding of mechanisms of immune regulation in allergy, asthma, autoimmune diseases, tumor development, organ transplantation, and chronic infections could lead to effective and targeted therapies. Subsets of immune and inflammatory cells interact via ILs and IFNs; reciprocal regulation and counter balance among T(h) and regulatory T cells, as well as subsets of B cells, offer opportunities for immune interventions. Here, we review current knowledge about ILs 1 to 37 and IFN-γ. Our understanding of the effects of ILs has greatly increased since the discoveries of monocyte IL (called IL-1) and lymphocyte IL (called IL-2); more than 40 cytokines are now designated as ILs. Studies of transgenic or knockout mice with altered expression of these cytokines or their receptors and analyses of mutations and polymorphisms in human genes that encode these products have provided important information about IL and IFN functions. We discuss their signaling pathways, cellular sources, targets, roles in immune regulation and cellular networks, roles in allergy and asthma, and roles in defense against infections.

https://www.jacionline.org/article/S0091-6749(10)01949-4/pdf

Interleukins, from 1 to 37, and interferon-γ: receptors, functions, and roles in diseases

BackgroundEosinophilic granulomatosis with polyangiitis is an eosinophilic vasculitis Mepolizumab, an anti–interleukin-5 monoclonal antibody, reduces blood eosinophil counts and may have value in the treatment of eosinophilic granulomatosis with polyangiitis MethodsIn this multicenter, double-blind, parallel-group, phase 3 trial, we randomly assigned participants with relapsing or refractory eosinophilic granulomatosis with polyangiitis who had received treatment for at least 4 weeks and were taking a stable prednisolone or prednisone dose to receive 300 mg of mepolizumab or placebo, administered subcutaneously every 4 weeks, plus standard care, for 52 weeks The two primary end points were the accrued weeks of remission over a 52-week period, according to categorical quantification, and the proportion of participants in remission at both week 36 and week 48 Secondary end points included the time to first relapse and the average daily glucocorticoid dose (during weeks 48 through 52) The annualized rel

/pdf/mepolizumab-or-placebo-for-eosinophilic-granulomatosis-with-4g48l2jo19.pdf

Mepolizumab or Placebo for Eosinophilic Granulomatosis with Polyangiitis

The primary end point was reached in 84% of patients in the mepolizumab group, as compared with 43% of patients in the placebo group (hazard ratio, 2.90; 95% confidence interval [CI], 1.59 to 5.26; P<0.001) with no increase in clinical activity of the hypereosinophilic syndrome. A blood eosinophil count of less than 600 per microliter for 8 or more consecutive weeks was achieved in 95% of patients receiving mepolizumab, as compared with 45% of patients receiving placebo (hazard ratio, 3.53; 95% CI, 1.94 to 6.45; P<0.001). Serious adverse events occurred in seven patients receiving mepolizumab (14 events, including one death; mean [±SD] duration of exposure, 6.7±1.9 months) and in five patients receiving placebo (7 events; mean duration of exposure, 4.3±2.6 months). CONCLUSIONS Our study shows that treatment with mepolizumab, an agent designed to target eosinophils, can result in corticosteroid-sparing for patients negative for FIP1L1– PDGFRA who have the hypereosinophilic syndrome. (ClinicalTrials.gov number, NCT00086658.)

/pdf/treatment-of-patients-with-the-hypereosinophilic-syndrome-147mgeob9w.pdf

Treatment of patients with the hypereosinophilic syndrome with mepolizumab

Background Hypereosinophilic syndrome (HES) is a heterogeneous group of rare disorders defined by persistent blood eosinophilia ≥1.5 × 10 9 /L, absence of a secondary cause, and evidence of eosinophil-associated pathology. With the exception of a recent multicenter trial of mepolizumab (anti–IL-5 mAb), published therapeutic experience has been restricted to case reports and small case series. Objective The purpose of the study was to collect and summarize baseline demographic, clinical, and laboratory characteristics in a large, diverse cohort of patients with HES and to review responses to treatment with conventional and novel therapies. Methods Clinical and laboratory data from 188 patients with HES, seen between January 2001 and December 2006 at 11 institutions in the United States and Europe, were collected retrospectively by chart review. Results Eighteen of 161 patients (11%) tested were Fip1-like 1–platelet-derived growth factor receptor α ( FIP1L1-PDGFRA ) mutation—positive, and 29 of 168 patients tested (17%) had a demonstrable aberrant or clonal T-cell population. Corticosteroid monotherapy induced complete or partial responses at 1 month in 85% (120/141) of patients with most remaining on maintenance doses (median, 10 mg prednisone equivalent daily for 2 months to 20 years). Hydroxyurea and IFN-α (used in 64 and 46 patients, respectively) were also effective, but their use was limited by toxicity. Imatinib (used in 68 patients) was more effective in patients with the FIP1L1-PDGFRA mutation (88%) than in those without (23%; P Conclusion This study, the largest clinical analysis of patients with HES to date, not only provides useful information for clinicians but also should stimulate prospective trials to optimize treatment of HES.

/pdf/hypereosinophilic-syndrome-a-multicenter-retrospective-1lr6qbuyih.pdf

Hypereosinophilic syndrome: a multicenter, retrospective analysis of clinical characteristics and response to therapy.

Background Hypereosinophilic syndromes (HESs) are chronic disorders that require long-term therapy to suppress eosinophilia and clinical manifestations. Corticosteroids are usually effective, yet many patients become corticosteroid refractory or develop corticosteroid toxicity. Mepolizumab, a humanized monoclonal anti-IL-5 antibody, showed corticosteroid-sparing effects in a double-blind, placebo-controlled study of FIP1L1/PDGFRA -negative, corticosteroid-responsive subjects with HESs. Objective We evaluated long-term safety and efficacy of mepolizumab (750 mg) in HES. Methods MHE100901 is an open-label extension study. The primary end point was the frequency of adverse events (AEs). Optimal dosing frequency, corticosteroid-sparing effect of mepolizumab, and development of antimepolizumab antibodies were also explored. Results Seventy-eight subjects received 1 to 66 mepolizumab infusions each (including mepolizumab infusions received in the placebo-controlled trial). Mean exposure was 251 weeks (range, 4-302 weeks). The most common dosing interval was 9 to 12 weeks. The incidence of AEs was 932 events per 100 subject-years in the first year, declining to 461 events per 100 subject-years after 48 months. Serious AEs, including 1 death, were reported by the investigator as possibly due to mepolizumab in 3 subjects. The median daily prednisone dose decreased from 20.0 to 0 mg in the first 24 weeks. The median average daily dose for all subjects over the course of the study was 1.8 mg. Sixty-two percent of subjects were prednisone free without other HES medications for ≥12 consecutive weeks. No neutralizing antibodies were detected. Twenty-four subjects withdrew before study completion for death (n = 4), lack of efficacy (n = 6), or other reasons. Conclusion Mepolizumab was well tolerated and effective as a long-term corticosteroid-sparing agent in PDGFRA -negative HES.

/pdf/long-term-safety-of-mepolizumab-for-the-treatment-of-1v31ykok22.pdf

Jean Emmanuel Kahn

Papers

Treatment of patients with the hypereosinophilic syndrome with mepolizumab

Hypereosinophilic syndrome: a multicenter, retrospective analysis of clinical characteristics and response to therapy.

Long-term safety of mepolizumab for the treatment of hypereosinophilic syndromes