Letter to the Editor

Outcomes after cessation of mepolizumab therapy in severe eosinophilic asthma: A 12-month follow-up analysis

The immune modulation in the epithelium is a protective feature of the epithelial function in the mucosal airways. Dysfunction of the epithelium can lead to chronic allergic airway inflammatory diseases, such as chronic rhinosinusitis with nasal polyps (CRSwNP), allergic rhinitis (AR), and allergic asthma. Chitinase-3-like-1 (CHI3L1) is a key modulator in the epithelium against irritants, pathogens, and allergens and is involved in cancers, autoimmune diseases, neurological disorders, and other chronic diseases. Induction of epithelial cell-derived CHI3L1 is also confirmed to be implicated in the pathogenesis of Th2-related airway diseases like CRSwNP, AR, and allergic asthma, triggering a cascade of subsequent inflammatory reactions leading to the disease development. The techniques that block the biological function of CHI3L1 include small interfering RNA, neutralizing antibodies, and microRNAs and these methods proved to be successful in preclinical and clinical investigation in cancers, autoimmune diseases, asthma, and chronic obstructive pulmonary disease. Therefore, treatment with CHI3L1-blocking methods could open up therapeutic options for allergic airway diseases. This review article discusses the role of epithelial cell-derived CHI3L1 in the development of CRSwNP, AR, and allergic asthma and examines the use of CHI3L1 as a potential therapeutic agent for allergic airway diseases.

Biologics have been a key component of severe asthma treatment, and there are currently biologics available that target IgE, IL-5, IL-4/IL-13, and TSLP. Randomized controlled trials have established clinical evidence, but a significant portion of patients with severe asthma in real-life settings would have been excluded from those trials. Therefore, real-world research is necessary, and there is a growing body of information about the long-term efficacy and safety of biologics.

Multiple clinical phenotypes of severe asthma exist, and it is crucial to choose patients based on their phenotypes. Blood eosinophil count is an important biomarker for anti-IL-5 therapies, and FeNO and eosinophil counts serve as prediction markers for dupilumab. Reliable markers for predicting response, however, have not yet been fully established for omalizumab. Identification of clinical or biological prediction factors is crucial for the path toward clinical remission because the current treatment goal includes clinical remission, which is defined as a realistic goal for remission off treatment.

Additionally, since there are now multiple biologic options and overlaps in eligibility for biologics in clinical practice, the evidence regarding the effectiveness of switching the biologics is crucial. Investigations into the clinical trajectory following the cessation of biologics are another important issue.

Recent research on omalizumab, mepolizumab, benralizumab and dupilumab's real-world effectiveness, the prediction factor for the efficacy, and the impact of switching or discontinuation will be reviewed and discussed in this review.

Present guidelines recommend a life-long therapy with mepolizumab in patients suffering from severe eosinophilic asthma as several studies proved the disadvantages of treatment cessation. This study evaluated the possibility of extending the dosage intervals of mepolizumab in those patients with severe eosinophilic asthma after being well controlled.

Eighteen patients diagnosed with severe eosinophilic asthma were started on treatment with mepolizumab in regular 4-week intervals. Symptom control was measured using the asthma control test (ACT) and pulmonary function test every 3 months. The amount of oral corticosteroids needed to maintain symptom control was monitored at every visit. After achieving good symptom control, defined as well controlled ACT ≥20, injection intervals were prolonged from 4 up to 6 to 8 weeks. The evaluation of this data was approved by the ethics committee.

ACT and pulmonary function values significantly improved after initiating therapy with mepolizumab on a regular 4-weekly injection interval. After extending the dosage intervals, both ACT and pulmonary function remained on a stable level without significant changes during the follow-up visits for 1 year. Median dosage of prednisolone declined significantly in the studied group under mepolizumab therapy and stayed on a low level during the follow-up visits with only a single patient using prednisolone after 1 year.

In patients with fully or well controlled eosinophilic asthma treated with mepolizumab extending the dosage intervals between the injections up to 8 weeks bears the potential to save costs for the health care system.

Eosinophils have multiple relevant biological functions, including the maintenance of homeostasis, host defense against infectious agents, innate immunity activities, immune regulation through Th1/Th2 balance, anti-inflammatory, and anti-tumorigenic effects. Eosinophils also have a main role in tissue damage through eosinophil-derived cytotoxic mediators that are involved in eosinophilic inflammation, as documented in Th2-high asthma and other eosinophilic-associated inflammatory conditions.

Recent evidence shows that these multiple and apparently conflicting functions may be attributed to the existence of different eosinophil subtypes (i.e.: tissue resident and inducible eosinophils). Therapeutic intervention with biological agents that totally deplete tissues and circulating eosinophils or, vice versa, maintain a minimal proportion of eosinophils, particularly the tissue-resident ones, could therefore have a very different impact on patients, especially when considering the administration of these therapies for prolonged time. In addition, the characterization of the predominant pathway underlying eosinophilic inflammation by surrogate biomarkers (circulating eosinophils, organ-specific eosinophils levels such as eosinophil count in sputum, bronchoalveolar lavage, tissue biopsy; total circulating IgE levels, or the use of FeNO) in the single patient with an eosinophilic-associated inflammatory condition could help in choosing the treatment.

These observations are crucial in light of the increasing therapeutic armamentarium effective in modulating eosinophilic inflammation through the inhibition in different, yet complementary ways of eosinophil pathways, such as the interleukin-5 one (with mepolizumab, benralizumab, reslizumab) or the interleukin-4/13 one (with dupilumab and lebrikizumab), in severe T2-high asthma as well as in other systemic eosinophilic associated diseases, such as eosinophilic granulomatosis with polyangiitis and hypereosinophilic syndrome.

To evaluate the efficacy and safety of anti-interleukin-5 class therapy agents in the treatment of eosinophilic asthma and the financial impact of these drugs on the Brazilian and Mato Grosso public health systems.

The literature review in important databases was guided by a structured research question including patient or population, intervention, comparator, outcome and type of study. The retrieved studies went through a screening, selection, data extraction, and methodological quality assessment process. A model with two scenarios, one with mepolizumab and the other with benralizumab, was created for budget impact analysis.

Evidence indicated that anti-interleukins-5 have an acceptable safety profile and can reduce exacerbation rates by up to 50% in the population with eosinophilic asthma; however, they showed no significant difference in quality of life. The adoption of these drugs in the Brazilian health system can impact the budget from R$ 40,379,731.50 to R$ 140,301,211.34 depending on the drug incorporated, considering a time horizon of 5 years. From the perspective of the state of Mato Grosso, the budget impact may reach, in the fifth year, an amount of R$ 1,301,210.58 and R$ 2,050.687.62 for the scenarios with mepolizumab and benralizumab, respectively.

Anti-interleukins-5 are promising treatments for eosinophilic asthma because they minimise exacerbations and are well tolerated and safe. The financial impact is large, implying that technology costs may be a barrier to accessing this treatment class.