Research Summary

Anti–IL-5 Therapy Reduces Severe Exacerbations in Belgian Asthma Cohort with and without COPD

Anthony Calabro, MA

Key Highlights

  • Anti–IL-5 therapy reduced severe exacerbation rates by 56% overall.
  • Patients with asthma and coexisting COPD experienced the largest absolute reduction in hospitalizations.
  • Moderate exacerbations decreased across all subtypes except oral corticosteroid (OCS)–only events in COPD.
  • Current smoking lessened anti–IL-5 effectiveness on OCS-treated exacerbations.

Researchers in Belgium analyzed real-world data to evaluate the impact of anti–IL-5 biologic therapy—mepolizumab or benralizumab—on asthma exacerbation rates. The study, drawing on national health records, revealed reductions in both moderate and severe exacerbations after treatment initiation, irrespective of chronic obstructive pulmonary disease (COPD) comorbidity.

Adults who initiated mepolizumab or benralizumab between 2017 and 2019 were identified from Belgium’s InterMutualistic Agency and Minimal Hospital Dataset databases. Exacerbation rates (ERs) were compared in the year before and after treatment initiation. Severe exacerbations were defined as hospitalizations for asthma or COPD, while moderate events were outpatient episodes treated with antibiotics, OCS, or both. Analyses were stratified by COPD status, smoking history, and chronic OCS use. Significance was set at P < .05, and relative risk reduction (RRR) and NNT were calculated.

Study Findings

Among 807 adults (mean age 58 years, 51% female), 78% received mepolizumab and 22% received benralizumab. Overall, severe exacerbations declined from 40±4 to 17±3 per 100 patient-years (P < .001), corresponding to a 56% RRR (number needed to treat [NNT] = 4).

In patients without COPD (n = 616), the severe ER decreased from 15±2 to 6±1 (P < .001, NNT = 11). Those with coexisting COPD (n = 191) experienced the greatest absolute benefit, with ERs dropping from 119±12 to 53±9 (P < .001, NNT = 2).

Moderate exacerbations also fell significantly—from 396±9 to 281±10 per 100 patient-years (P < .001, RRR −29%, NNT = 1). Reductions were strongest for OCS-treated events (RRR −35%) compared with antibiotic-only events (RRR −19%). OCS-only exacerbations were not significantly reduced in patients with COPD (P = 0.288).

Current smoking lessened the response to anti–IL-5 therapy for OCS-treated exacerbations (NNT > 1). However, even among current smokers with COPD, hospitalizations decreased sharply—from 152±23 to 55±18 per 100 patient-years (P < .001, RRR −64%, NNT = 1). In patients dependent on OCS, OCS-treated exacerbations declined, while antibiotic-treated events rose modestly.

Clinical Implications

These findings highlight the real-world effectiveness of anti–IL-5 therapy for reducing asthma exacerbations, including among patients traditionally underrepresented in clinical trials, namely, those with COPD overlap and smokers. Reduced response among smokers for OCS-treated exacerbations indicates a need for careful management in this subgroup.

Expert Commentary

“In this nationwide cohort study, treatment targeting eosinophilic inflammation was significantly associated with reduced moderate and severe exacerbations, with seemingly less impact on corticosteroid-treated exacerbations in (current smoking) patients with coexisting COPD, but still a large number of hospitalizations were prevented,” the researchers concluded.

Reference:
Vanfleteren LEGW, Vauterin D, Lahousse L. Real-life impact of anti-IL5 therapy on exacerbation types in patients with obstructive lung disease. BMJ Open Respir Res. 2025;12(1):e003413. Published 2025 Oct 22. doi:10.1136/bmjresp-2025-003413