Mepolizumab Benefits Severe Asthma Across BEC, IgE, FeNO Levels in Real-World Data

Mark Liu, MD

Credit: Johns Hopkins Medicine

Mepolizumab reduced clinically significant exacerbations (CSE) in people with severe asthma (SA) across blood eosinophil count (BEC) levels in real-world data.¹

These findings, from the REALITI-A study, were presented at the 2025 American Academy of Allergy, Asthma, and Immunology (AAAAI)/World Allergy Organization (WAO) Joint Congress, February 28-March 3, in San Diego, California, by Mark Liu, MD, Professor of Medicine, Johns Hopkins Medicine.

“Real-world effectiveness of mepolizumab was confirmed at 1 year in patients with SA and sustained across all baseline BEC subgroups, with reductions in CSEs at 2 years post exposure,” Liu and colleagues wrote.¹

The study stratified participants into groups of <150, ≥150−<300, ≥300−<500, ≥500 BEC cells/µL. This analysis included 822 participants. Liu and colleagues found that rates of CSEs reduced from those observed during the 1-year pre-exposure period across all BEC subgroups at 2 years post‑mepolizumab exposure.¹

Specifically, the 98 participants in the <150 group had a rate ratio of 0.32 (95% CI, 0.25-0.42), the 83 participants in the ≥150−<300 group had a rate ratio of 0.32 (95% CI, 0.25-0.41), the 154 participants in the ≥300−<500 group had a rate ratio of 0.29 (95% CI, 0.24-0.36), the 277 participants in the ≥500 group had a rate ratio of 0.22 (95 CI%, 0.18-0.26).¹

The investigators also found that post- versus pre-mepolizumab exposure was associated with increased odds of zero CSEs at 2 years, across BEC subgroups, with the <150 group having an odds ratio (OR) of 7.11 (95% CI, 3.60-14.06), the ≥150−<300 group having an OR of 11.92 (95% CI, 4.07-34.90), the ≥300−<500 group having an OR of 5.88 (95% CI, 3.22-10.72), and the ≥500 group having an OR of 22.65 (95% CI, 12.41-41.33).¹

“Reductions in CSEs observed at 1 year post exposure compared with the pre-exposure period were maintained after 2 years, demonstrating real-world sustained benefit with mepolizumab,” Liu and colleagues wrote.¹ “Compared with the pre-exposure period, mepolizumab treatment resulted in increased odds of zero CSEs observed at 2 years post exposure.”

Another analysis of REALITI-A, presented by Jason Lee, MD, Clinical Immunology and Allergy and Internal Medicine, Toronto Allergists, found similar CSE reductions across IgE and FeNO levels at baseline.²

Specifically, the 173 participants in the tIgE<60 kU/L group had a rate ratio of 0.28 (95% CI, 0.23-0.34), the 161 participants in the tIgE≥60–<180 kU/L group had a rate ratio of 0.28 (95% CI, 0.23-0.34), the 174 participants in the tIgE≥180–<500 kU/L group had a rate ratio of 0.23 (95% CI, 0.18-0.29), and the 166 participants in the tIgE≥500 kU/L group had a rate ratio of 0.28 (95% CI, 0.22-0.34).²

The investigators also found that improvements observed at 1 year post-exposure were sustained, with the tIgE<60 kU/L group having a rate ratio of 0.31 (95% CI, 0.25-0.37), the tIgE≥60–<180 kU/L group having a rate ratio of 0.31 (95% CI, 0.25-0.37), the tIgE≥180–<500 kU/L group having a rate ratio of 0.25 (95% CI, 0.19-0.31), and the tIgE≥500 kU/L group having a rate ratio of 0.30 (95% CI, 0.24-0.37).²

Regarding FeNO levels, the <25 ppb group had a rate ratio of 0.26 (95% CI, 0.21-0.33), the ≥25–<50 ppb group had a rate ratio of 0.27 (95% CI, 0.21-0.36), and the ≥50 ppb group had a rate ratio of 0.28 (95% CI, 0.23-0.35), with sustained improvements at 1 year post-exposure (rate ratios: 0.29 [95% CI, 0.23-0.36], 0.28 [95% CI, 0.21-0.37], and 0.30 [95% CI, 0.24-0.38], respectively).²

REFERENCES

1. Liu M, Gould S, Noorduyn S, et al. Mepolizumab Improves and Sustains Clinical Benefits in Patients With Severe Asthma, Independent of Blood Eosinophil Count at Baseline: Real-World Analysis of REALITI-A Results at 2 Years. Presented at: 2025 AAAAI/WAO Joint Congress, February 28-March 3. Abstract 712

2. Lee J, Liu M, Gould S, et al. Mepolizumab Improves and Sustains Clinical Benefits in Patients With Severe Asthma, Independent of IgE and FeNO at Baseline: Real-World Analysis of REALITI-A Results at 2 Years. Presented at: 2025 AAAAI/WAO Joint Congress, February 28-March 3. Abstract 722.