Anti-IL-5 therapy in patients with severe eosinophilic asthma - clinical efficacy and possible criteria for treatment response

Abstract

Background: Interleukin-5 (IL-5) antibodies represent a promising therapeutic option for patients with severe eosinophilic asthma. To date, no official treatment response criteria exist. In this study, simple criteria for treatment response applicable to all asthma patients were used to evaluate clinical efficacy and predictors for treatment response in a real-life setting.

Methods: Data from 42 patients with severe eosinophilic asthma treated with mepolizumab for at least six months were analysed. Simple criteria to assess treatment response in clinical practice were used: increase of FEV₁ ≥ 12% or ≥ 200 ml, reduction of blood eosinophils (< 150/μl or < 80% from baseline) and improvement of subjective condition (patient-judged subjective improvement or worsening following therapy). Patients were considered treatment responders if two criteria were fulfilled.

Results: Thirty-two out of 42 patients (76% [61-87%]) were classified as responders. Within the groups (responder vs non-responder), treatment with mepolizumab led to significant increase in FEV₁ (+ 600 ml vs -100 ml, p = 0.003), oxygenation (+ 8 mmHg vs -3 mmHg, p = 0.001), quality of life (visual analogue scale; + 28% vs - 5%, p = 0.004) and Asthma Control Test (+ 8 vs + 1 points, p = 0.002). In the responder group a significant decrease in the exacerbation rate over 12 months (1.45 vs 0.45, p = 0.002) was observed. Baseline characteristics (sex, BMI, smoking history, allergies, baseline level of eosinophils) did not predict treatment response.

Conclusion: Using improvement of lung function, decrease of eosinophils and improvement of subjective condition as response criteria, 76% of treated patients could be classified as treatment responders, demonstrating the efficacy of anti-IL-5 therapy in clinical practice.

Keywords: IL-5; Lung function; Mepolizumab; Severe eosinophilic asthma; Treatment response.

Fig. 1

Follow-up after anti-IL-5 therapy initiation. FEV₁ (forced expiratory volume in one second)

Fig. 2

Comparison of the change (delta) from baseline to follow-up visit of lung function, blood eosinophils, capillary oxygenation, quality of life and asthma control test between both groups (responder vs non-responder). Percentages are stated as % of predicted. a FEV₁, forced expiratory volume in one second; b RV residual volume; c Eos eosinophils; d QoL quality of life, VAS visual analogue scale; e pO2 partial pressure of oxygen; f ACT asthma control test

Fig. 3

Analysis of potential predictors for treatment response. BMI, body mass index; FEV₁, forced expiratory volume in one second