Real-life responder studies to anti-IL5/IL5(R) therapy suggest markers of good asthma control as predictors of response, sometimes more so than indicators for type 2 inflammation identified as essential predictors in RCTs.

We aimed to elucidate baseline markers of response to anti-IL5/IL5(R) therapy, defined as reduction of ?50% in exacerbation rate or corticosteroid dose, in patients with severe asthma from the German Asthma Net (GAN), a real-life, multi-centre registry.

We evaluated 346 patients (55% female, 57±12 years, 4.7±4.8 exacerbations/year, 5.9±11.4 mg prednisolone equivalent dose) with follow-ups of at least 1, and at most 7 years (mean 20.3±13 months), and found that 78% of patients were responders to anti-IL5/IL5(R) therapy.

Responders under anti-IL5/IL(R) therapy were defined at baseline by significantly higher blood eosinophil numbers (p=0.015), corticosteroid dependence (p=0.007), and exacerbation rates (p=0.001). An increase of blood eosinophil number by 1000/µL increased the odds of being a responder by 6.1 times (95%CI: 1.7; 30.8). Similarly, for every exacerbation per year experienced, the odds of responding well to anti-IL5 therapy increased by 1.18 (95%CI: 1.1; 1.4), and for each mg of corticosteroid dose by 1.11 (95%CI: 1.1; 1.2).

In conclusion, responders to anti-IL5/IL5(R) in this large, comprehensively studied, well-characterized long-term cohort of patients with severe asthma had more blood eosinophils, higher maintenance corticosteroid doses, and exacerbation rates at baseline. Importantly, this underscores that anti-IL5 therapy improves essential outcomes such as exacerbations and corticosteroid burden especially in patients with a high inflammatory and disease burden.