Determining early response to anti-IL5/IL5R monoclonal antibodies in severe eosinophilic asthma

Anti-IL5/IL5R therapies are widely used for treating severe eosinophilic asthma (SEA). At present there is no consensus on when to determine a response to these drugs. Given the expanding therapeutic options, it is important for clinicians to make a prompt decision about continuation of therapy. Methods: We conducted a retrospective review of patients who had completed at least a year of mepolizumab or benralizumab treatment. Patients were categorized as responders or non-responders at weeks 16, 24 and 52. Response was defined as ≥50% reduction in either maintenance oral corticosteroid (mOCS) or annualised exacerbation rate. Results: 163 patients were included in the analysis (mean age 52.8, 59% female), 99 patients received mepolizumab and 64 received benralizumab. Responder status was accurately determined in 134 (82%) of patients at 16 weeks (sensitivity 84%, specificity 78%) and 144 (88%) at 24 weeks (sensitivity 90%, specificity 82%). Conclusion: In a large real-world cohort of anti-IL-5/5R patients it is possible to accurately determine responder status as early as 16 weeks with sensitivity rates rising to ~90% at 24 weeks. Further research including post-hoc analyses of the phase 3 studies in SEA would be helpful in further validating these findings.