Early treatment response to mepolizumab predicts clinical remission in severe eosinophilic asthma.

Background: Mepolizumab can induce an early response and clinical remission in people with severe eosinophilic asthma (SEA).

Objective: We questioned whether early response to mepolizumab could predict future asthma remission, and sought to identify the best predictor of treatment response to mepolizumab for achieving remission.

Methods: The Australian Mepolizumab Registry was used to investigate the early response to mepolizumab at 3 and 6 months and relate this to clinical remission at 12 months. Treatment response was assessed using the Asthma Control Questionnaire (ACQ)-5, oral corticosteroid (OCS) dose, exacerbation frequency, and post-bronchodilator FEV₁. Clinical remission, assessed at 12 months, was defined as ACQ-5 ≤1.0 at 12 months, no exacerbations in the previous 6 months, and no OCS use for asthma in the previous 6 months. We estimated the optimism-corrected area under the curve (AUC) for internal validation.

Results: We analyzed 255 participants with SEA. Seventy-eight (30.6%) participants achieved clinical remission at 12 months. A prediction model including ACQ-5 score, exacerbation frequency, OCS dose, and post-bronchodilator FEV₁ at 6 months was more predictive of achieving remission than measures at 3 months. ACQ-5 score at 6 months had the highest optimism-corrected AUC of 0.778 [95% CI: 0.719-0.833]. ACQ-5 score <1.5 at 6 months had a sensitivity of 85.9% for achieving clinical remission, while ACQ-5 score <0.75 had a specificity of 84.7%.

Conclusion: ACQ-5 score at 6 months was the best predictor of achieving clinical remission at 12 months in people with SEA treated with mepolizumab. These results can be used to design a treat-to-target paradigm for asthma, where treatment response is assessed at 6 months to predict clinical remission.