Abstract Rationale Eosinophils are key indicators of Type 2 inflammation in severe asthma, with blood counts providing a simple, accessible measure that often guides biologic therapy selection. Mepolizumab has demonstrated efficacy in reducing exacerbations and achieving clinical remission. However, the impact of different baseline eosinophil thresholds on long-term outcomes remains to be fully characterized. Methods TYREX is a retrospective, multicenter, real-world study of patients with severe asthma who received mepolizumab for ≥12 months to 5 years. For the present analysis, patients were stratified by baseline eosinophil count ranges (150-300 n = 33, 300-500 n = 104, ≥500 n = 245) and thresholds (≥150 n = 382, ≥300 n = 349 and ≥500 cells/μL n = 245). Outcomes assessed included annualized exacerbation rates, oral corticosteroid (OCS) use, asthma control (ACT score), lung function, and clinical remission, defined as no exacerbations, no OCS use, ACT ≥20, and stabilized lung function (FEV1 ≥80%). Analyses were performed at 12 months and at the end of follow-up. Results A total of 446 patients with severe asthma treated with mepolizumab were included in the TYREX study, with a mean treatment duration of 49.08 months (SD: 24.84; median: 47.76 months). At 12 months and the end of follow-up, annualized exacerbation rates decreased significantly across all eosinophil count subgroups, with no significant differences between them. The proportion of patients achieving ACT ≥20 exceeded 80% in all subgroups. Daily oral corticosteroid uses also declined markedly across all groups, with no significant differences among them. FEV₁ improved across all subgroups and both periods, with the greatest gains in patients with eosinophils ≥500 cells/μL. This variable (at both 12 months and end of follow-up) showed significant differences in baseline eosinophil ranges (p = 0.0401 and 0.0069, respectively). Clinical remission was achieved by approximately one-third of patients at 12 months and remained stable over time, with no clinically relevant differences between subgroups (Table 1). Conclusion Mepolizumab provided sustained improvements in exacerbation rates, asthma control, OCS use, and clinical remission, with sustained benefits throughout the follow-up period across a range of baseline eosinophil levels (≥150 cells/µL). These findings highlight the consistent and sustained clinical benefits of mepolizumab in patients with severe asthma, irrespective of baseline eosinophil thresholds. This abstract is funded by: GSK Spain S.A.
Perez-De-Llano et al. (Fri,) studied this question.