Background: Biologics targeting immunoglobulin E, interleukin (IL)-4/IL-13 or IL-5 signaling are effective at treating severe asthma; however, individual patients' responses may be suboptimal, leading to therapy switching or stopping. The CLEAR study aimed to assess real-world biologic use patterns and associated clinical outcomes in patients receiving care for severe asthma.
Methods: CLEAR was a multicenter, observational study that included adults (≥18 years old) from 23 countries enrolled in the International Severe Asthma Registry between December 2015 and August 2021. Patients who initiated biologic therapy were categorized as continuing the initial biologic for 6 months, switching to another biologic within 6 months or stopping biologic treatment within 6 months. Outcomes were assessed using the closest available data to 12 months after biologic initiation, using propensity score-weighted multivariable regression models.
Results: Among 1,859 patients who initiated biologic therapy, 1,116 (60.0%) continued, 474 (25.5%) switched and 269 (14.5%) stopped treatment. Patients who switched or stopped therapy had a higher annualized asthma exacerbation rate post-initiation than those who continued (adjusted incidence rate ratio [aIRR] [95% confidence interval]: switched, 1.83 [1.51, 2.22]; stopped, 1.53 [1.19, 1.95]) and were more likely to have uncontrolled asthma at last assessment (adjusted odds ratio: switched, 5.40 [3.12, 9.33]; stopped, 4.02 [2.32, 6.98]). Compared with those who continued therapy, patients who switched had a higher long-term daily oral corticosteroid dose (adjusted β: 3.77 [1.71, 4.37] mg) and higher rates of hospitalizations (aIRR: 2.58 [1.52, 4.37]) and emergency room visits (aIRR: 2.12 [1.39, 3.24]).
Conclusion: Switching or stopping biologic therapy was associated with worse clinical outcomes than continuing the initial therapy.
Keywords: ISAR; biologics; effectiveness; real-world; severe asthma.
© 2025 Tran et al.