Long-Term Real-World Effectiveness and Response Trajectories of Dupilumab in Paediatric Atopic Dermatitis

Background/Objectives: Long-term real-world data on dupilumab effectiveness and response trajectories in paediatric atopic dermatitis (AD) remain limited. This study evaluated long-term effectiveness, safety, response durability, and treatment trajectories in paediatric patients with moderate-to-severe AD treated with dupilumab. Methods: This retrospective single-centre cohort study included 55 paediatric patients with moderate-to-severe AD treated with dupilumab. Clinical outcomes, including Eczema Area and Severity Index (EASI), body surface area (BSA), and Children's Dermatology Life Quality Index (CDLQI), were assessed longitudinally throughout treatment. The primary endpoint was the achievement of EASI-75 over the course of treatment, including timing of response onset. Secondary endpoints included EASI-90 achievement, longitudinal changes in disease severity and quality of life, treatment durability, safety, and response trajectory analyses. Patients were additionally classified into mutually exclusive trajectory groups based on timing and durability of EASI-75 achievement. Results: Dupilumab treatment was associated with rapid and sustained clinical improvement. Some patients achieved EASI-75 as early as week 4, highlighting interindividual variability in response kinetics. At week 16, EASI-75 was achieved in 85.5% of patients and EASI-90 in 47.3%. Clinical effectiveness further improved during long-term follow-up, with EASI-75 achieved in 96.2% and EASI-90 in 86.5% of patients at the last available follow-up. Median CDLQI decreased from 22.0 at baseline to 3.0 during follow-up, indicating marked improvement in quality of life. Most patients (83.6%) were classified as early responders, while 10.9% demonstrated delayed but clinically meaningful improvement during continued treatment. Loss of response after initial EASI-75 achievement was uncommon (3.7%). Adverse events were predominantly mild, with eosinophilia and conjunctivitis representing the most frequently observed findings. Conclusions: Overall, dupilumab demonstrated high long-term effectiveness and favourable tolerability in paediatric patients with moderate-to-severe AD. Trajectory analyses revealed clinically meaningful heterogeneity in response kinetics despite favourable long-term outcomes, highlighting that delayed responders may still achieve substantial benefit during continued therapy.