The Transition of Blood Biomarkers During 96-Week Treatment with Upadacitinib for Atopic Dermatitis: A Real-World Analysis Stratified by Age

<u><b><i></i></b></u> <u><b><i>Background:</i></b></u> The transition of laboratory indexes is unknown for long-term (2-year) upadacitinib treatment in atopic dermatitis (AD).<u><b><i>Objective:</i></b></u> To assess the 96-week real-world effects of upadacitinib on the transition of immunoglobulin E (IgE), thymus and activation-regulated chemokine (TARC), lactate dehydrogenase (LDH), and total eosinophil count (TEC) in Japanese patients with AD, stratified by age groups (<18, 18-64, and ≥65 years).<u><b><i>Methods:</i></b></u> In this prospective, single-center study, patients received upadacitinib 15 mg or 30 mg plus topical corticosteroids from August 2021 to November 2024. Laboratory indexes (IgE, TARC, LDH, and TEC) and clinical indexes (eczema area and severity index, peak pruritus-numerical rating scale) were measured at weeks 0, 4, 12, 24, 36, 48, 60, 72, 84, and 96.<u><b><i>Results:</i></b></u> Upadacitinib 15 and 30 mg generated a sustained reduction of clinical indexes until week 96 in all age groups. TEC decreased by week 4 or 12 and remained below baseline in all age groups. Patients aged ≥65 years maintained the lowest TEC and clinical indexes among the three age groups.<u><b><i>Conclusion:</i></b></u> Upadacitinib provided long-term reduction of TEC across all age groups in parallel with reduced clinical indexes of AD. TEC may act as a potential biomarker reflecting treatment responsiveness to upadacitinib.