question: BACKGROUND Primary (week 16) results from the ongoing phase 3, double-blind AD Up study (NCT03568318) demonstrate a positive benefit-risk profile for upadacitinib+TCS in patients with moderate-to-severe AD. OBJECTIVE Evaluate efficacy and safety of UPA+TCS through 52 weeks. METHODS Patients (12-75y) with chronic AD (≥10% of body surface area affected, EASI ≥16, vIGA-AD™ ≥3, and WP-NRS score ≥4) were randomized 1:1:1 to once-daily upadacitinib 15mg+TCS, upadacitinib 30mg+TCS, or PBO+TCS (re-randomized at week 16 to upadacitinib+TCS). Safety and efficacy, including proportion of patients achieving ≥75% improvement in EASI (EASI-75), vIGA-AD of clear/almost clear with improvement ≥2 grades (vIGA-AD 0/1), and WP-NRS improvement ≥4, were assessed through week 52. Missing data were primarily handled by nonresponder imputation incorporating multiple imputation for missing values due to COVID-19. RESULTS Of 901 patients, 300 were randomized to upadacitinib 15mg+TCS, 297 to upadacitinib 30mg+TCS, and 304 to PBO+TCS. For all endpoints, efficacy for upadacitinib 15mg+TCS and upadacitinib 30mg+TCS at week 16 was maintained through week 52. At week 52, the proportions of patients treated with upadacitinib 15mg+TCS and upadacitinib 30mg+TCS who achieved EASI-75 were 50.8% and 69.0%, respectively; 33.5% and 45.2%, respectively, achieved vIGA-AD 0/1; and 45.3% and 57.5%, respectively, achieved WP-NRS improvement ≥4. upadacitinib+TCS was well tolerated through 52 weeks; no new important safety risks beyond the current label were observed. No deaths were reported; events of MACE and VTE were infrequent (≤0.2/100 PY). CONCLUSION Results through 52 weeks demonstrate long-term maintenance of efficacy and a favorable safety profile of upadacitinib+TCS in patients with moderate-to-severe AD.