A 3-Year Multicentric Study on Switching from Ustekinumab to Guselkumab in Partial Responders with Psoriasis—IL PSO (Italian Landscape Psoriasis)

Introduction: Guselkumab, a human monoclonal antibody targeting the p19 subunit of interleukin-23 (IL-23), has shown efficacy in psoriasis and psoriatic arthritis. However, long-term real-world data on its effectiveness in patients with inadequate response to ustekinumab are limited. This study investigates guselkumab's long-term effectiveness and safety in patients with psoriasis with partial response to ustekinumab. Methods: We performed a retrospective multicentric study analyzing data of patients with psoriasis from seven Italian hospitals between January 2021 and May 2024. The study included 169 patients who switched from ustekinumab to guselkumab. Primary endpoints were Psoriasis Area and Severity Index (PASI) 75, PASI 90, PASI 100, and absolute PASI ≤ 2. Site-specific Physician Global Assessment (PGA) scores were also collected for difficult-to-treat areas. Results: The study included 169 patients. After 3 years of treatment, PASI 75, PASI 90 and PASI 100 were achieved by 88.4%, 55.8%, and 32.6% of patients, respectively. Site-specific PGA showed significant improvements, especially in the scalp and genital areas. After 3 years of treatment, no significant impact of higher body mass index (BMI) or cardiometabolic comorbidities on guselkumab effectiveness was detected. No severe adverse events were reported during the study period. Conclusions: In our study, guselkumab provided significant long-term effectiveness and safety in patients partially responsive to ustekinumab, improving both PASI score and site-specific PGA and confirming its potential use for patients with psoriasis switching from ustekinumab.