Intraclass Switching of IL-23 Inhibitors in Psoriasis: Effectiveness, Patterns, and Predictors of Response - A Retrospective Multicenter Study in Italy

Background: IL-23 inhibitors are highly effective therapies for psoriasis, but some patients may need to discontinue the treatment. Intraclass switching is a potential strategy, though data on its effectiveness remain limited. Objective: To evaluate the patterns and effectiveness of intraclass switching among IL-23 inhibitors in a real world setting. Methods: This retrospective, multicenter study included adult patients with plaque psoriasis who switched between IL-23 inhibitors. Clinical and demographic data were analyzed, and univariable and multivariable analyses identified predictors of treatment response. Results: We analyzed 116 patients (120 switches). Switching occurred from guselkumab (45.0%), tildrakizumab (44.2%), and risankizumab (10.8%), mainly due to secondary ineffectiveness (82.5%). Risankizumab was the most common post-switch agent (70.0%), followed by guselkumab (23.3%) and tildrakizumab (6.7%). PASI90 rates were 28.5% at week 16, 49.5% at week 36, and 60.7% at week 52. Withdrawal occurred in 12.5% of cases, mainly due to lack of efficacy (66.7%) or adverse events (26.7%). Univariate analysis showed lower PASI90 achievement in PsA patients at weeks 16 after the switch (p = 0.0209) and 36 (p = 0.026) and in those with BMI ≥25 at week 52 (p = 0.0108). Patients switching from risankizumab had lower PASI90 rates at weeks 16 (p = 0.0489) and 36 (p = 0.0349), while those switching to risankizumab had higher PASI90 rates at week 16 (p = 0.0257). Multivariate analysis confirmed BMI >25 was associated with reduced PASI90 at weeks 36 (p = 0.0403) and 52 (p = 0.0462). Conclusions: Intraclass switching among IL-23 inhibitors is an effective strategy, with risankizumab emerging as the most favorable option.