Ixekizumab Effectiveness and Safety in the Treatment of Moderate-to-Severe Plaque Psoriasis: A Multicenter, Retrospective Observational Study

Background: Ixekizumab (anti-IL-17A) is a biological agent used for the treatment of moderate-to-severe psoriasis. Real-life data on the effectiveness and safety of ixekizumab are currently scarce. Objective: The objective of this study was to evaluate the effectiveness and safety of ixekizumab in a cohort of psoriatic and psoriatic arthritis patients. Methods: We conducted a retrospective study involving 201 patients affected by moderate-to-severe psoriasis and treated with ixekizumab at seven Italian University centers. Data analysis focused on 110 patients who started ixekizumab at baseline and completed at least 24 weeks of treatment. Results: Significant reduction of mean (± standard deviation) baseline Psoriasis Area Severity Index (PASI) score (14.3 ± 5.8) was detected at 4 weeks of ixekizumab therapy (4.9 ± 4.2, p < 0.001), with a further significant improvement at weeks 12 and 24 (1.9 ± 2.9 and 0.9 ± 1.6, respectively) (p < 0.001). Our analysis showed 90%, 72%, and 57% of patients achieving PASI 75, 90, and 100 responses (75%, 90%, and 100% reduction in PASI score), respectively, after 24 weeks’ therapy. For patients with arthritis (28%), a significant reduction in the mean (± standard deviation) baseline Disease Activity Score (DAS)-28 score (4.6 ± 5.1) was detected at week 4 (2.5 ± 3.9, p < 0.01), with a further significant improvement at weeks 12 and 24 (2.1 ± 1.2 and 1.4 ± 0.9, respectively) (p < 0.001). The bio-naïve group showed significantly higher PASI 90 and 100 response rates at week 12 than the bio-exposed one (p < 0.05). This trend in terms of PASI 100 response was also maintained at week 24 (p < 0.05). Furthermore, PASI 90 responses were significantly higher in anti-interleukin (IL)-17A-naïve patients at week 24 than in anti-IL-17A-experienced ones (p < 0.05). The dropout rate for adverse events (AEs) was as low as 2% (2/110), while AEs that did not cause treatment interruption were observed in 6% (7/110). Patients withdrawing from the study were defined as non-responders according to the non-responder imputation method. The retrospective design of the study does not allow missing data to be retrieved or homogeneous patient selection. Conclusions: The present study illustrates ixekizumab in real-world clinical practice, confirming its usefulness and safety in the management of psoriasis and psoriatic arthritis.