Intra-class switch among interleukin-17 inhibitors for the treatment of plaque psoriasis: a single-center experience.

Psoriasis is a chronic immune-mediated disease primarily affecting the skin. The most common subtype is plaque psoriasis, which can affect any body area, with a predilection for the knees, elbows, scalp, lumbosacral region, and genitalia. The European guidelines adopted in Italy recommend systemic therapies for moderate-to-severe psoriasis, defined by a Psoriasis Area and Severity Index (PASI) ≥ 10, Dermatology Life Quality Index (DLQI) ≥ 10, and/or Body Surface Area (BSA) ≥ 10. Over the past two decades, the development of biological agents has revolutionized psoriasis management, targeting specific cytokines such as TNF-α, IL-23, and IL-17. Among these, ixekizumab, secukinumab, brodalumab, and bimekizumab are approved for the treatment of moderate-to-severe plaque psoriasis. However, some patients require switching therapy because of primary/secondary ineffectiveness or side effects. We retrospectively analyzed 20 patients who had switched from one anti-IL-17 drug to another, assessing both safety and effectiveness. 70% of patients was represented by males, with a median age of 49.5 years. The most frequent comorbidities were arterial hypertension and hypercholesterolemia. Effectiveness was evaluated in terms of a 90% (PASI90) and 100% (PASI100) reduction in PASI compared to baseline at 16 and 52 weeks. Before switching to the current IL-17 inhibitor, seven patients had failed at least two biologics. Thirteen patients experienced a loss of effectiveness after more than 6 months (secondary ineffectiveness), whereas the other seven never showed improvement with the previous drug (primary ineffectiveness). Fourteen patients completed at least one year of follow-up. Two patients were lost during the follow-up, while four more are currently still under treatment without having completed the established temporal cut-off. Two patients switched to bimekizumab, nine to brodalumab, and nine to ixekizumab. At baseline, the median PASI was 10 (IQR 4.5). After 16 weeks, the median PASI decreased to 2 (IQR 5.5), and after one year, it was 1 (IQR 2). Eight patients (40%) and six patients (30%) achieved PASI 90 and PASI 100 at 16 weeks, respectively. After one year, sustained effectiveness was observed with PASI 90 (57.1%), PASI 100 (35.7%), and PASI ≤ 2 (78.6%). No serious adverse events or discontinuations due to adverse events were observed during the study period. Our study confirms the safety and effectiveness of intraclass switching among IL-17 antagonists, highlighting that an inter-class switch can be a valid option when patients fail to respond or lose effectiveness with an IL-17 inhibitor. However, further larger and longer studies are needed for a deeper understanding.