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, including tumor necrosis factor (TNF)-α, interleukin (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. At baseline, the median PASI score was 10 (interquartile range [IQR] 4.5). After 16 weeks, it decreased to 2 (IQR 5.5), and after one year, it decreased further to 1 (IQR 2). Eight (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 (AEs) or discontinuations due to AEs were observed during the study period. Our study confirms the safety and effectiveness of intra-class switching among IL-17 antagonists within the same class and highlights that switching between different classes of IL-17 inhibitors can be a valid option when patients fail to respond or lose effectiveness with a particular inhibitor. However, a deeper understanding requires further large-scale and long-term studies.