Objective: To assess the clinical response to ixekizumab following secukinumab failure in patients with psoriatic arthritis. Methods: A retrospective multi-center observational study included psoriatic arthritis (PsA) patients with a history of treatment with secukinumab, further treated with ixekizumab. Primary endpoint was primary response to treatment (drug survival > 6 months); secondary endpoints were changes in disease activity indices from initiation of ixekizumab to 6 and 12 months later and overall drug survival. Results: Of 23 PsA patients, 86% (n = 20) received more than two TNF inhibitors (TNFi). Median secukinumab treatment time was 15 months (IQR 10-21.5 months). Subsequently, 19 patients (83%) had a primary response to ixekizumab. Overall treatment duration during follow-up period for primary responders was 14 months (IQR 10-20.5). Reasons for ixekizumab cessation were worsening psoriasis (27%), peripheral arthritis (27%), both (47%), worsening of axial disease (13%), and adverse events (6%). Articular disease indices including Disease Activity Index for Psoriatic Arthritis (DAPSA), tender joints count (TJC) and Simplified Disease Activity Index (SDAI) were significantly lower at 6 and 12 months (DAPSA 1.5-2 levels reduction; p = 0.018 and 1-1.5 levels reduction; p = 0.031, respectively; TJC -2.16 [-4.0, -0.3]; p = 0.025 and -1.69 [-3.09, -0.28]; p = 0.022, respectively; SDAI -10.13 [-16.4, -3.8], p = 0.003 and -12.2 [-17.1, -7.2], p = 0.0002, respectively). PASI75 at 6 and 12 months was achieved by 63% and 57%, respectively, and PASI100 at 6 and 12 months by 31% and 21%, respectively. Conclusion: Patients with resistant PsA, including inadequate response to secukinumab, demonstrated a good response to ixekizumab, albeit limited on time. Within class switch from secukinumab to ixekizumab may be a plausible therapeutic option in PsA patients following secukinumab failure.
