Efficacy and safety of ixekizumab in patients with active psoriatic arthritis with and without concomitant conventional disease-modifying antirheumatic drugs: SPIRIT-P1 and SPIRIT-P2 3-year results

INTRODUCTION/OBJECTIVES: To evaluate the three-year efficacy and safety of ixekizumab with and without concomitant conventional synthetic disease-modifying antirheumatic drug (csDMARD) use in patients with active psoriatic arthritis (PsA). METHOD: Patients with PsA who were biologic-naïve (SPIRIT-P1, NCT01695239) or had prior inadequate response to tumor necrosis factor inhibitors (SPIRIT-P2, NCT02349295) were randomized to receive 80-mg ixekizumab every four weeks after receiving 160-mg ixekizumab at baseline. Efficacy, safety, and immunogenicity were evaluated in this post-hoc analysis in three subgroups: (1) ixekizumab monotherapy, (2) ixekizumab and methotrexate (MTX), (3) ixekizumab and any csDMARD (including MTX). Missing data were imputed using multiple imputation for continuous variables and modified non-responder imputation for categorical variables. RESULTS: Efficacy was similar across the three subgroups with 59.1%, 67.0%, and 66.1% of ixekizumab-treated patients achieving 20% improvement in the American College of Rheumatology scale score at week 156. Radiographic progression of structural joint damage (SPIRIT-P1 only) was similarly inhibited across the three subgroups with several outliers. No new safety signals were reported, and 91.0%, 84.1%, and 83.2% in the three subgroups reported ≥ 1 treatment-emergent adverse event. At week 156, 15.9%, 13.1%, and 11.0% in the three subgroups had antidrug antibodies; most had low titer status. CONCLUSIONS: Ixekizumab showed sustained efficacy in treating patients with PsA for up to three years in monotherapy or in combination with MTX or any csDMARD. The three subgroups had similar safety and immunogenicity profiles, which supports that the use of concomitant MTX or csDMARDs does not seem to impact the benefit/risk profile of ixekizumab. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10067-022-06218-8.