THU0333 Efficacy and safety of ixekizumab in patients with active psoriatic arthritis: three year results from a phase 3 study (SPIRIT-P1)

Abstract

Objectives: Ixekizumab (IXE) is a high‐affinity monoclonal antibody that selectively targets interleukin‐17A. IXE, every 4 (Q4W) or 2 (Q2W) weeks, was superior to placebo in improving the signs and symptoms of psoriatic arthritis (PsA) at Week 24 in biologic‐naive patients. The objective of this study was to determine the efficacy and safety of IXE treatment up to 3 years in biologic‐naive patients with PsA. Methods: In SPIRIT‐P1, 381 patients entered the extension period (EP; Weeks 24‐156). Patients failing to demonstrate ≥ 20% improvement in both tender and swollen joint counts at Week 32, or any subsequent visit, were discontinued (mandatory discontinuation criteria). Ad‐hoc efficacy data are presented for intent‐to‐treat (ITT) patients initially randomized to IXE at Week 0. Modified non‐responder imputation (mNRI; missing data treated as non‐response for patients discontinued due to lack of efficacy or adverse events [AEs]; multiple imputation [MI] for all other missing data) was applied to categorical measures. Modified baseline observation carried forward (mBOCF) was applied to continuous efficacy measures. Safety assessments are presented for all patients who entered the EP; baseline was the first IXE dose during the EP. Results: Of the 210 patients initially randomized to IXE at Week 0 (ITT), 125 (60%) patients completed 156 weeks of treatment; 28 patients discontinued due to AEs, and 26 patients met the mandatory discontinuation criteria. Improvements in American College of Rheumatology (ACR) 20/50/70 (69%, 51% and 33% for IXE Q4W; 62%, 56% and 44% for IXE Q2W, respectively) and Psoriasis Area and Severity Index (PASI) 75/90/100 responses (63%, 51% and 44% for IXE Q4W; 69%, 65% and 61% for IXE Q2W, respectively), resolution in enthesitis and dactylitis (47% and 62% for IXE Q4W; 40% and 69% for IXE Q2W, respectively), and improvements from baseline Health Assessment Questionnaire Disability Index (HAQ‐DI: ‐0.4 for IXE Q4W and ‐0.5 for IXE Q2W) persisted up to Week 156. Frequencies of treatment‐emergent AEs (TEAEs) were similar between IXE Q4W and Q2W (76%). The majority of TEAEs were mild or moderate in severity; serious AEs occurred in 47 patients (15% for IXE Q4W and 10% for IXE Q2W). Conclusion: In patients treated with IXE, improvements in the signs and symptoms of PsA persisted up to 3 years. No unexpected safety signals were observed, and the safety profile was consistent with previous studies of IXE.