Background 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 (PBO) in improving the signs and symptoms of psoriatic arthritis (PsA) at Week 24 in biologic-naïve patients (pts).

Objectives To determine the efficacy and safety of IXE treatment up to 3 years in biologic-naïve pts with PsA.

Methods In SPIRIT-P1 (NCT01695239), 381 pts entered the extension period (EP; Weeks 24–156). Pts 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) pts initially randomised to IXE at Week 0. Modified non-responder imputation (mNRI; missing data treated as non-response for pts 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 pts who entered the EP; baseline was the first IXE dose during the EP.

Results Of the 210 pts initially randomised to IXE at Week 0 (ITT), 125 (60%) pts completed 156 weeks of treatment; 27 pts discontinued due to AEs, and 26 pts met the mandatory discontinuation criteria. Efficacy results are summarised (table 1). Improvements in ACR (American College of Rheumatology) and PASI (Psoriasis Area and Severity Index) responses, resolution in enthesitis and dactylitis, and improvements from baseline HAQ-DI (Health Assessment Questionnaire Disability Index), enthesitis, and dactylitis persisted up to Week 156. Safety assessments for all pts who entered the EP are summarised (table 2). Frequencies of treatment-emergent AEs (TEAEs) were similar between IXE Q4W and Q2W. The majority of TEAEs were mild or moderate in severity; serious AEs occurred in 47 pts.

Conclusions In pts 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.

Disclosure of Interest V. Chandran Grant/research support from: Abbvie, Consultant for: Abbvie, Amgen, Celgene, Eli Lilly and Company, Janssen, Novartis, Pfizer, UCB, R. Fleischmann Consultant for: AbbVie, Acea, Amgen, Bristol-Myers Squibb, Eli Lilly and Company, Novartis, Pfizer, Sanofi-Aventis, and UCB, E. Lespessailles Grant/research support from: Novartis, Eli Lilly and Company, Servier, and Amgen, Speakers bureau: Novartis, Eli Lilly and Company, P. Helliwell Grant/research support from: AbbVie, Amgen, Bristol-Myers Squibb, Celgene, Eli Lilly and Company, Janssen, Merck, Novartis, and UCB, O. Benichou Shareholder of: Eli Lilly and Company, Employee of: Eli Lilly and Company, J. Erickson Shareholder of: Eli Lilly and Company, Employee of: Eli Lilly and Company, C. Shuler Shareholder of: Eli Lilly and Company, Employee of: Eli Lilly and Company