Efficacy of ixekizumab in different phenotypes of patients with active psoriatic arthritis: results from the SPIRIT trials

Background/purpose: Ixekizumab (IXE) is approved for the treatment of moderate‐to‐ severe psoriasis and more recently for active psoriatic arthritis (PsA). Objective: To describe the efficacy of IXE at week 24 in PsA patients with different disease manifestations and characteristics. Methods: Biologic naïve patients (SPIRIT‐P1) were randomized to 80‐mg IXE (initial dose 160 mg) every 4 (Q4W; N = 107) or 2 weeks (Q2W; N = 103), to adalimumab 40‐mg IXE (Q2W; N = 101), or placebo (PBO; N = 106). Patients with an inadequate response or intolerance to TNF inhibitors (SPIRIT‐P2) were randomized to IXE Q4W (N = 122) or Q2W (N = 123), or PBO (N = 118). Patients had active disease with ≥3TJC and ≥3SJC and were classified according to the following phenotypes of PsA: polyarthritis (≥5TJC and/or ≥5SJC), oligoarthritis (<5TJC and <5SJC), DIP joint only, enthesitis and dactylitis. in each phenotype ACR 20, 50 and 70 response criteria, Minimal Disease Activity Psoriasis Area Severity Index (MDAPASI), and Disease Activity Psoriatic Arthritis (DAPSA) remission and low disease activity (LDA) response criteria were assessed to evaluate IXE effect at week 24 combining both doses. For each phenotype with a sufficient sample size, IXE‐and PBO‐treated patients' baseline characteristics were assessed. Treatment effects of IXE and PBO were compared using Chi‐square tests (or Fisher's exact tests) within each phenotype. Results: The largest phenotypes were polyarthritis (N = 662), enthesitis (investigator: N = 459; LEI > 0: N = 403), and dactylitis (investigator: N = 220; LDI‐B > 0: N = 155). Too small sample sizes due to inclusion criteria or low frequency were observed for “DIP joint only”, oligoarthritis and arthritis mutilans phenotypes (N = 22, N = 17 and N = 15). Baseline patient characteristics were generally balanced between treatment arms and similar between the 3 largest phenotypes, with no difference in disease activity and duration. Response rates were consistent to overall efficacy reported with IXE in SPIRIT trials. Conclusion: Treatment responses with IXE at week 24 were consistent across all phenotypes evaluated. (Table Presented).