At a glance: Data supporting the approval of ixekizumab for PsA
At the end of 2017, the indication for ixekizumab was expanded to include psoriatic arthritis (PsA). Previously approved for plaque psoriasis, the interleukin (IL)-17A inhibitor may now be given to adult patients with active PsA in the USA, while the EMA has approved its use in adult patients with PsA and an inadequate response or intolerance to one or more DMARDs. Ixekizumab can be used alone or in combination with methotrexate.
The approval of ixekizumab for the treatment of PsA was based on the results of two phase III randomized controlled trials, SPIRIT-P1 and SPIRIT-P2, which are summarized below.
Patient population: Patients with PsA who had not received prior biologic treatment
Treatment groups: Subcutaneous injections of ixekizumab 80 mg once every 2 weeks (n=103), ixekizumab 80 mg once every 4 weeks (n=107), adalimumab 40 mg once every 2 weeks (n=101), or placebo (n=106)
As reported in the Annals of the Rheumatic Diseases in 2016, a significantly higher proportion of patients treated with ixekizumab every 2 weeks or every 4 weeks compared with placebo achieved at least a 20% improvement in ACR criteria (ACR20) from baseline to week 24, with corresponding rates of 62.1% and 57.9% versus 30.2%. The ACR20 response rate for adalimumab-treated patients was 57.4%.
Patients treated with either dose of ixekizumab also experienced significantly greater mean improvements in Disease Activity Score at 28 joints based on C-reactive protein (DAS28-CRP) and significantly less radiographic progression than those given placebo.
In all, 65.7% of patients treated with ixekizumab every 2 weeks and 66.4% of patients given ixekizumab every 4 weeks experienced treatment-emergent adverse events (TEAEs), compared with 47.2% of participants in the placebo group. The most commonly reported TEAEs were injection site reaction, injection site erythema, and nasopharyngitis, and the majority of adverse events were mild or moderate in severity.
Patient population: Patients with active PsA and an inadequate response or intolerance to prior treatment with TNF inhibitors
Treatment groups: Subcutaneous injections of ixekizumab at a starting dose of 160 mg followed by 80 mg every 2 weeks (n=123) or every 4 weeks (n=122), or placebo (n=118)
The SPIRIT-P2 results were reported in The Lancet in May 2017. Peter Nash (University of Queensland, Brisbane, Australia) and fellow investigators found that a significantly higher proportion of patients treated with ixekizumab versus placebo achieved an ACR20 response at week 24, with rates of 48% for patients given ixekizumab every 2 weeks, 53% for those in the ixekizumab every 4 weeks group, and 20% for participants receiving placebo.
Improvements in Health Assessment Questionnaire-Disability Index scores at week 24 were also significantly greater among patients in both ixekizumab groups compared with those given placebo.
A total of 7% of patients receiving ixekizumab every 2 weeks, 3% of those given the drug every 4 weeks, and 3% of placebo-treated patients experienced serious adverse events. The most frequently reported adverse events were injection site reaction, upper respiratory tract infection, and nasopharyngitis. No new safety concerns were identified.
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