In an extension period of the phase 3 SPIRIT-P1 study (ClinicalTrials.gov identifier: NCT01695239), treatment with ixekizumab demonstrated sustained efficacy and a favorable safety profile in patients with active psoriatic arthritis (PsA) previously naïve to biologic disease-modifying antirheumatic drugs (bDMARDs). Results of this extension phase study were published in The Journal of Rheumatology.

Patients who participated in the study were randomly assigned to one of three treatment arms at baseline: (1) ixekizumab 80 mg every 2 or 4 weeks following a 160-mg starting dose (2) adalimumab 40 mg every 2 weeks, or (3) placebo. At week 24 (week 16 for inadequate responders), patients in the adalimumab and placebo groups were re-assigned to receive ixekizumab either every 2 or every 4 weeks.

 A total of 381 participants entered the extension phase of the study. In the treatment groups that received ixekizumab every 2 or 4 weeks from baseline, American College of Rheumatology (ACR) response rates of 20% (68.8% and 69.1%, respectively), 50% (53.1% and 54.6%, respectively), and 70% (39.6% and 39.2%, respectively) were sustained at week 52. Patients who were re-assigned to receive ixekizumab also demonstrated efficacy measured by ACR response rates at week 52.


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A similar response pattern was reported for Psoriasis Area and Severity Index outcomes. In all treatment groups, radiographic progression was minimal. The adverse events most often reported (≥4%) included nasopharyngitis, injection-site reaction, injection-site erythema, upper respiratory tract infection, and back pain. No deaths were reported in the study. 

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The investigators concluded that in the extension phase of this study, treatment with ixekizumab every 2 or 4 weeks was associated with sustained efficacy in key PsA domains, with a safety profile consistent with that of other studies evaluating ixekizumab therapy. These findings support treatment with ixekizumab in patients with PsA who are naïve to bMARDs.

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Reference

van der Heijde D, Gladman DD, Kishimoto M, et al. Efficacy and safety of ixekizumab in patients with active psoriatic arthritis: 52-week results from a phase III study (SPIRIT-P1) [published online December 15, 2017]. J Rheumatol. doi:10.3899/jrheum.170429