Among patients with psoriatic arthritis (PsA), ixekizumab may be superior to adalimumab in terms of joint and skin improvement, according to study results published in Annals of the Rheumatic Diseases.

Results of the SPIRIT head-to-head trial indicated that ixekizumab was superior to adalimumab with regard to the achievement of the American College of Rheumatology (ACR)50 and Psoriasis Area and Severity Index (PASI)100 responses at 24 weeks..

The 52-week, multicenter, phase 3b/4, open-label, randomized, blinded-assessor study (ClinicalTrials.gov Identifier: NCT03151551) aimed to investigate the efficacy and safety of ixekizumab compared with adalimumab in adults with PsA. Patients with inadequate response to conventional synthetic disease-modifying antirheumatic drugs (DMARDs) and no previous exposure to biologic DMARDs were randomly assigned 1:1 to receive either ixekizumab or adalimumab. The primary outcome was superiority of ixekizumab to adalimumab according to ACR50 and PASI100 responses after 24 weeks. Prespecified outcomes after 52 weeks included musculoskeletal, psoriasis, quality of life outcomes, and safety.

The study cohort included 566 patients, of whom 283 received ixekizumab and 283 received adalimumab. Of the total cohort, 246 participants (87%) who received ixekizumab and 237 (84%) who received adalimumab completed the 52-week study visit.


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At week 52, treatment with ixekizumab vs adalimumab was associated with a higher percentage of patients achieving both ACR50 and PASI100 (39.2% vs 26.1%, respectively; P <.001). Differences between the groups were evident after 8 weeks, and maintained throughout the study. A significantly higher percentage of patients who received ixekizumab achieved PASI100 (64.3% vs 41.3%, respectively; P ≤.001). However, similar response rates for ACR50, ACR20, and ACR70 were observed with ixekizumab and adalimumab, as were other efficacy outcomes, including treat-to-target outcomes, enthesitis, and dactylitis resolution.

When used as monotherapy for 52 weeks, ixekizumab was superior to adalimumab for simultaneous achievement of ACR50 and PASI100 (38% vs 19%, respectively; P =.007), and PASI100 responses (66% vs 35%, respectively; P <.001). While response rates were higher with a combination of adalimumab and conventional synthetic DMARDs vs adalimumab monotherapy, response rates for ixekizumab were consistent irrespective of concomitant conventional synthetic DMARD use.

There were no new safety findings for either ixekizumab or adalimumab.

The study had several limitations, including the open-label design, potential assessment bias, and no available data on antidrug antibodies to ixekizumab or adalimumab.

“SPIRIT-H2H study comparing ixekizumab [vs] adalimumab is the first fully disclosed direct head-to-head study in PsA; its findings over 52 weeks will inform future treatment recommendations and may impact selection of therapy in bionaive patients with active PsA,” the researchers concluded.

Disclosure: This clinical trial was supported by Eli Lilly and Company. Please see the original reference for a full list of authors’ disclosures.

Reference

Smolen JS, Mease P, Tahir H, et al. Multicentre, randomised, open-label, parallel-group study evaluating the efficacy and safety of ixekizumab versus adalimumab in patients with psoriatic arthritis naïve to biological disease-modifying antirheumatic drug: final results by week 52. Published online July 13, 2020. Ann Rheum Dis. doi:10.1136/annrheumdis-2020-217372