VIENNA — Ixekizumab (Taltz), an interleukin-17A inhibitor that’s already approved for the treatment of psoriatic arthritis and axial spondyloarthritis in adults appears likely to be granted the same corresponding indications for children, based on initial results from an open-label, phase 3 trial that employed adalimumab as a reference.
With a safety profile comparable with that seen in adult patients, ixekizumab “met the prespecified criterion for success at 16 weeks,” reported Athimalaipet V. Ramanan, MD, PhD, of Bristol Royal Hospital for Children and Translational Health Sciences, Bristol, England.
In this multicenter, randomized, open-label trial called COSPIRIT-JIA, which is still ongoing, investigators enrolled 101 children with active juvenile PsA (JPsA) or enthesitis-related arthritis (ERA), which is akin to spondyloarthritis in adults.
The efficacy and safety data at 16 weeks were presented as a late-breaking abstract at the annual European Congress of Rheumatology. Dr. Ramanan said that the open-label extension to 104 weeks is underway and further follow-up out to 264 weeks is planned.
Nearly 90% Achieve ACR30
The trial had an adaptive design in which the first 40 patients without biologics experience were randomized to ixekizumab or adalimumab, stratified by JPsA or ERA diagnosis, and the following 61 patients with either no biologic experience or an inadequate response or intolerance to biologics all received ixekizumab. The drugs were dosed according to weight. Dr. Ramanan explained that a placebo-controlled trial was considered unethical because of the strong evidence of benefit from biologics for JPsA and ERA.
The trial easily met its predefined threshold for success, which required ≥ 80% probability, based on Bayesian analysis, that ≥ 50% of patients would have 30% improvement in American College of Rheumatology response criteria (ACR30) at week 16. ACR30 was achieved in 88.9% of those treated with ixekizumab overall vs 95.0% of those treated with adalimumab, but the trial was not designed as a head-to-head comparison. Rather, adalimumab served as a reference.
When compared for the distinct diseases, the ACR30 rates were also numerically lower for ixekizumab relative to adalimumab for both ERA (88.9% vs 93.8%) and JPsA (88.9% vs 100%), but all of the adalimumab patients were naive to biologics. In comparison, about 75% of patients receiving ixekizumab were biologic-therapy naive.
Response rates to ixekizumab overall were numerically higher for patients without previous biologic experience than for those with experience (90.0% vs 85.7%), and this was also the case for patients with ERA (92.5% vs 78.6%). However, in the JPsA group, biologic-experienced patients had higher numerical response rates to ixekizumab (100% vs 85.0%).
An ACR30 is not a clinical goal that satisfies most patients and clinicians, Dr. Ramanan conceded, but he noted that ACR50 was reached with ixekizumab by 81.5% with ERA and 74.1% with JPsA, and ACR70 was reached by 68.5% and 55.6%, respectively. The highest responses of ACR90 (27.8% and 33.3%) and ACR100 (14.8% and 25.9%) were lower but still substantial in the ERA and JPsA groups, respectively.
Through week 16, 58.0% of those treated with ixekizumab had an adverse event considered treatment-related. Nearly half were of mild severity, and the remainder were moderate. Only 3.7% were considered serious. No patient discontinued study treatment because of an adverse event.
In this study, the presence of at least three active peripheral joints was an inclusion criterion. The median age was about 13 years in the biologic-naive adalimumab and ixekizumab groups and 14 years in the ixekizumab biologic-experienced group. The youngest patient in the study was aged 5 years, and the oldest was aged 18 years. Although about 40% of patients were women in the two biologic-naive subgroups, it was 60% in the biologic-experienced group.
On average, patients in the biologic-naive group were entered about 1 year after diagnosis. In the experienced patients, the average duration of disease at entry was nearly 4 years. About 45% of patients remained on conventional synthetic disease-modifying antirheumatic drugs while receiving ixekizumab. The proportion was 35% in the adalimumab reference arm.