Key clinical point: When assessed by more holistic criteria, an interleukin-17A inhibitor resolved more psoriatic arthritis symptoms than a tumor necrosis factor inhibitor.
Major finding: Ixekizumab produced the primary efficacy endpoint in 36% of patients, while adalimumab achieved it in 28%.
Study details: SPIRIT-H2H, a multicenter, international, randomized study with 566 enrolled patients with active psoriatic arthritis.
Disclosures: SPIRIT-H2H was sponsored by Eli Lilly, the company that markets ixekizumab (Taltz). Dr. Mease has been a consultant to, speaker for, and received research funding from Eli Lilly and from several other companies. Dr. Fleischmann has been a consultant to and has received research funding from several companies including Eli Lilly.
The results from SPIRIT-H2H confirm with rigorously-collected, prospective data what we had already seen during our routine use of ixekizumab for treating patients with psoriatic arthritis: it does a better job of resolving skin manifestations than any tumor necrosis factor (TNF) inhibitor. For joint symptoms, the two drugs are similar, but for skin ixekizumab has substantial superiority.
I had been hopeful that inhibition of interleukin-17 would surpass TNF inhibition for resolution of joint symptoms, but it looks like they are similar. That’s a little below expectations. But working well for improving skin symptoms is important because it’s something that many patients care about, especially those with more substantial skin symptoms. When matching the best drug to each PsA patient other considerations also exist, such as ease of use. These drugs are delivered by different devices, and ease of administration also matters to patients.
I think it would be premature to presume that the effects shown by ixekizumab extrapolate to all the other interleukin-17 inhibitors. Some of these drugs act via different mechanisms, and so the SPIRIT-H2H results may very well not reflect a class effect.
Thomas Dörner, MD, is professor of rheumatology at Charité University Hospital in Berlin. He has been a consultant to Eli Lilly, as well as to AbbVie, Celgene, Novartis, Pfizer, and Roche, he has been a speaker on behalf of Amgen, Biogen, and Celgene, and he has received research funding from Chugai, Janssen, Roche, and Sanofi. He made these comments in an interview.