Interleukin-17 Edges TNF Inhibitor in Psoriatic Arthritis

Maureen Salamon

June 20, 2019

MADRID — In patients with psoriatic arthritis, the combined end point of skin clearance and reduced disease activity was better with ixekizumab (Taltz, Eli Lilly), an interleukin (IL)-17 inhibitor, than with adalimumab (Humira, AbbVie), a TNF inhibitor, early results from the SPIRIT-H2H (NCT03151551) trial show.

Some rheumatologists — especially those new to IL-17 inhibitors — believe it will give great skin responses, "but they're still banking on a TNF for the best musculoskeletal responses," said Philip Mease, MD, from the Swedish Medical Center and the University of Washington in Seattle.

"These data help shore up the platform for more confident use of IL-17s across the board," he told Medscape Medical News.

"In the United States, most rheumatologists are forced to use adalimumab as a first-line biologic by insurance companies," he explained. "But if the patient had an inadequate response to their first TNF agent and the physician is trying to decide on a second TNF" or another biologic, "this gives them a little more confidence that they're not doing the patient a disservice by moving to an IL-17."

Mease presented 24-week primary analysis results from the 52-week multicenter, randomized, open-label, assessor-blinded SPIRIT-H2H study during at a late-breaking clinical trials session here at the European League Against Rheumatism (EULAR) 2019 Congress.


Of the 566 study participants with active psoriatic arthritis who were naïve to biologic disease-modifying antirheumatic drugs, 283 were randomized to ixekizumab and 283 to adalimumab. In the ixekizumab group, 49 patients met the criteria for moderate to severe plaque psoriasis, as did 52 patients in the adalimumab group.

The primary end point at 24 weeks — a reduction in disease activity of at least 50% (ACR50) plus an improvement of 100% in Psoriasis Area and Severity Index score (PASI 100), indicating complete skin clearance — was achieved by significantly more patients in the ixekizumab group than in the adalimumab group (36% vs 28%; P < .05).

Ixekizumab also met key secondary end points, including noninferiority to adalimumab for patients achieving ACR50 (51% vs 47%) and superiority over adalimumab for patients achieving PASI 100 (60% vs 47%; P = .001).

"In the near future, ixekizumab still looks like a second-line agent," Mease said, alluding to health-insurer preference in the United States. "But from a purely academic point of view, this allows us to put the two on an equal playing field."

There were "no unexpected results based on what we know" from previous trials about each medication's safety profile, he added. For both drugs, the most common adverse reactions were mild to moderate and included infections and injection-site reactions.

We're doing better with skin but we need to be stronger with ACR 50/70. We're not there yet.

Audience members pointed out that although ixekizumab clearly performed better in skin measures, joint outcomes were similar between the two drugs.

"It was a very unique primary end point, somehow more convincing on the skin" results, said Thomas Dörner, MD, from Charité–Universitätsmedizin Berlin, who is chair of the EULAR scientific program committee.

The trial "confirms our clinical experiences, but is a strong indication that we need better drugs for psoriatic arthritis to control joint progression," Dörner told Medscape Medical News.

"We're doing better with skin but we need to be stronger with ACR 50/70. We're not there yet," he added.

The study was funded by Eli Lilly. Mease has financial relationships with AbbVie, Amgen, Bristol-Myers Squibb, Celgene, Galapagos, Genentech, Gilead, Janssen, Leo, Eli Lilly, Merck, Novartis, Pfizer, Sun Pharmaceutical Industries, Inc., and UCB. Dörner has financial relationships with Eli Lilly, Janssen, Roche, and UCB Pharma.

European League Against Rheumatism (EULAR) Congress 2019: Abstract LB0005. Presented June 15, 2019.

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