Researchers said the drug was also well-tolerated in patients.
Izokibep led to statistically significant improvements in patients with psoriatic arthritis.
In a 46-week, randomized, double-blind, placebo-controlled, global phase 2 trial,1 researchers sought to determine the long-term efficacy and safety of the drug in patients with psoriatic arthritis. ACELYRIN, Inc. announced the trial outcomes in a press release.1
“Izokibep is a small protein therapeutic designed to inhibit interleukin-17A (IL-17A) with high potency and the potential for robust tissue penetration due to its small molecular size, about one-tenth the size of a monoclonal antibody,” the press release1 said.
Study participants were assigned to 1 of 3 groups: 80 mg izokibep, 40 mg izokibep, or 40 mg izokibep placebo treatment dosed every 2 weeks. Throughout the trial, researchers evaluated participants using the Psoriasis Area and Severity Index (PASI), American College of Rheumatology (ACR) response, and the Leeds Enthesitis Index (LEI).
At week 16 of the trial, participants in the placebo treatment group were asked to increase their dosage to 80 mg.
By the end of study, researchers were looking for endpoints of ACR50, ACR70, and PASI100, as well as participants’ overall enthesitis resolution. Some physicians consider ACR70 to be the best indicator of disease activity control.1 PASI100 is indicative of 100% improvement in skin, and enthesitis resolution is indicative of no active entheseal sites.
ACR responses indicate a percentage reduction in tenderness and swelling in the joints. Additionally, they require improvement in at least 3 of the following 5 areas:
By week 46 of the trial, 79% of participants in the 80 mg izokibepmet ACR50. 50% met ACR70, 71% met PASI100, and 89% had enthesitis resolution.
In the 40 mg izokibep group, 50% of participants met ACR50. 33% met ACR70, 50% met PASI100, and 83% had enthesitis resolution.
Participants generally did not experience severe treatment-emergent adverse events or effects as a result. However, injection site irritation that did occur was mild to moderate in nature, and declined in frequency as the trial progressed.
1 participant experienced a serious adverse event, vulvar cancer, which researchers deemed potentially drug-related.
Full trial results are expected to be presented at a later scientific meeting.1
"Patients want both rapid and meaningful improvement of their symptoms, as well as lasting–and ideally improving–resolution of disease over time,” said Philip J. Mease, MD, investigator in the izokibep psoriatic arthritis program.1 Mease is also the director of rheumatology research at the Swedish Medical Center in Seattle, Washington, and a clinical professor at the University of Washington School of Medicine.
“Building on the 16-week data for izokibep reported at EULAR and ACR last year, the 46-week data now show not only continued but marked improvements over time in key areas of psoriatic arthritis including joint pain, skin psoriasis and enthesitis,” Mease said.