Psoriatic arthritis patients treated with brodalumab improved by approximately 20%, compared with those on placebo, achieving the primary endpoint in a phase II trial, investigators reported online June 11 in the New England Journal of Medicine.
Brodalumab is a human monoclonal antibody targeting the interleukin-17 receptor A (IL-17RA). At week 12 of the 40-week randomized trial, 37%-39% of brodalumab patients had improved by at least 20% based on the American College of Rheumatology response criteria (ACR 20), compared with only 18% of the placebo patients (P = .03 and .02, respectively), reported Dr. Philip J. Mease of the Swedish Medical Center and the University of Washington, both in Seattle, and his associates.
Rates of 50% improvement in response criteria, or ACR 50, also exceeded placebo in both treatment arms (14%, compared with 4% for placebo; P = .05).
The researchers randomized 168 adults with psoriatic arthritis, of whom 159 finished the double-blind phase and 134 completed 40 weeks of the open-label extension (N. Engl. J. Med. 2014;370:2295-306 [doi: 10.1056/NEJMoa1315231]). By week 24, ACR 20 response rates were 51% for the 140-mg group, 64% for the 280-mg group, and 44% in placebo patients who switched to open-label brodalumab, said the researchers. Patients improved similarly whether they were treatment naive or had received previous biologic therapy, the investigators added.
Adverse events were comparable between the treatment and placebo groups, with no opportunistic infections or deaths, the investigators reported. Two patients tested positive for antibodies to brodalumab. "No significant neutropenic events were reported – an important safety outcome, since interleukin-17 is involved in neutrophil homeostasis," the researchers said. They noted, however, that larger trials would be needed to detect rare adverse events.
Amgen, a maker of brodalumab, funded the study. Dr. Mease and his coauthors reported employment with or receiving grants from Amgen.
The study findings also were scheduled for presentation in a poster at EULAR 2014.