Amgen (AMGN) and AstraZeneca (AZN) announced that results from a Phase 2 study evaluating brodalumab in 168 patients with psoriatic arthritis were published in The New England Journal of Medicine. These data will also be presented at the 2014 European League Against Rheumatism Annual Congress in Paris on June 14.. Brodalumab is the only investigational treatment in development that binds to the interleukin-17 receptor and inhibits inflammatory signaling by blocking the binding of several IL-17 ligands to the receptor. The IL-17 pathway plays a central role in inducing and promoting inflammatory disease processes. The study showed that treatment with brodalumab significantly improved signs and clinical symptoms associated with the disease, including tender and swollen joints, at 12 weeks as measured by a 20% improvement in the American College of Rheumatology response criteria. The study also showed that many patients continued to improve, and that the improvements were sustained, through the first 52 weeks of the study reported in NEJM. The study achieved its primary endpoint with both doses of brodalumab exhibiting superiority to placebo in ACR20 responses at week 12. These responses continued to improve through 24 weeks and were sustained through the first 52 weeks of the study.1 ACR response criteria are a measure of improvement in tender and swollen joints, as well as patient and physician global assessments of disease activity, pain, disability and inflammatory markers. A 20% improvement from baseline in ACR response rates is known as ACR20, a 50% improvement from baseline is known as ACR50 and a 70% improvement from baseline is known as ACR70.