Amgen Inc., of Thousand Oaks, Calif., and Astrazeneca plc, of London, reported phase II results in The New England Journal of Medicine, with data from the 168-patient study showing that brodalumab, a drug that targets the interleukin-17 receptor, significantly improved signs and clinical symptoms associated with psoriatic arthritis, including tender and swollen joints, at 12 weeks, as measured by a 20 percent improvement in the American College of Rheumatology (ACR20) response criteria.