The U.S. Food and Drug Administration has approved Kineret(TM) (anakinra) for the reduction of signs and symptoms of moderately to severely active rheumatoid arthritis (RA) in adult patients who have failed one or more disease modifying antirheumatic drugs (DMARDs).
Kineret, produced by Amgen, is the first direct and selective blocker of interleukin-1 (IL-1), a protein present in excess in RA patients. By blocking IL-1, Kineret inhibits the inflammatory response in RA including pain, and can be used alone or in combination with DMARDs, other than Tumor Necrosis Factor (TNF) blocking agents.
Approval of Kineret was based on a total of 2,932 patients studied in randomized, double-blinded, placebo-controlled clinical trials. Of the total patients, more than 2,600 were treated with Kineret. Kineret, taken alone or in combination with other commonly used disease-modifying therapies, improves the signs and symptoms of RA. Many clinical responses, including a decrease in inflammation and pain, were seen by the fourth week of treatment and most were seen by week 13.
After six months of therapy, 38 percent of Kineret patients, as compared with 22 percent of placebo patients, achieved a 20 percent improvement in the American College of Rheumatology (ACR) criteria. ACR20 criteria include a 20 percent improvement in the number of swollen and tender joints, plus a greater than or equal to 20 percent improvement in at least three of five of the following criteria: physician assessment of disease, patient assessment of disease, pain, C-reactive protein (a general laboratory marker of inflammation) and health assessment questionnaire.
“Kineret worked for many of my patients,” said Dr. Stanley Cohen, clinical associate professor, University of Texas Southwestern Medical Center, and a clinical investigator in the Kineret trials. “I am impressed with the improvements in my patients’ painful and swollen joints.”
The most common side effect was a usually mild reaction at the site of injection, characterized by redness, swelling and pain. There was a risk of serious infections (2 percent in Kineret patients vs. less than 1 percent in placebo patients) in the clinical trials. Although Kineret should be discontinued if a patient develops an infection, most patients can continue taking Kineret after their infection resolves. Kineret should not be used with TNF blocking agents etanercept and infliximab. Preliminary data suggest a higher incidence of serious infection (7 percent) and the occurrence of neutropenia (3 percent) when Kineret is used with these agents.