Long-term safety, efficacy and inhibition of radiographic progression with abatacept treatment in patients with rheumatoid arthritis and an inadequate response to methotrexate: 3-year results from the AIM trial

Objective To evaluate abatacept treatment over 3 years in patients with rheumatoid arthritis (RA) refractory to methotrexate (MTX). Methods Patients randomised to abatacept or placebo (+ MTX) during the 1-year double-blind period of the A batacept in I nadequate responders to Methotrexate (AIM) trial received open-label abatacept (+ MTX) in the long-term extension (LTE). Safety was assessed for patients who received = 1 dose of abatacept, regardless of randomisation group. Efficacy was assessed for patients randomised to abatacept who entered the LTE. Results 433 and 219 patients were randomised and treated with abatacept or placebo, respectively; 378 and 161 entered the LTE. At year 3, 440/539 patients were ongoing. No unexpected safety events were observed in the LTE. By year 3, incidence rates of adverse event and serious adverse events were 249.8/100 and 15.1/100 patient-years, respectively. Incidence rates were generally stable over time. At year 3, 84.8%, 63.4% and 37.5% of patients achieved American College of Rheumatology (ACR) criteria of 20, 50 and 70, respectively, compared with 82.3%, 54.3% and 32.4% of patients at year 1. Mean changes in Genant-modified Sharp scores were reduced progressively over 3 years, with significantly greater inhibition during year 3 compared with year 2 (p=0.022 for total score). Conclusion In MTX-inadequate responders with RA, abatacept provided consistent safety and sustained efficacy over 3 years. The data suggest an increasing inhibitory disease-modifying effect on radiographic progression.