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 Abatacept in Inadequate 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.