The results from the 2-year AIM (ABA in Inadequate responders to MTX) trial indicated that RA patients refractory to treatment with MTX, demonstrate significant reduction in radiographic progression after treatment with Abatacept (Aba) [Ann Rheum Dis 2005;64(Suppl III):56].

In a 2 year follow-up study, Aba (∼10 mg/kg) slowed progression of structural damage when compared with placebo, as determined from radiographs of hands and feet. Paired radiographs were independently scored for erosion score (ES), joint-space narrowing (JSN) score, and total score (TS) using the Genant-modified Sharp scoring method [Am J Med 1983;75(6A):35–47].

After 2 years of treatment with Aba, signs of radiographic progression were minimal. Using a linear mixed model analysis to compare the slope of radiographic progression, 2 years of treatment with Aba was found to be significantly better than 1 year of placebo followed by 1 year of Aba (ES p<0.001; JSN p<0.05; TS p<0.01). Radiographic progression in the Aba group slowed more after 2 years of treatment than after 1 year. The slopes from year 1 to year 2 were: ES-0.6 vs 0.3; JSN- 0.4 vs 0.4; TS- 1.0 vs 0.7. Results of this study indicate that after 2 years of treatment, Aba significantly slowed radiographic progression in RA patients with an inadequate response to MTX. The effect seen after 2 years of treatment was significantly better than that seen after 1 year.