OP0104 EFFICACY OF ABATACEPT (CTLA4Ig; BMS-188667) IN COMBINATION WITH METHOTREXATE IN THE TREATMENT OF EARLY AND ESTABLISHED RHEUMATOID ARTHRITIS
E. Keystone, J. Sibilia, S. Steinfeld, I. Nuamah, R. Aranda, J. Becker

Abatacept, also known as CTLA4g, blocks a co-stimulatory signal required for T cell activation. Earlier studies (see Eular 2002 highlights) have shown that CTLA4Ig appears to be well tolerated and efficacious in patients with active RA receiving methotrexate (MTX). Here, Keystone et al compare ACR responses of patients receiving combination therapy of abatacept plus MTX to patients receiving MTX alone. Response rates are also compared based on disease duration.

Methods: Patients with active rheumatoid arthritis (RA) despite MTX with similar demographics were randomized to one of two treatment groups, abatacept 10m/kg + MTX (n=115) or MTX alone (n=119). ACR20, 50, and 70 are measured following 12 months of therapy.

Results: A statistically significantly greater proportion of patients in the abatacept + MTX group achieved ACR 20, 50 and 70 responses at 12 months compared with MTX alone (ACR 20: 63 vs 36%, p<0.001; ACR 50: 42 vs 20%, p<0.001; ACR 70: 21 vs 8%, p<0.05). Additionally, a greater percentage of patients in the abatacept + MTX group with disease duration < 3 years (n=41) achieved ACR20, 50, and 70 compared to patients with disease duration > 3 years (n=74), although this difference did not reach statistical significance.

Conclusion: In patients with RA, combination therapy with abatacept + MTX is significantly more efficacious than therapy with MTX alone. There was a trend suggesting greater improvement in ACR response rates in patients with shorter disease duration.

Editorial Comments: As with all other biologics tested to date, abatacept in combination with MTX is more effective than MTX alone. The critical missing piece of information is what happens to radiographic progression in the 2 groups.

Also, although the ACR responses in the "early" RA group were higher than those with longer duration RA, so were the corresponding placebo responses. If one subtracts the placebo responses from the treatment responses, the differencs in the early versus late RA groups are nearly identical as shown below.

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