This summary of a Cochrane review presents what we know from research about the effect of abatacept on rheumatoid arthritis. Although expensive, if supported by the overall body of evidence, the claims of their benefit upon both symptoms and radiographic progression, and their low rate of short term side effects make them of great interest to patients with RA.
The review shows that in people with rheumatoid arthritis:
- Abatacept probably reduces joint damage as seen on the x-ray.
- Abatacept probably improves pain, function and other symptoms of rheumatoid arthritis.
- Abatacept probably reduces disease activity.
We do not have precise information about side effects and complications. This is particularly true for rare but serious side effects. Possible side effects may include a serious infection or upper respiratory infection. Rare complications may include certain types of cancer.
What is rheumatoid arthritis and what is abatacept?
When you have rheumatoid arthritis, your immune system, which normally fights infection, attacks the lining of your joints. This makes your joints swollen, stiff and painful. The small joints of your hands and feet are usually affected first. There is no cure for rheumatoid arthritis at present, so the treatments aim to relieve pain and stiffness and improve your ability to move.
Abatacept is one of a group of medications called selective costimulation modulators (immunomodulators). It works by blocking the activity of T-cells, a type of immune cell in the body that causes swelling and joint damage in people who have rheumatoid arthritis.
Best estimate of what happens to people with rheumatoid arthritis who take abatacept:
X-rays of the joints
-There was no damage to joints of people who took abatacept after 12 months.
-The damage to joints of people who took a placebo was 0.27 units on a scale of 0 to 145 units.
Pain (higher scores mean worse or more severe pain)
- People who took abatacept rated their pain to be 12 points lower on a scale of 0 to 100 after 12 months with abatacept (12% absolute improvement).
-People who took abatacept rated their pain to be 37 on a scale of 0 to 100 after 12 months.
-People who took a placebo rated their pain to be 49 on a scale of 0 to 100.
ACR 50 (number of tender or swollen joints and other outcomes such as pain and disability)
-20 more people out of 100 experienced improvement in the symptoms of their rheumatoid arthritis after 12 months with abatacept (20% absolute improvement).
-37 people out of 100 experienced improvement in the symptoms of their rheumatoid arthritis.
-17 people out of 100 who took a placebo experienced improvement.
Physical Function
-25 more people out of 100 had better physical function after 12 months with abatacept (25% absolute improvement).
-64 people out of 100 had better physical function.
-39 people out of 100 who took a placebo had better physical function.
Disease activity
-32 more people out of 100 were considered to have low disease activity of their rheumatoid arthritis after 12 months with abatacept (32% absolute improvement).
-42 people out of 100 were considered to have low disease activity of their rheumatoid arthritis.
-10 people out of 100 who took a placebo were considered to have low disease activity of their rheumatoid arthritis.
There is moderate-level evidence that abatacept is efficacious and safe in the treatment of rheumatoid arthritis. Abatacept should not be used in combination with other biologics to treat rheumatoid arthritis. The withdrawal and toxicity profile appears acceptable at the present time but further long-term studies and post-marketing surveillance are required to assess harms and sustained efficacy.
Abatacept inhibits the co-stimulation of T cells and disrupts the inflammatory chain of events that leads to joint inflammation, pain, and damage in rheumatoid arthritis.
To assess the efficacy and safety of abatacept in reducing disease activity, pain, and improving function in people with rheumatoid arthritis.
We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2007, Issue 1), MEDLINE (from 1966), EMBASE (from 1980), ACP Journal Club (from 2000), and Biosis Previews (from 1990) in March 2007 and December 2008. We contacted authors of included studies and the abatacept manufacturer.
Randomized controlled trials comparing abatacept alone, or in combination with disease-modifying anti-rheumatic drugs (DMARDs) or biologics, to placebo or other DMARDs or biologics in patients with moderate to severe rheumatoid arthritis.
Two authors independently assessed search results and risk of bias, and extracted data. We obtained adverse event data from trials, long-term extension studies, and regulatory agencies.
Seven trials with 2908 patients were included. Compared with placebo, patients in the abatacept group were 2.2 times more likely to achieve an ACR 50 response at one year (RR 2.21, 95% confidence interval (CI) 1.73 to 2.82) with a 21% (95% CI 16% to 27%) absolute risk difference between groups. The number needed to treat to achieve an ACR 50 response was 5 (95% CI 4 to 7). Significant improvements in physical function and a reduction in disease activity and pain were found in abatacept-treated patients compared to placebo. One RCT found abatacept significantly slowed the radiographic progression of joint damage at 12 months compared to placebo, although it is not clear what the clinical relevance of this difference may be. There may be a risk of attrition bias. Total adverse events were greater in the abatacept group (RR 1.05, 95% CI 1.01 to 1.08). Other harm outcomes were not significant with the exception of a greater number of serious infections at 12 months in the abatacept group (Peto odds ratio 1.91 (95% CI 1.07 to 3.42). Serious adverse events were increased when abatacept was given in combination with other biologics (RR 2.30, 95% CI 1.15 to 4.62).