Anti-TNF is a disease modifying drug. This means it acts on the specific chemicals involved in AS change. Drugs like aspirin and ibuprofen act on the symptoms of AS but do not change the actual disease itself. Treatments like sulfasalazine may be effective in people with arthritis in the hands and feet (ie non-spinal disease) but have only small effects on severe AS and arthritis mainly in the spine. However, high level of TNF are found in the sacroiliac joints of patients with ankylosing spondylitis. If the TNF itself could be removed, then we could prevent damage to these joints and so actually alter the disease progression. Potentially anti-TNF should reduce the fatigue, pain, swelling, improve mobility and prevent further damage. High TNF levels are also found in people with psoriatic arthritis, rheumatoid arthritis and crohn's disease, and these conditions also improve with anti-TNF.

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Is there evidence that anti-TNF does stop the inflammation involved in ankylosing spondylitis ?

There have been dramatic and impressive results in the 300 people with AS who have been involved the trials carried out (in Germany, Belgium, Canada, Spain, England, France and America). For example 18 patients in Canada showed excellent improvement in function, disease activity, fatigue, pain and radiological imaging (MRI). In the short term (over 14 weeks) it was a very effective treatment. In all trials to date there has been a dramatic reduction in symptoms of AS and in the progression of joint destruction. In ankylosing spondylitis both spinal symptoms and peripheral (i.e. hands, feet, knees etc) involvement show fast and significant improvement. Anti-TNF also works to give great improvement in the disorders associated with spondylitis such as psoriasis and crohns disease (though not ulcerative colitis). It has been used for up to 5 years in patients with Rheumatoid Arthritis and in these patients the improvement in symptoms was sustained and the anti-TNF was shown to protect the joints from further structural damage. Current work suggests that anti-TNF seems even more effective in AS than in rheumatoid arthritis. 

In the trials carried out to date the reduction in disease activity has been between 50%-93%. Positive effects can occur as early as one day after treatment and last for 12 weeks. The best responses have been obtained in people with early disease. However, even in people with almost complete fusion there was still 45% improvement in disease activity at after 30 weeks (ie 7 months) of treatment. 

In a small trial on 29 people, anti-TNF seems to have help reduce osteoporosis. After 6 months the people taking part in the trial showed a higher bone mineral density. 

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Does everyone who takes it get this dramatic reduction in disease ?

No. The effect does vary with different individuals. There are some non-responders in all trials (i.e. no change in disease). However, about 80% of people do show an improvement. This is still very impressive for a new drug.

Are there any problems with anti-TNF ?

Yes. There is some need for caution. :

Complete remission of disease has rarely been seen. So some inflammation does appear to remain and this means that other chemicals are also involved in the inflammatory process and these are not affected by anti-TNF.

When the anti-TNF therapy is stopped the ankylosing spondylitis comes back. Therefore a person needs to continue taking the anti-TNF, perhaps for life.

There is the possibility that the body could become immune/accustomed to the anti-TNF and after a time it may not work. Therefore, it is possible that anti-TNF may not work for life.

As with any drug which affects the immune system (i.e. reduces inflammation) there is the risk of infection as the body’s’ ability to defend itself is reduced. Upper respiratory infections are more common among people taking anti-TNF and there have been cases of tuberculosis reported. [1-5 in 10,000 people taking the drug]. Other infections reported include : pneumonia and meningitis. The increased risk of pneumonia is 0.5% or 1 in 200. Therefore, if a person carries the TB bacteria this may become active when taking anti-TNF. 

Some rheumatologists feel that because the immune system is suppressed , there may be a theoretical risk of developing some types of cancer. However, there has been no increased occurrence of cancer in people taking anti-TNF to date. 

Some people [1 in 1000] develop lupus like disease (this is another autoimmune arthritis) which goes away when the anti-TNF treatment is stopped.

People with congestive heart failure can not take anti-TNF.

The reasons that people have stopped taking part in trials also include : septic osteomyelitis (ie infection of the bone) and hypersensitivity (ie a skin reaction where the drug is injected). 20% of people taking infliximab (one type of anti-TNF) showed a local skin reaction and 3% (or 3 in 100) stopped the drug due to the skin reaction. 

Many of these side effects are rare and some of the risks are theoretical. However, because of these risks anti-TNF is currently only considered for people with severe and active ankylosing spondylitis.

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Can I get anti-TNF from my doctor ?

Anti-TNF became available in Europe in May 2003. However, it is very expensive and it is not as easy to take as pill. There are 2 types of anti-TNF. 

Infliximab which needs to be given as an intravenous infusion. This means attending a hospital and having the drug by drip, slowing releasing it into the blood stream over the period of 2 hours. This needs to be done every 6-8 weeks. 

Etanercept which is self injected much the same as people who are diabetic inject themselves. People give themselves an injection twice a week. 

Thus in summary, anti-TNF is very new and exciting and the first disease modifying drug to have a significant effect in ankylosing spondylitis. Potentially anti-TNF could help a great number of people in the future. However, it is too early to be sure of the long term benefits and side effects of this therapy.

References :

Braun J et al. Thera py of ankylosing spondylitis and other spondyloarthritides : established medical treatment , anti-TNF alpha therapy and other novel approaches. Arthritis Res. 2002; 4(5): 307-21.

Maksymowych WP. et al. Infliximab in ankylosing spondylitis : a prospective observational inception cohort analysis of efficacy and safety. J Rheuamtol 2002; 29(5): 959-65.

Braun J. et al. Anti-tumour necrosis factor alpha therapy for ankyloising spondylitis : international experience. Ann Rheum Dis. 2002; 61 Suppl 3: III51-III60.

Braun J et al. Treatment of active ankylosing spondylitis with infiximab : a randomised controlled multicentre trial. Lancet 2002; 359 (9313): 1187-93.

Gorman J et al. Treatment of ankylosing spondylitis by inhibition of tumor necrosis factor alpha. N Engl J Med 2002; 346(18): 1349-56.

Sieper J et al. New treatment options in ankylosing spondylitis : a role for anti-TNF alpha therapy. Ann Rheum Dis 2001; 60 Suppl 3: iii58-61.

Marzo-Ortega H et al. Efficacy of etanercept in the treatment of the entheseal pathology in resistant spondylarthritipathy : a clinical and magnetic resonance imaging study. Arthritis Rheum 2001; 44(9): 2112-7.

Braun J, Sieper J, Breban M, Collantes-Estevez, Davis J, Inman R, Marzo-Ortega H, Mielants H. Anti-tumor necrosis factor alpha therapy for ankyloisng spondylitis: international experineces. Ann Rheum Dis 2002; 61: S111.

Dernis E, Roux C, Breban M, Dougados M. Infliximab in spondylarthropathy- Influence on bone mineral density. Clin Exp Rheumatol 2002; 20 (Suppl. 28): S185-S186. 

Antoni C, Braun J. Side effects of anti-TNF therapy : Current knowledge. Clin Exp Rheumatol 2002; 20 (Suppl. 28): S152-S157.

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