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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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