A to Z of MS Neutralising antibodies

Antibodies are created by the immune system as part of the response to foreign objects, such as bacteria and viruses. Antibodies are proteins that lock onto the surface of an invading particle helping the body to kill it off.

It is known that some people with multiple sclerosis develop antibodies to the beta interferon drugs (Avonex, Betaferon, Extavia and Rebif) and natalizumab (Tysabri). These are known as neutralising antibodies as they may reduce the effectiveness of these drugs. Over the long-term, this may mean that people taking the beta interferons or natalizumab receive less benefit from the treatment and experience a similar number of relapses as they would have done before taking the drugs.

About 30% of people on interferon beta 1b (Betaferon or Extavia), 25% on Rebif, and 5% on Avonex will develop neutralising antibodies. In some people the neutralising antibodies will disappear again over time. Around 6% of people taking Tysabri develop persistent neutralising antibodies, which are usually evident from around three months of treatment.

A review by the European Forum of Neurological Sciences in 2005 recommended that people receiving the beta interferon drugs should be tested for neutralising antibodies at 12 months and two years after starting treatment. If neutralising antibodies continue to be present at two years, are present in high levels, and an individual is beginning to experience more MS-related symptoms, then there is a case for stopping or switching treatment. However, the presence of neutralising antibodies alone is not a reason to stop or to change drugs unless there is other evidence that the treatment is not working. The neurologist will make a decision which should be in partnership with the individual.

There are as yet no clinical guidelines about testing for neutralising antibodies with Tysabri, and this will depend on the neurologist's discretion.

Although neutralising antibodies can limit the effectiveness of treatment and a study of test tube samples did suggest that they could also affect naturally occurring beta interferon within the immune system, neutralising antibodies are not associated with any new side effects or long-term safety issues.

Antibodies have been shown to develop in some people who take glatiramer acetate (Copaxone), although one study suggests that this had no influence on the effectiveness of the drug.

Anyone who develops neutralising antibodies may be eligible to switch to another treatment, eg to glatiramer acetate from beta interferon. However, this will depend on individual experience and the neurologist's discretion.

References

Calabresi PA, et al.
The incidence and significance of anti-natalizumab antibodies: results from AFFIRM and SENTINEL.
Neurology 2007;69(14):1391-1403.
abstract

Sorensen PS, et al.
Guidelines on use of anti-IFN-beta antibody measurements in multiple sclerosis: report of an EFNS taskforce on IFN-beta antibodies in multiple sclerosis.
European Journal of Neurology 2005;12(11):817-827.
abstract

Sominanda A, et al.
Inhibition of endogenous interferon beta by neutralizing antibodies against recombinant interferon beta.
Archives of Neurology 2010;67(9):1095-1101.
abstract

Teitelbaum D, et al.
Antibodies to glatiramer acetate do not interfere with its biological functions and therapeutic efficacy.
Multiple Sclerosis 2003;9(6):592-599.
abstract

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