Disease modifying drug therapy What are disease modifying drugs?
Disease modifying drugs are used with a view to changing the long-term course of MS. They work by dampening down the inflammatory processes that cause relapses. By reducing the frequency and severity of relapses, some of these drugs have been shown to delay the long-term progression of MS.
Disease modifying drugs are designed to reduce the damage incurred as a result of relapses. For this reason they are only used in relapsing remitting MS and secondary progressive MS if relapses still occur. Where relapses do not occur, as in primary progressive MS, the current disease modifying drugs have not proven effective.
Types of MS
The different subtypes of MS are characterised as follows:
Relapsing remitting
Secondary progressive
Primary progressive
Benign
Initially, about two thirds of people have relapsing remitting MS. They experience relapses on average once or twice per year, with good or complete remission in between. However, there is a tendency for symptoms to worsen very gradually over time.
Within this particular subtype of MS a further distinctive form of MS has emerged, rapidly evolving severe relapsing remitting MS (RES). It is characterised by a high level of disease activity demonstrated by two or more disabling relapses within one year and signs of high disease activity on MRI. Rapidly evolving severe relapsing remitting MS is also referred to as highly active relapsing remitting MS.
People who start off with relapsing remitting MS may go on to develop a progressive form of the condition. Studies suggest that half of all people who are diagnosed with relapsing remitting MS have developed secondary progressive MS after ten years. The severity and frequency of relapses usually decrease, but disability slowly increases. It is only appropriate to use disease modifying drugs in secondary progressive MS if relapses continue to occur.
About 10% of people experience symptoms right from the start that become progressively worse over a period of years without remission.
Benign MS is associated with very occasional relapses, with good recovery in between and minimal symptoms over many years; therefore it can only be diagnosed retrospectively.
Clinically isolated syndrome (CIS)
In addition to the main subtypes of MS, clinically isolated syndrome (CIS) is also recognised as a distinct presentation of MS. CIS is an individual's first neurological episode lasting at least 24 hours. It is caused by inflammation or damage to the covering of nerves in one or more sites in the central nervous system (brain and spinal cord). Strictly speaking, a clinically isolated syndrome is not a subtype of MS as not everyone who experiences one will go on to develop MS.
Licensed disease modifying drugs
In the UK, there are currently six licensed disease modifying drugs for the treatment of MS. For ease of discussion they can be divided into two groups: self-administered drugs and a hospital-administered drug.
Self-administered drugs
- interferon beta - there are two forms of interferon beta:
- interferon beta 1a (brand names Avonex and Rebif)
- interferon beta 1b (brand names Betaferon and Extavia)
- glatiramer acetate (brand name Copaxone)
Hospital-administered drug
- natalizumab (brand name Tysabri)
It is important to recognise that disease modifying drugs are not a cure for MS; they can neither halt the progress of, nor reverse the damage that has already occurred in MS.
Different people will have different priorities and different goals when it comes to managing their condition; meaning that any decision made regarding drug treatment is very individual. While you need to give due consideration to how these drugs fit with your priorities, goals and lifestyle choices, due consideration should also be given to the mounting evidence to suggest that the earlier in the course of MS treatment commences, the more effective the drugs are. It is also important for any person starting drug treatment to recognise that, while these drugs are a long-term commitment, they are not necessarily a life-long commitment. While these drugs may prove effective over a long period of time, they will not necessarily maintain the same level of effectiveness. Your health professional will regularly review your treatment and advise if and when switching or stopping treatment altogether needs to be considered.