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DMTs, Treatment strategy

How immunosuppressed am I?

Do you understand the difference between short-term intermittent and long-term continuous immunosuppression? Here we address another of the key questions to consider before deciding on a specific disease-modifying therapy (DMT).

Key points

  • Immunosuppressive disease-modifying therapies (DMTs) reduce the immune system’s effectiveness.
  • It is important to weigh up the benefits and risks of short-term versus continuous immunosuppression.
  • Non-selective DMTs suppress the adaptive and innate immune systems; selective DMTs do not affect the innate immune system and are thus associated with a low risk of bacterial infections.
  • The implications of immunosuppression need to be considered within the context of other health and lifestyle factors.

Which DMTs cause immunosuppression?

A useful way of thinking about DMTs is based on whether they are immunosuppressive. Broadly speaking, an immunosuppressive is any DMT that reduces the immune system’s activation or effectiveness. 

From a regulatory perspective, for a drug to be classified as immunosuppressive, it should: 

  • cause significant lymphopaenia or leukopenia (reduced white cell counts)
  • be associated with opportunistic infections (infections that don’t occur in people with a normal, healthy immune system)
  • reduce antibody and/or T-cell responses to vaccines 
  • increase the risk of secondary malignancies. 

Based on the above criteria, the interferon-beta preparations and glatiramer acetate are immunomodulatory rather than immunosuppressive. Teriflunomide is also an immunomodulatory therapy with the potential, albeit small, to cause immunosuppression. In real life, however, very few people with MS treated with teriflunomide develop significant lymphopaenia or leukopenia; if they do, we tend to stop the drug. The other licensed DMTs are immunosuppressive to a greater or lesser degree. 

Short-term versus continuous immunosuppression

The duration and intensity of immunosuppression further determine the risks. Short-term or intermittent immunosuppression associated with an immune reconstitution therapy (IRT) front-loads the risks, which decrease substantially once the immune system has reconstituted itself. In comparison, long-term continuous or persistent immunosuppression, which occurs with most maintenance DMTs, accumulates problems over time, particularly opportunistic infections and secondary malignancies.

Live vaccines are, in general, contraindicated in patients on continuous immunosuppressive therapies. However, someone with MS on an IRT who has reconstituted their immune system can tolerate and respond to live vaccines. The benefits of administering live vaccines always need to be balanced against the risks of the vaccine.

How immunosuppressed are you table updated format 180625 SS

The main characteristics of continuous persistent and short-term (intermittent) immunosuppression. Modified from Giovannoni, Curr Opin Neurol.1
AHSCT, autologous haematopoietic stem cell transplantation; PML, progressive multifocal leukoencephalopathy.

Selective versus non-selective immunosuppression

Immunosuppression that accompanies DMTs may be selective or non-selective. Non-selective therapies deplete and/or suppress both the adaptive immune system (T cells and B cells) and the innate immune system (monocytes, neutrophils and natural killer [NK] cells). Alemtuzumab, AHSCT (autologous haematopoietic stem cell transplantation) and mitoxantrone are non-selective and are therefore associated with acute bacterial infections such as listeriosis, nocardiosis and cytomegalovirus reactivation. In comparison, anti-CD20 agents (ocrelizumab and ofatumumab) and cladribine are selective, do not affect the innate immune system and are therefore associated with a low risk of acute bacterial infections. 

How immunosuppressed are you_MET vs IRT_2 Dec 2024

Classification of disease-modifying therapies for relapsing forms of MS. Modified from Giovannoni, Curr Opin Neurol.1
AHSCT, autologous haematopoietic stem cell transplantation.

Other considerations

Please note that the implications of immunosuppression are not black and white but interact with other factors such as:

These factors have been highlighted during the COVID-19 pandemic, particularly in relation to the risk of severe COVID-19 and the variations in vaccine responses among people with MS (including waning of the immune response).

It is important to realise that we can derisk (reduce the risk of) some complications associated with long-term immunosuppression and the use of DMTs. Please see the post entitled How can I reduce my chances of adverse events on specific DMTs?

References

  1. Giovannoni G. Disease-modifying treatments for early and advanced multiple sclerosis: a new treatment paradigm. Curr Opin Neurol 2018;31:233 ̶ 43.
Brain health and holistic management of MS, Causes and prevention of MS

What prognostic group do I fall into?

Having some idea of how bad your MS is, or not, will allow you to discuss important issues with your neurologist so that you can make an informed decision about your MS treatment.

Key points

  • It is hard to predict the disease course of MS accurately for an individual.
  • Population data allow us to define three broad prognostic MS categories: good, indeterminate or poor.
  • Given sufficient time, most people with MS will do badly without treatment.
  • Factors linked to poor prognosis in untreated people with MS are listed.
  • The wide use of disease-modifying therapies is changing the natural history of MS for the better.
  • Adopting a healthy lifestyle, in parallel with appropriate treatment, can help to improve outcomes.  

Predicting MS outcomes: an imperfect science

We can’t predict the prognosis of an individual person with MS very accurately. So don’t let your neurologist mislead you if he or she says you are likely to have benign MS. ‘Benign MS’ is a relative term and can only be used retrospectively once you have had MS for many years or decades. In the era before disease-modifying treatments (DMTs), most people with MS would eventually become disabled, which is why I prefer not to use the term benign MS to predict outcomes. I now use it as a treatment aim, because we want all people with MS to have benign disease.

Three broad prognostic categories

Applying population data to place an individual into a broad prognostic group is often helpful. It allows you to frame your disease in terms of potential outcomes and may help you balance the risks of some treatments against the potential impact of MS later in your life. Predicting outcomes in MS is comparable to an actuary working in the insurance industry; we try to give you an average prognosis with a wide range of possibilities or errors. For this reason, I try to keep it simple and classify people with MS into three prognostic categories: poor, indeterminate, or good. Poor in this context means that if you leave MS to its own devices and let it run its natural course, the average person in this category will do badly.

Most people with a predicted poor prognosis will do badly without treatment for their MS.

Given sufficient time, most people with MS will deteriorate without treatment. This is why I actively promote treatment based on the scientific rationale that preventing damage now will protect your brain reserve and cognitive reserve and improve your long-term outcome. This is the philosophy behind the MS Brain Health initiative and the report Brain health: time matters in multiple sclerosis,1 which everyone with MS should take time to read. 

Factors linked to poor prognosis

Below is a list of factors that have been linked to poor prognosis in people who have not received a DMT. If you have fewer than five of these factors, you are likely to have a good outcome. In comparison, people with ten or more of these factors fall into the poor prognostic group. Most people with MS fall into the intermediate (indeterminate) prognostic group, with 5–10 of these factors. Some of these baseline factors are modifiable,2,3 so you can make the effort to help improve your own prognosis. 

Please note that the factors listed here only apply to people with MS who are untreated.  It is clear that DMTs are changing the outcome of MS.

  1. Older age of onset (greater than 40 years).
  2. Male sex.
  3. Multifocal onset – more than one site in the nervous system involved with the initial attack.
  4. Efferent or effector system is affected early – that is, the motor (power), cerebellar (balance and coordination) or bladder and bowel functions.  
  5. Partial or no recovery from initial relapses – do you have residual deficits from your initial attacks?
  6. A high relapse rate in the first 2 years – that is, more than two relapses. 
  7. Early disability – an Expanded Disability Status Scale (EDSS) score > 3.0 within 5 years of symptom onset indicates a poor prognosis. You can calculate your EDSS using an online calculator (web-EDSS calculator).
  8. Abnormal magnetic resonance imaging (MRI) scan with large lesion load – more than nine T2 lesions (white blobs) on the baseline MRI.
  9. Active or enhancing lesions on your baseline (initial) MRI – enhancing lesions imply that the lesions are new and actively inflamed.
  10. Posterior fossa lesions on the MRI – these refer to lesions in the back of the brain that involve the brainstem and cerebellum.
  11. Lesions in the spinal cord on MRI.
  12. Obvious early brain atrophy on MRI – brain atrophy refers to premature shrinkage of the brain over and above what you would expect for your age. This information is unlikely to be available to you because neuroradiologists often do not measure or comment on it. 
  13. Retinal thinning on optic coherence tomography (OCT) – people with MS who have lost a lot of retinal nerve fibres do worse than people with a normal retina. Yes, the eye is truly a window into what is happening in the brain of someone with MS. 
  14. Abnormal cerebrospinal fluid – positive immunoglobulin (Ig) bands (known as oligoclonal bands, OCBs) in the spinal fluid.
  15. Raised neurofilament levels in your spinal fluid – this test may not be part of routine care at your neurology centre. Neurofilaments are proteins that are released from damaged nerve fibres, and high neurofilament levels indicate greater damage and poorer outcome than low levels.
  16. Low vitamin D levels – this is controversial, but several studies have shown that people with MS with low vitamin D levels do worse than those with higher levels. These observations do not necessarily imply that by taking vitamin D you will do better. Low vitamin D levels may be related to reverse causation, in that the MS-associated inflammation uses up vitamin D; more inflammation indicates worse MS and is therefore linked with greater depletion of vitamin D levels.
  17. Smoking – smokers with MS do worse than non-smokers. This is modifiable and it is one of many reasons why you should try and give up smoking. 
  18. Comorbidities – people with MS who are obese, have diabetes, prediabetes, hypertension or raised cholesterol do worse than people with MS without these comorbidities.4
  19. Cognitive impairment – people with MS with poor cognitive function do worse than people with MS with good cognition. You can’t really assess your own cognition at present; you need to have it tested by a neuropsychologist.

‘It won’t happen to me’

Humans have interesting psychology in that they tend to consider themselves to be the exception to the rule. Gamblers don’t enter a casino to lose; they always believe they will win. A person with lung cancer who starts chemotherapy believes they will be one of the 10% who is cured. When someone is diagnosed with MS, they believe they will be one of the 30% with benign disease. (The current view among MS neurologists is that 30% of untreated people with MS will have benign disease.) 

This definition of ‘benign MS’ is based on having no or little disability at 15 years since onset, i.e., an EDSS score of 3.0 or less (no visible disability). However, when you interrogate people with so-called benign MS you find that more than 50% of them have hidden symptoms of depression, anxiety or cognitive impairment. Can we really justify this definition of benign MS? What is more, when you follow people with benign MS past 15 years, only 15% remain benign at 25 years and 5% at 30 years. If you get to 40 years of follow-up, half of these with benign MS will become disabled over the next 10 years.

Moving towards a more favourable outcome

Many will state that these figures are now out of date and there are newer and better figures, which show MS is a more benign disease. You are right, and there are several very good reasons for this. In population-based studies, the proportion of subjects with benign MS is greater than in hospital- or clinic-based studies; for example, in the Olmsted Mayo Clinic MS population, about 45% have benign disease at 15 years. The reason for this is that people with MS with benign disease often drop out of hospital follow-up, but still show up in population-based studies. 

The earlier diagnosis of MS, that is, identification of those who would not have been diagnosed in the past, is changing the definition of MS. For example, most people with a clinically isolated syndrome (CIS) are now being diagnosed as having MS. The wide use of DMTs is beginning to change the natural history of MS for the better; making sure that people with MS adopt a healthy lifestyle is another strategy that can be done in parallel. 

With currently available high-efficacy DMTs and the prospect of effective combination treatments in the future, the proportion of people with MS who experience normal ageing is set to increase. The blue areas illustrate the likely number of people with MS in each prognostic category.
With currently available high-efficacy DMTs and the prospect of effective combination treatments in the future, the proportion of people with MS who experience normal ageing is set to increase. The blue areas illustrate the likely number of people with MS in each prognostic category.
With currently available high-efficacy DMTs and the prospect of effective combination treatments in the future, the proportion of people with MS who experience normal ageing is set to increase. The blue areas illustrate the likely number of people with MS in each prognostic category.
With currently available high-efficacy DMTs and the prospect of effective combination treatments in the future, the proportion of people with MS who experience normal ageing is set to increase. The blue areas illustrate the likely number of people with MS in each prognostic category.

With currently available high-efficacy DMTs and the prospect of effective combination treatments in the future, the proportion of people with MS who experience normal ageing is set to increase. The blue areas illustrate the likely proportion of people with MS in each prognostic category.

The above figures illustrate what we aim to do with currently available high-efficacy DMTs (compared with older, lower efficacy treatments). We are simply trying to move you to the right, into a more favourable prognostic group. In other words, we want to make sure your MS is benign and that you reach old age with as healthy a brain as possible. Your brain reserve and cognitive reserve protect you from developing age-related cognitive impairment and dementia. MS reduces both of these reserves, which is why it is so important to protect them. With the prospect of effective combination treatments in the future, the proportion of people with MS who experience normal ageing is set to increase.

References

  1. Giovannoni G, et al. Brain health: time matters in multiple sclerosis. 2015, Oxford Health Policy Forum CIC.
  2. Miller DH, et al. Clinically isolated syndromes. Lancet Neurol 2012: 11:157–69.
  3. Weld-Blundell IV, et al. Lifestyle and complementary therapies in multiple sclerosis guidelines: Systematic review. Acta Neurol Scand 2022;145:379–92.
  4. Kappus N, et al. Cardiovascular risk factors are associated with increased lesion burden and brain atrophy in multiple sclerosis. J Neurol Neurosurg Psychiatry 2016;87:181–7.