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SMA Gene Therapy Service

SMA Gene Therapy

In April 2021, NHS England announced that four centres in the UK would be commissioned to provide a gene therapy called Zolgensma® (onasemnogene abeparvovec) to children with a progressive muscle disorder called Spinal Muscular Atrophy (SMA). The sites were:

  • Sheffield Children’s Hospital
  • Bristol Royal Hospital for Children
  • Evelina Children’s Hospital, London
  • Royal Manchester Children’s Hospital.

Please see below for information on the treatment and how children can be referred to our service.

Information for referring clinicians

What is spinal muscular atrophy?

Spinal muscular atrophy (SMA) is a rare genetic condition. It typically affects a gene called the Survival of the Motor Neurone gene 1 (SMN1), although rarer versions affecting other genes also occur. In most types of SMA, both copies of the SMN1 gene are faulty and cannot work properly. As a result, the nerves in the spine carrying messages from the brain to muscles become injured over time. People with SMA become weaker and find moving hard.

A second gene, called SMN2, tries to make up for the faulty SMN1 genes, but it cannot do this 100%. So, SMA is a spectrum – some people are affected more than others.

SMA is split up into different types:

  • SMA Type 1 – weakness starts either around the time of birth up to six months of age. Children are not able to sit without help. In the past, although some children used to live into later childhood with help and support, a lot of children used to die within a few months of diagnosis. The good news is that things have changed a lot in the last few years and the future looks brighter.
  • SMA Type 2: The symptoms in SMA Type 2 are usually clear between 7 and 18 months of age. Children can sit when they are at their best, but they cannot stand without treatment. Over the next few years, they become weaker and lose the ability to sit. They find breathing harder and may require some help with physiotherapy and / or machines to help them cough and breathe. They may get chest infections.
  • SMA Type 3: People with this form of SMA are able to walk before the weakness begins.
  • SMA Type 4: Symptoms being in adulthood with weakness in the arms and legs, and difficulty walking.

You can find more information about SMA from the charity SMA-UK.

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What treatments are available for SMA?

Up until the mid 2010’s, there was no medicine to help people with SMA. Treatments were focussed at helping children move and breathe, but there was no cure. Sadly, many children died young.

In the mid 2010’s, a drug therapy called Nusinersen (Spinraza) became available in the UK. This is a medicine that is injected into the spine and encourages the SMN2 genes to work better. Nusinersen halts or slows the progressive muscle weakness caused by SMA. Although it works well for many children, it is not a cure. Children need injections into their spine for the whole of their life. This is not an easy thing to do, and is unpleasant. Some children develop a curve in their spine because their muscles are weak, and this makes the process of giving nusinersen harder. You can find more information on nusinersen on the SMA-UK website.

In 2021, a new drug called Zolgensma® (onasemnogene abeparvovec) became available in the UK. This is a gene therapy that uses a virus to insert the missing SMN1 gene into a child’s body. Research studies show it can stop the gradual muscle weakness happening.

Zolgensma® is injected into the veins once through a drip. After that, a child needs regular follow-up to look for side effects, such as problems with the liver, kidneys, and heart.

The medicine is very expensive – nearly £2million – so it is important that you agree to come to all of the follow-up appointments and don’t forget to come for the treatment.

Zolgensma® can only be given in one of four UK centres. If you live in a different part of the UK from the gene therapy centres, your child can still access the treatment but you will need to travel and stay near the centre for a couple of weeks until it is safe for your child to go home. Please talk to your neurologist about where your local centre is and ask them if your child is eligible for treatment.

If that centre is busy, they will find another one that is able to give the treatment. This may be further from your home.

Currently, the following children may be considered for Zolgensma®:

  • Children under 13 months of age diagnosed with SMA type 1 or who are identified as pre-symptomatic of having SMA (and have three or less copies of the SMN2 gene) who are not on any other SMA drug treatment.
  • Children with SMA type 1 or pre-symptomatic of having SMA under 13 months of age who are on other SMA drug treatment.

Some of these patients will need to be discussed in a national meeting, and we cannot promise that every child will be allowed to have it.

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What will happen if your child is referred to Sheffield Children’s for Zolgensma®?

 We hope to have an information leaflet ready soon for families. Until we do, the process will be as follows:

  • Your local team will carry out some tests, including blood tests. If they can, they will also organise a heart scan and heart tracing, and a physiotherapy assessment. These results will be sent to Sheffield Children’s before we can accept the referral.
  • You will have an appointment with the team, who will explain what you can expect. This may be a video appointment or face-to-face in Sheffield, depending on the child’s circumstance.
  • We will need an updated weight of your baby (weighed naked as this is required for correct drug dosage).
  • You will be admitted to our High Dependency Unit (HDU), usually on a Monday. This is “assessment day”. Your child will see a physiotherapist, the doctors, and there will be some more blood tests. Your child will start some steroids to suppress their immune system. This will hopefully reduce the risk of a reaction to the treatment and will be given for at least one month, maybe longer.
  • The next day, your child will have Zolgensma®. Your child will need two drips into their veins, and the medicine will be given over an hour. They will need to stay in hospital until Thursday for observation and blood tests.
  • After the treatment, you will need to be careful when you are changing your child’s nappy or are in contact with their wee or poo. You will need to wear gloves, wash your hands thoroughly, and put nappies in at least two bags before you through the out. You will need to do this for at least 30 days. We will talk you through this.
  • On day four (usually a Thursday), if you live within 30 minutes of the hospital, you will be likely to go home if everything has gone well. If you live further away, we will provide you with some alternative accommodation near the hospital.
  • Your child will have regular appointments to look for side effects of the drug over the next week or so. If you have stayed local to Sheffield and your child remains well, you will be here for around two weeks in total.
  • Over the next few weeks and months, your child will need to have regular follow-up appointments and bloods to check they are OK. Some of these appointments will be in your local hospital. Others will be over video, so you don’t have to travel to Sheffield. You will need to come to Sheffield Children’s at the end of the first, second and third month to check everything is OK and for the physiotherapist to review your child.
  • After the three month appointment, we will discuss with your local team whether follow-up can happen locally or not.

We will keep you up to date about where and when your child will be seen and when they will need blood tests.

The main side effects of Zolgensma® are a temperature or flu-like illness in the first few weeks. Other children have problems with their liver or cells in the blood called platelets, which help it clot. If someone gets these side effects, we may need to increase the dose of steroids, or keep them going for more than a month. They may need more blood tests to check everything is OK.

We will also keep an eye on your child’s heart function, as there have been some concerns of Zolgensma® in relation to problems with the heart. Please be reassured though that serious problems are very, very rare.

For more advice on Zolgensma®, please see the SMA-UK website.

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