Drug Treatments for Adults who have 5q SMA – Type 1, 2 or 3.
Drug Treatments for Adults who have 5q SMA – Type 1, 2 or 3.
This page provides short answers to the common questions adults have about the two NHS-funded drug treatments. We use the names of the treatments that are most commonly used by the SMA community:
- Spinraza
- Risdiplam
Decisions about treatment can be complex.
Each person’s situation and circumstances is different.
Your discussion with your clinical team will be much more detailed.
Drug Treatments for adults in England (pdf) > is our more detailed reference publication.
Your questions answered
People with SMA do not have enough of a protein called ‘survival motor neuron’ (SMN) protein. This protein is essential for the nerve cells, known as motor neurons, that help control muscles. Motor neurons are found in the brain and spinal cord, and they make contact with muscles.
The SMN protein is made in our cells from two genes, SMN1 and SMN2. People who have SMA have:
- two ‘altered’ copies of the SMN1 gene. These are unable to produce enough SMN protein to have healthy lower motor neurons.
- a number of copies of the SMN2 gene. This is often called the back-up gene. It mostly produces a short SMN protein that does not work as well as a full-length protein.
SMN protein is most important for motor development early in life. Increasing SMN protein later in life cannot restore lost motor skills.
Researchers know that adults lose their motor abilities more slowly over time. But the condition is still progressive. More SMN protein in adulthood may prevent a decline in motor skills and stabilize the condition.
Both treatments aim to increase the amount of stable SMN protein that SMN2 can provide.
Spinraza
This is a small piece of genetic material (a synthetic antisense oligonucleotide). It targets the ‘back-up” SMN2 gene. It makes the gene produce more usable full-length SMN protein.
Risdiplam
This is a small molecule drug. It targets the ‘back-up’ SMN2 gene. It makes the gene produce more usable, full-length SMN protein.
If your clinician does not already have genetic test results that confirm you have 5q SMA they will:
- arrange for you to have a blood test. This will confirm if your SMA is caused by alterations in the SMN1 genes. It will also show how many SMN2 gene copies you have.
- ask you when your symptoms started and how your condition has progressed.
This is so they can work out if your clinical diagnosis is Type 1,2, 3 or 4.
Currently people who have a diagnosis of SMA Type 4 may not be prescribed one of these treatments. Symptoms will have started after age 18 years. People who have SMA Type 4 will have between 4 and 6 SMN2 copy number.
Other rarer forms of SMA with different genetic causes would not respond to either of these treatments.
Spinraza
This is given by lumbar puncture. A needle is inserted through the skin into the space between the back bones of the spine (vertebrae) into the fluid that flows in and around the brain and spinal cord (cerebrospinal fluid -CSF). Doctors usually use a local anaesthetic such as ‘numbing cream’ when they do this. If a sedative or general anaesthetic is needed, the doctor will decide if this is safe for you or if a different treatment should be considered.
The total length of time the procedure takes will vary. The injection itself takes between one and three minutes.
‘Loading doses’ are given to get the level of the drug to an effective concentration within the CSF. These are:
- On the first day of treatment, day 0
- Then around day 14, day 28 and day 63
- There should always be at least 14 days between doses.
Once the loading doses have all been delivered, there are then maintenance doses every 4 months to maintain the drug concentration level in the CSF.
Risdiplam
This is given as a liquid at home. It is taken daily after a meal, at approximately the same time each day. It is given by mouth (orally) or feeding tube, using the syringe that comes with it. It is provided in a bottle in a box that must be kept in the fridge. It comes with instructions about how long it is safe to keep it out of a fridge and what is the allowed maximum temperature.
In all cases you would have regular contact with your clinical team to check how you are reacting to your treatment.
Both treatments reach the motor neurons to treat SMA.
Both treatments reach other types of cells. The extent of this, and any potential benefits, are unknown.
Your clinical team will discuss the possible risks and benefits of each treatment with you. To have Spinraza it must be technically possible and clinically safe for you to have an injection into your spine (an intrathecal injection).
You can read more on this topic if you follow the links at the top of this page. Each treatment also has a detailed Patient Information Leaflet:
There are no clinical trials or studies that directly compare the effect of these treatments.
- Spinraza has been tested in clinical trials in humans since 2011.
- Risdiplam has been tested in clinical trials in humans since 2015.
In these trials, both treatments have been consistently shown to have a well understood safety profile and to be well-tolerated.
When compared to no treatment, both treatments have led to clinically meaningful improvements in muscle function.
The long-term outcomes and the specific outcomes for any individual are uncertain.
Your clinical team will know about the clinical trials for each treatment. They will have ‘real world’ information that is being collected and discussed all the time.
In July 2024, we asked the pharmaceutical companies how many people had been treated across the world:
Biogen told us their latest update was that more than 14,000 people had been treated with Spinraza.
Roche told us that at the end of March 2024, more than 15,000 people had been treated with Risdiplam.
Version 2
Author: SMA UK Information Production Team
Published: July 2024
Review due: May 2025
Links last checked: July 2024
The information provided in this guide, on our website, and through links to other websites, is designed to complement not be a substitute for clinical and professional care and advice.
For more detail about how we produce our information, please see these pages.
If you have any feedback about this information, please do let us know at: information@smauk.org.uk