The Medicines and Healthcare products Regulatory Agency (MHRA) approved tofersen (Qalsody) on 22 July 2025 to treat adults with amyotrophic lateral sclerosis (ALS) caused by mutations in the SOD1 (an enzyme called superoxide dismutase 1) gene – a rare, inherited form of motor neurone disease (MND).
ALS is a progressive condition that affects nerve cells in the brain and spinal cord. This leads to muscle weakness, including the muscles needed to breathe and swallow. Tofersen works by reducing levels of the toxic protein produced by the SOD1 gene, which damages nerve cells.
The approval was granted via the International Recognition Procedure (IRP).
Tofersen is given by lumbar puncture (injection into the lower spine) at regular intervals by a healthcare professional.
Common side effects seen in clinical studies include headache, back pain and tiredness. In rare cases, more serious side effects have occurred, including inflammation of the spinal cord or optic nerve, and increased pressure around the brain.
As with any medicine, the MHRA will keep the safety and effectiveness of tofersen under close review.
Anyone who suspects they are having a side effect from this medicine is encouraged to talk to their doctor, pharmacist or nurse and report it directly to the MHRA Yellow Card scheme, either through the website (https//yellowcard.mhra.gov.uk/) or by searching the Google Play or Apple App stores for MHRA Yellow Card.
Notes to editors
- The approval was granted on 22 July 2025 to Biogen Netherlands B.V.
- More information on the International Recognition Procedure can be found here
- More information can be found in the Summary of Product Characteristics and Patient Information leaflets which will be published on the MHRA Products website within 7 days of approval.
- The Medicines and Healthcare products Regulatory Agency (MHRA) is responsible for regulating all medicines and medical devices in the UK by ensuring they work and are acceptably safe. All our work is underpinned by robust and fact-based judgements to ensure that the benefits justify any risks.
- The MHRA is an executive agency of the Department of Health and Social Care.
- For media enquiries, please contact the newscentre@mhra.gov.uk, or call on 020 3080 7651.
