The Medicines and Healthcare products Regulatory Agency (MHRA) has today (9 June 2026) authorised the medicine nipocalimab (Imaavy) to treat adults and adolescents aged 12 years and older with generalised myasthenia gravis (gMG).
Myasthenia gravis is an autoimmune disease in which the immune system (the body’s natural defences) disrupts communication between nerves and muscles, causing muscle weakness and tiredness. It most commonly affects the muscles that control the eyes and eyelids, facial expressions, chewing, swallowing, and speaking, but it can affect most parts of the body.
In patients with the condition, immunoglobulin G (IgG) autoantibodies attack and damage certain proteins on the nerves called acetylcholine receptors. Because of this damage, the nerves are not able to make the muscles contract as well as normal, leading to muscle weakness and difficulty moving.
Nipocalimab binds to a protein in the body called the neonatal Fc receptor (FcRn). This binding reduces levels of IgG autoantibodies – immune system proteins that mistakenly attack the body’s own tissues. By doing this, the medicine can improve the ability of muscles to contract and reduce the symptoms of the disease and their impact on daily activities.
Julian Beach, MHRA Executive Director, Healthcare Quality and Access, said
“Myasthenia gravis can significantly affect a person’s ability to carry out everyday activities, and today’s authorisation provides an additional treatment option for adults and adolescents living with this condition.
“We have assessed the evidence for nipocalimab and are satisfied it meets our standards for safety, quality and effectiveness. As with all authorised medicines, we will continue to monitor its safety closely.”
Nipocalimab is given as an infusion (drip) into a vein every 2 weeks.
This authorisation is supported by evidence from a main study of 153 adults with gMG, for who standard treatment was insufficient, and a supportive study of 8 adolescents aged 12 to 17.
The most common side effects of the medicine (which may affect more than 1 in 10 people) include high level of lipids (fats) or cholesterol in the blood, decreases in the level of ‘albumin’ (a protein) in the blood, muscle spasms, and swollen hands, ankles or feet (peripheral oedema). For the full list of side effects, see the package leaflet.
As with any medicine, the MHRA will keep the safety and effectiveness of nipocalimab under close review.
Anyone who suspects they are having a side effect from this medicine are encouraged to talk to their doctor, pharmacist or nurse and report it directly to the 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
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The new marketing authorisation was granted on 9 June 2026 to Janssen-Cilag Limited.
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This application was approved under the International Recognition procedure (IRP).
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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.
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For more information about Myasthenia gravis, visit Myasthenia gravis – NHS
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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.
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The MHRA is an executive agency of the Department of Health and Social Care.
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