Zilbrysq

Pharmaceutical company: UCB Pharma

To move, signals are sent from the brain, down specialised cells called nerves to the muscle. Acetylcholine receptors play a key role in passing the signal from nerve cells to the muscle. In myasthenia gravis, the immune system attacks the acetylcholine receptors. This means the nerve cells struggles to send strong signals to muscles, leading to muscle weakness.

When the immune system attacks the acetylcholine receptors it activates a part of the immune system called the complement system. This promotes inflammation. Normally this inflammation can help the body fight off infections, but in myasthenia gravis it can lead to damage to muscles. Zilbrysq works by blocking the activation of the complement system.

Zilbrysq come as a liquid and is administered through an injection under the skin (subcutaneous injection).

Zilbrysq may be available through an early access scheme. For more information, please get in touch with your clinician.

In June 2025, the National Institute for Health and Care Excellence (NICE) has confirmed Zilbrysq will not be funded. This means it will not be available on the NHS in England, Wales and Northern Ireland. While NICE acknowledged that Zilbrysq can “improve symptoms and people’s ability to carry out their normal activities”, NICE decided that the benefit it offers isn’t currently enough to justify the cost to the NHS. Read about NICE’s assessment.

A separate assessment will take place in Scotland to decide if it should be available on the NHS. UCB is currently in discussions with the relevant authorities. More information on the SMC’s assessment can be found on their website.

We believe this is an unacceptable outcome for people living with myasthenia gravis. It denies access to a treatment that has the potential to make a real difference to people’s daily lives and reflects broader issues in how treatments for rare and complex conditions are assessed. We’re looking at how we can best support the myasthenia gravis community following this decision. This includes working with clinicians, partner organisations, and people living with the condition to understand the impact and explore what can be done to help improve access in the future.

We will also continue to work alongside Myaware to ensure the voices of those affected are heard throughout the process in Scotland.

We are working in partnership with the charity Myaware to make sure the experience and views of the myasthenia gravis community are heard throughout the NICE assessment process.

This has included:

• nominating and supporting two members of the community to share their experience of myasthenia gravis and Zilbrysq
• providing feedback on the draft guidance

Zilbrysq was tested in the phase 3 RAISE trial. 174 participants, aged between 18 – 74 years old, with a myasthenia gravis activities of daily living (MG-ADL) score of at least six took part in the trial. The MG-ADL score measures the impact of the condition on a person’s daily function, such as talking, swallowing and getting up from a chair. The score can range from zero to 24, with a lower score means symptoms are less severe.

Participants were randomly assigned to receive Zilbrysq (86 participants) or placebo (dummy drug, 88 participants). All participants tested positive for the antibodies which attack acetylcholine receptors. Zilbrysq was found to be safe. After 12 weeks, more participants who received Zilbrysq showed improvements in the MG-ADL scale, compared to those who received the placebo.

73% of participants who received Zilbrysq had a reduction of at least three points, compared to 46% of participants who received the placebo. A reduction of two points is considered to be beneficial (clinically meaningful) to people living with the condition. This may mean people with the condition are able to complete daily tasks they were unable to before, such as brush their hair or get up out of a chair without assistance.

Long-term data is being collected in the RAISE-XT trial.

Last updated: 26/06/2025