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.

UCB Pharma have told the SMC they plan to apply in the future. More information on the SMC’s assessment can be found on their website.

The National Institute for Health and Care Excellence (NICE) are reviewing the submission for Zilbrysq, with a decision expected in the first half of 2025.

In July 2024, as part of the assessment, NICE released draft guidance which said Zilbrysq should not be recommended. This is a common part of the assessment period, and the decision could change as the assessment process progresses.

The draft guidance triggered a consultation, which gave charities and the public an opportunity to provide comments and feedback on the draft guidance. A meeting took place in early 2025 to discuss this feedback and any further evidence submitted by UCB Pharma. We are waiting to hear the outcome of this meeting.

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• providing feedback on the draft guidance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: 18/02/2025