Key messages

• The evidence is very uncertain about the effects of the medication, rituximab, on symptom (disease) severity, ability to do daily activities and serious harms in adults with myasthenia gravis.

• Rituximab treatment makes little to no difference to the ability to reduce the steroid dose to below 10 mg per day, but probably results in a large reduction in relapse requiring rescue therapy (such as treatment with intravenous immunoglobulin or plasma exchange) nine months or more following treatment.

• Further studies are needed to better understand the effects of rituximab in treating all types of myasthenia gravis.

What is myasthenia gravis, and how is it treated?

Myasthenia gravis is an autoimmune condition in which the body makes antibodies (proteins produced by the immune system to usually protect the body from infections) that affect the function of the junction between nerves and muscles. This means that messages struggle to get across to the muscles, leading to muscle weakness. People may experience a range of symptoms including double vision, drooped eyelids, problems speaking, chewing or swallowing, breathlessness, or limb weakness. Many patients will need medications that reduce the immune response to help bring these symptoms under control. Rituximab is a treatment that dramatically reduces the number of B cells (one component of the immune system).

What did we want to find out?

We wanted to know whether rituximab was better than no treatment, placebo (dummy pill) or an alternative treatment. We also wanted to find out if it was associated with any harmful effects.

What did we do?

We searched for studies that compared rituximab to no treatment, to a placebo, or to alternative treatments for adults with myasthenia gravis. Studies had to randomly choose which people received the medication and ensure that people did not know the treatment they were receiving. We compared and summarised the study results, and rated our confidence in the evidence.

What did we find?

We found two studies involving 99 people in Sweden and the USA.

• In the long term (over nine months), rituximab may reduce symptom severity and improve functional ability, but the evidence is very uncertain.

• Rituximab results in little to no difference in the chance of bringing the steroid dose down to 10 mg or less per day.

• Rituximab probably results in a large reduction in relapse requiring rescue therapy nine months or more following treatment. Based on results from 98 people, we estimate that 220 out of 1000 people on rituximab would have a relapse requiring rescue therapy, compared to 490 out of 1000 people who received a placebo.

• Rituximab may reduce serious unwanted effects, but the evidence is very uncertain (298 out of 1000 people on rituximab may experience a serious unwanted effect compared to 367 out of 1000 people who receive a placebo).

What are the limitations of the evidence?

There are not enough studies to be certain about our findings. The studies mainly looked at people with antibodies to the acetylcholine receptor (AChR), and did not include people with antibodies to muscle-specific kinase (MuSK). MuSK myasthenia is more likely to respond to rituximab than AChR myasthenia due to the type of immune cells which produce the antibodies.

How up to date is this evidence?

Both studies were published in 2022. The search is up-to-date as of November 2024.