Rituximab

Rituximab (pronounced: ri-TUK-si-mab) is a potential treatment for MS.

Current phase of trial: phase II

Type of MS: relapsing remitting MS and progressive MS

How is it taken? Intravenous infusion into the bloodstream every two weeks

Research into: preventing damage caused by MS

• How does it work?
• Side effects
• How does it compare to current therapies?
• Further work
• When will it be available?

How does it work?

Rituximab is what is known as a monoclonal antibody and has been used to treat certain types of blood cancer (leukaemia and lymphomas) for several years. 

Rituximab targets a group of molecules called CD20 which are only found on a specialised type of immune cell called a B cell.

It is thought that these cells may contribute to damage of the myelin sheath in MS, and rituximab reduces the number of these cells.

Rituximab in relapsing remitting MS

In February 2008 results of a one year phase II clinical trial involving 104 people comparing the effectiveness of rituximab to a placebo treatment were announced.

Participants taking rituximab had a reduced number of new MRI lesions compared to the placebo control group over a period of one year.

They also had a 50% reduction in relapse rate compared to people taking a placebo (dummy) treatment. This remained constant over the one year period.

Rituximab in primary progressive MS

A phase II/III trial of rituximab involving 439 people with primary progressive MS reported back in 2009.

These results are not yet published in a peer reviewed scientific journal but have been described in a press release.

The trial compared rituximab to a placebo treatment but showed that rituximab was not effective.

Rituximab was found to be relatively safe in people with primary progressive MS with most side effects relating to infusion reactions and an increase in infections.

Trial investigators have suggested that better patient selection in future (choosing younger patients with signs of inflammation in the brain) may improve outcomes.

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Side effects

Rituximab has been associated with severe side effects such as injection site reactions and progressive multifocal leukencephalopathy (a potentially fatal infection of the brain that has also been associated with Tysabri), though these have not occurred in studies to do with MS.

The most common side effects in studies in MS to date were reactions to the infusion and infections.

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How does it compare with current therapies?

These studies compared rituximab to a placebo (dummy treatment); therefore it isn’t possible to compare rituximab with other available therapies.

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Further work

A phase I trial testing the safety of rituximab in 20 people with neuromyelitis optica (a rare condition with some similarities to MS) was due to finish in December 2009 (clinicaltrials.gov identifier: NCT00501748).  Results of the trial have not been reported yet.

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When will it be available?

Rituximab is already licensed for use in certain types of blood cancer, but not
for MS. Further trials will be necessary before a licence can be sought in the UK.

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