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Ofatumumab (also known as Arzerra) is an injection or infusion being developed for relapsing MS.

Current phase of trial:
Phase 3
Type of MS:
Relapsing MS

Phase 2 trials were completed by GlaxoSmithKline (GSK). Novartis have now purchased the rights to ofatumumab in order to carry out late stage trial.

Find out more about ofatumumab

How does ofatumumab work?

Ofatumumab is an antibody, just like those found in the immune system (where antibodies help fight infection). It is currently used to treat lymphocytic leukaemia but is being tested as a treatment for relapsing remitting MS.

Ofatumumab has been designed to bind to the surface of a type of immune cell (called a B cell) and reduce their numbers. These cells are thought to be one of the immune cells that attacks myelin in MS.

How is ofatumumab taken?

Ofatumumab is given as an injection under the skin (subcutaneous) or as an infusion.

In the large phase 3 trials, ofatumumab is injected under the skin every four weeks.

Latest research


Two phase 3 trials are testing if ofatumumab injections can reduce relapse rates and slow worsening of disability more effectively than the licensed treatment Aubagio (terifluorimide): ASCLEPIOS I and II. The trials will each involve approximately 900 people with relapsing MS. They began recruiting in September 2016 and are due to finish in May 2019.

Earlier research

The MIRROR trial

This phase 2 trial involved 232 people with relapsing MS. Researchers reported that higher doses of ofatumumab reduced new brain lesions by up to 90% compared with placebo in the 12 weeks following treatment. Researchers did not report any unexpected safety findings.

The trial tested three doses of ofatumumab (3mg, 30mg and 60mg). All doses were taken as an injection under the skin.

Phase 2 trial

This trial tested the benefits of different doses of an ofatumumab infusion (100mg, 300mg, or 700mg), and involved 38 people with MS.

Ofatumumab significantly reduced B cell numbers, and all doses of the treatment almost completely suppressed the development of new MRI lesions.

What are the side effects of ofatumumab?

Ofatumumab has not been widely tested in people with MS. In these phase 2 studies the most frequent side effects have been infections related to the injections.

How does ofatumumab compare with current therapies?

Ofatumumab has not yet been directly compared with different disease modifying treatments, so it isn’t possible to draw conclusions about its relative effectiveness at this time.

When is ofatumumab likely to become available?

Ofatumumab is already licensed for other conditions but is not licensed for MS.

We will need to wait for the results of the two phase 3 trials to be able to assess the effectiveness of ofatumumab in a larger number of people. This could take several years.