Monoclonal Antibodies for MS Treatments

By Brett Drummond

What’s in a name?

I was recently asked a question:  “Why do all of the new MS drugs end in mab?  Does that mean something?”.  The answer is yes and it’s probably worth knowing.

The ‘mab’ at the end of new drug therapies refers to a class of treatments known as monoclonal antibodies.

What is a monoclonal antibody?

Antibodies, as you may know, form part of the immune system.  Antibodies are secreted by B cells and travel through the body to detect and neutralize foreign organisms (such as bacteria or viruses).  Their ability to do this is based on the fact that they recognize specific parts of the organism, which allows them to stick to that region.

Monoclonal antibodies are ones that arise from the same ‘parent’ cell.  This means that they all originate from the same source and are, therefore, all identical.

How can these be used in medicine?

As mentioned previously, the function of antibodies is to bind to, and block, specific molecules on invading organisms.  However, this property has also been harnessed for use in the treatment of diseases.  In this way, monoclonal antibodies are used to block a function in the body that is known to be harmful.

Let’s take a specific example.  Natalizumab (Tysabri) is a currently available monoclonal antibody used as a treatment for relapsing-remitting MS.  Natalizumab works by blocking the movement of T cells across the blood brain barrier (BBB).

As you can see in the image, T cells have a molecule on their surface called the α4 integrin.  This molecule is involved in helping the migration of the T cells into the central nervous system (CNS) through the BBB.  Natalizumab is a monoclonal antibody that binds to the α4 integrin, which blocks its function.  In this way, the antibody stops the T cells from entering the CNS, where they cause damage to the myelin.

Is this the future?

As you may have noticed, many of the upcoming treatments in MS are also ‘mabs’.  This includes ocrelizumab, daclizumab and ofatumumab.  All of these treatments will attempt to use the binding and blocking properties of antibodies to stop harmful processes in MS.