B-Cell Therapy for Multiple Sclerosis

Medically Reviewed by Christopher Melinosky, MD on February 07, 2023
3 min read

B-cell therapy (also called B-cell depletion therapy) is a treatment for people with multiple sclerosis (MS). It targets cells called B cells that damage nerves in your brain and spinal cord.   

B-cell therapy isn’t a cure, but it can:

  • Ease symptoms
  • Help prevent relapses
  • Slow the course of your disease

B cells are a type of white blood cell. They make antibodies -- proteins that fight viruses and bacteria. B cells normally can’t cross from your blood into your brain or spinal cord. If you have MS, some B cells enter your brain and spinal cord and attack the myelin sheath that protects your nerves.

B-cell therapy uses drugs called monoclonal antibodies to attack these cells. These meds stick to the surface of B cells. This kills the cells, helps ease inflammation, and plays a part in slowing down nerve damage.

B-cell therapy might affect other parts of your immune system as they fight MS. That’s because B cells affect other immune cells called T cells. T cells usually kill viruses and bacteria. But when you have MS, B cells recruit T cells into your brain. There, they cause inflammation.

When your number of B cells goes down, your amount of T cells that cause inflammation goes down, too. At the same time, your level of something called regulatory T cells goes up. Regulatory T cells turn off inflammation. They may even help slow your immune system’s attacks on your body.

The FDA has approved two B-cell therapy drugs.

Ocrelizumab (Ocrevus) treats relapsing forms of MS, including:

  • Clinically isolated syndrome
  • Relapsing-remitting MS
  • Active secondary progressive MS in adults
  • Primary progressive MS in adults

It may lower relapses and slow the disease. You get ocrelizumab through an infusion at a hospital or clinic. This puts the medicine directly into your bloodstream. You’ll receive two doses, 2 weeks apart. Then you’ll get one dose every 6 months.

Ofatumumab (Kesimpta) is a shot you give yourself at home. Your doctor will teach you how. You'll have an injection once a week for 3 weeks, skip 1 week, and then inject one dose per month.

These drugs are new versions of the cancer med rituximab (Rituxan). Rituximab isn’t approved to treat MS, but doctors sometimes prescribe it as an "off-label" treatment. With rituximab, you'd get the medication through an IV in a doctor’s office. You’d get two doses, 2 weeks apart. Then, every 6 months, you’d have two more doses, 2 weeks apart.

Infusions sometimes cause an allergic reaction. Your doctor might call it an infusion reaction. If it happens, it's usually during your first dose.

You might have:

  • Itching
  • Rash
  • Nausea
  • Hives
  • Headache  

These symptoms are often mild but can be severe. You usually get your first dose of these medicines across two sessions to make it less likely that you'll have a reaction.

With any of these treatments, you could be more prone to infections like colds, bronchitis, and herpes. So it’s important to take steps to stay healthy.

Some researchers believe that these treatments can also give you a slightly higher chance of some cancers, especially breast cancer. But experts aren't sure of the connection.

In very rare cases, they may lead to progressive multifocal leukoencephalopathy (PML), a rare brain infection that can be fatal.

Before you try B-cell therapy, your doctor will go over all the possible side effects to make sure you know the risks and benefits of treatment.