Infusion-based therapies

Ocrelizumab (Ocrevus). This is the first drug approved by the FDA to treat both relapsing MS and primary progressive MS. Not only has it been shown to reduce relapses, but it slows disease progression.

Ocrelizumab is given as an IV infusion initially twice in two weeks. After that, the infusion is given every six months. Infusion reactions, such as a headache, rash, nausea and fever, are common. Your doctor might recommend that you be given a corticosteroid and an antihistamine before infusion to help prevent reactions.

People with hepatitis B shouldn't take ocrelizamab.

Natalizumab (Tysabri) is a humanized monoclonal antibody that acts by reducing the migration of immune cells across the blood-brain barrier into the central nervous system. This medication is given intravenously every four weeks.

Natalizumab is effective against relapsing MS, reducing the relapse rate by about two-thirds. However, it is associated with a small but important risk of a serious brain infection known as progressive multifocal leukoencephalopathy (PML).

People who take natalizumab must be closely monitored for symptoms of PML, which include progressive weakness and visual or cognitive changes that may not be reversible.

A person's ongoing PML risk is assessed using factors such as:

• The presence of antibodies to the John Cunningham virus on blood testing
• Previous treatment of immunosuppressive drugs, such as mitoxantrone
• Taking natalizumab longer than two years

Alemtuzumab (Lemtrada). This drug helps reduce relapses of MS by targeting a protein on the surface of immune cells and depleting white blood cells. This effect can limit potential nerve damage caused by the white blood cells, but it also increases the risk of infections and autoimmune disorders.

Treatment with alemtuzumab involves five consecutive days of drug infusions followed by three days of infusions a year later. Infusion reactions, such as a headache, rash, nausea and fever, are common with alemtuzumab.

Due to the risks associated with alemtuzamab, the FDA recommends extensive screening before using the drug. It's only available from registered providers, and people treated with alemtuzumab must be registered in a special drug safety monitoring program.

Mitoxantrone. Mitoxantrone is an immunosuppressive drug that's approved for treating rapidly worsening relapsing MS, and the only medication approved to treat secondary progressive MS, an advanced form of relapsing MS.

It's given intravenously and use is limited to a maximum of two years because of important side effects, including damage to the heart muscle. It is also associated with the development of blood cancers, such as leukemia. Due to these side effects and the availability of other therapies, mitoxantrone is used only in exceptional circumstances.