Being diagnosed with multiple sclerosis (MS) is seen as a life sentence, as the disease can seriously affect a sufferer's motor skills and cognitive abilities, but new hope might be on the way. This week, the US Food and Drug Administration (FDA) has approved a new drug, called ocrelizumab, which fights MS by targeting the body's B cells and is the first to have an effect on the more severe form of the disease.

Like electrical wires, the nerve cells in the body are coated with a layer of insulation called myelin, but in cases of MS, the immune system mistakes these cells for invading pathogens and attacks them. As the protective sheaths are damaged, the nerves essentially "short circuit," leading to impairments of a patient's motor skills, visual acuity, and cognition. In its most common form – called relapsing-remission MS – symptoms will flare up on a semi-regular basis, but an unlucky 10 percent of sufferers experience primary progressive MS, where symptoms steadily worsen without letting up.

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There's no known cure for the disease, but plenty of promising research is underway. The tactics being used to fight MS include clearing iron blockages in the brain's blood vessels, training the immune system to get used to myelin, blocking inflammation-causing proteins or "rebooting" the immune system altogether.

Historically, MS research has focused on dealing with T cells, the ground troops of the immune system. Previous studies on mice showed that a condition similar to MS could be transferred to other animals by introducing T cells from a stricken mouse to a healthy one, but the find didn't carry across to human forms of the disease.

The UCSF team instead focussed on a separate type of immune cell, called B cells, which lead researcher Stephen Hauser MD and his colleagues had established as playing a key role in the disease. The majority of these cells live deep inside the brain, but about 2 percent circulate through the blood and cause inflammation in the nervous system of MS sufferers.

UCSF scientist Stephen Hauser led the research team behind the development of ocrelizumab (Credit: Steve Babuljak)

With a new target in their sights, the researchers developed ocrelizumab (also known by its brand name Ocrevus), and in recent clinical trials, the drug was found to effectively destroy these rogue B cells for several months at a time. When tested against interferon beta-1a, the current standard for treating relapse-remitting MS, ocrelizumab was found to reduce the annual relapse rates by 47 percent, reduce disability by 43 percent and shrink brain lesions by 95 percent.

Even more impressively, the new drug shows promise in slowing down primary progressive MS. The researchers suspect that this form of the disease could be caused by the 98 percent of B cells hiding away in the brain, which makes it much harder to treat. The effects were admittedly small, but the fact that this marks the first treatment that's had any effect whatsoever on primary progressive MS is encouraging.

"The availability of a highly effective and well-tolerated treatment means that people at the dawn of their MS can be treated with a therapy that will essentially completely block the inflammation in myelin that causes relapses and remission," says Hauser. "And we are optimistic that by doing so, the outlook over many years will be even more favorable than it is today. My hope is that ocrelizumab will make a life-changing difference for many hundreds of thousands of people with MS today, and many more who may develop MS in the future."

The results of the trials were published in the New England Journal of Medicine.

Source: UCSF

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