When you have multiple sclerosis (MS), your immune system works against you. Left unchecked, immune cells attack the protective coating surrounding nerve fibers. Doctors used to think your immune T cells were to blame. Antibody-producing immune B cells are considered innocent bystanders.
That’s changing as scientists begin to realize that existing MS treatments work in part by changing what B cells are doing. Is it possible to treat MS by directly targeting B cells?
Doctors already have a way to do this: an antibody-based treatment called rituximab, which is used to fight a type of cancer called B-cell lymphoma. A 2008 study showed that rituximab did help people with multiple sclerosis. After 48 weeks, people in the study had fewer brain lesions and avoided recurrence.
The FDA approved a drug similar to rituximab called ocrelizumab (Ocrevus) in 2017 for the treatment of MS. You get it by IV every 6 months. In 2020, the FDA approved another drug called ofatumumab (Kesimpta) that works in the same way. You shoot at home once a month. Doctors also sometimes use rituximab for MS.
No matter which one you take, the goal is to reduce the number of B cells you have. When it works the way it should, you don’t notice anything right away.
“The real benefits we’re looking for are not immediate,” said Ari Green, MD, a neuroscientist at UCSF Health. “It will take years or even decades. The goal is to prevent long-term disability.”
When to Consider B Cell Therapy
B cell therapy prevents disability over time by preventing new damage to your nervous system. It cannot repair damage that already exists, but it can prevent future damage and attacks.
In the first few months to a year, you should notice fewer recurrences of your MS symptoms, Green said. The therapy did a better job of preventing new brain lesions from forming.
So, if you’re newly diagnosed, should you get B cell therapy?
“In the MS world, there’s a debate about getting someone new to the disease on a drug that’s thought to be highly effective rather than starting one of the earlier treatments,” said Julie Fiol, RN and vice president of health care access for the National MS Society .
Some doctors may try older medications first to see if they help. This is partly because they have been around longer and therefore have a wider safety record. If you relapse or worsen, you can upgrade to B cell therapy.
“It’s a step-by-step approach,” said Eric Seachrist, MD, a neurologist at West Virginia University Hospital who has multiple sclerosis and is receiving B-cell therapy himself. “You start with the safest but least effective drug, and if it relapses, you can increase.”
But he said the newer way of doing things is to use the strongest drug from the start. It was his advice to his patients, and it was what he chose for himself. The goal is to prevent disease activity and irreparable damage, and hopefully help keep the disease from getting worse.
“Initiating B-cell therapy can lead to better disease control in the first place and later to delay or prevent secondary progression,” Seachrist said. “But we don’t know the long-term effects of taking super-strong immune-modulating drugs on the body.”
While many physicians are now recommending a B-cell therapy-first approach, there are still things to consider, Fiol said. Most people do well with B cell therapy. But because it wipes out parts of your immune system, it increases the risk of infection. This treatment also makes any vaccines you take less effective. Because these drugs have not been around for a long time, the effects of depleting B cells for decades are unclear.
Fiol says there is no “one size fits all”. Before deciding on MS treatment, you should discuss the risks and benefits of each option with your doctor, she says.
How long will you need B cell therapy?
It’s unclear whether B-cell therapy will last forever. But doctors did get some clues from its early use for rheumatoid arthritis.
“We know from the arthritis field that if B cells are depleted for a period of time and then treatment is stopped, eventually the disease will relapse,” Green said. “We think the same goes for MS.”
But, he said, this may only be true if you’ve been on B-cell therapy for a relatively short period of time. What will happen in the long run is less clear. Fiol points out that your immune system naturally changes as you age. As a result, MS becomes less active over time.
“In most cases of MS, the highest disease activity in terms of relapses that cause inflammation occurs early, about the first 5 to 10 years,” Seachrist said. “So maybe you just need a period of highly aggressive treatment, and then you can de-escalate to something that’s gentler on the body. That’s an open question.”
B-cell therapies available today are sure to kill more cells than are needed to control MS, Green said. He predicts that in the future, treatments may become more specific. Some treatments currently under study also affect B cells in other ways that may prove to be less risky.
For now, he said, you should expect to use B-cell therapy for many years, most likely a decade or more. But that may change as doctors learn more and new treatments become available.