Primary Mediastinal B-Cell Lymphoma: CAR T Side Effects

Medically Reviewed by Neha Pathak, MD on March 06, 2020
4 min read

Even though it’s one of the latest and greatest cancer treatments, CAR T therapy still has its side effects. They’re often mild, but they can be serious and affect your heart, kidneys, and brain.

That may sound scary, but Caron Jacobson, MD, medical director at the Dana-Farber/Brigham and Women’s Cancer Center, says, “Remember that the vast majority, 99-plus percent of [people], have a full recovery.”

So even with severe side effects, you almost always bounce back.

That’s a big deal. It’s good to know what problems might arise, but you also want to trust that your doctor can treat them. 

Often one cycle of chemotherapy is given as part of CAR T-cell treatment for primary mediastinal B-cell lymphoma (PMBL).  Common side effects include stomach upset and fatigue.

In the first 3 weeks after CAR T therapy, especially that first one, doctors keep a very close eye on you.

“Generally speaking, we want them in the hospital,” says Loretta Nastoupil, MD, a director at the MD Anderson Cancer Center.

That’s because if you get serious side effects, you’ll likely see them early on. You usually stay in the hospital for at least 7 days after treatment. 

Cytokines are chemicals that help direct your immune system. As CAR T cells attack your cancer, your cytokine levels go up. As that happens, you may get CRS. It might cause only mild symptoms, like a fever.

And that’s good news because it means your new T cells are working. But it can get serious, too.

When it’s mild, Jacobson says, “That would be sort of like a flu-like illness. They’d have fevers. They’d have fatigue, maybe headaches, maybe body aches. They could have slightly low blood pressure, but that would come up with some gentle IV fluids.

"So we keep them hydrated, give them Tylenol for the fevers, and check for infections.”

If you have a low white blood cell count or other signs of infection, you get antibiotics.

When it’s serious, CRS can cause severe problems in your heart, kidneys, lungs, and other organs. Your blood pressure may plummet, and you may need oxygen. 

You’ll move to the intensive care unit (ICU). There, you’ll likely get tocilizumab (Actemra), a drug that blocks cytokines from working. That alone may solve a lot. If not, you may get steroids as well.

You may also need drugs to help your heart and blood pressure. And you may have to go on a machine to help you breathe.

This is the other main thing doctors look for. It means CAR T may affect how well your brain is working.

When it’s mild, you may have a hard time speaking or understanding what people say to you. You might also be confused or have headaches. As Jacobson puts it, “Mild would be thinking you’re in a different city or a different hospital, but being awake and alert.”

In this case, your doctor will just watch and wait. It usually doesn’t last too long and goes away on its own.

When it’s serious, it can lead to seizures or a coma. Doctors treat this with steroids.

This is another side effect that can be mild or serious. You might get a range of symptoms, from muscle twitches to confusion. Your kidneys can get overloaded as they filter out all the stuff released by dying cancer cells. 

It’s mostly a concern in the first week after treatment, but it’s not as common as you might think, Jacobson says. “We actually don’t see it that often, even though this therapy works so quickly.”

It can be treated with IV fluids and drugs used for gout. In fact, you may get one of those drugs, allopurinol (Zyloprim), ahead of time to protect your kidneys. 

With PMBL, it’s your B cells that have cancer. Normally, they make antibodies, which mark germs as something your body needs to destroy.

CAR T cells end up killing both cancerous and healthy B cells. So you could end up low on antibodies, making you more likely to get infections like colds and bronchitis. 

You get treated with immunoglobulin therapy, meaning you get shots of antibodies. How long you might need it varies. “It depends on how long it takes before their B cells come back,” Nastoupil says, adding that he's seen people need it for more than a year.

Your doctor will start to look for this side effect about a month after CAR T. If you start getting lots of infections, that’s a strong sign that your B cell count is too low.

It’s hard to say because CAR T hasn’t been around very long.

“What we don’t know about, we don’t know about,” Jacobson says.

For now, doctors know the window for serious problems early on is a short one. And that’s a good thing.  Jacobson adds, “That makes it very attractive because it’s such a limited risk.”