CAR T-Cell Therapy: How It Works in Cancer

CAR T-cell therapy turns your own immune cells into a living cancer treatment. Doctors remove some of your T cells, a type of white blood cell. In a lab, they add a gene that makes the cells recognize your specific cancer. Then they grow millions of these engineered cells and infuse them back into you.

First, a machine collects your T cells from your blood in a process called leukapheresis. This takes a few hours and does not require surgery. The cells are then shipped to a lab, where scientists insert a gene for a chimeric antigen receptor, or CAR. This receptor lets the T cells recognize a specific marker on your cancer cells. The lab grows the modified cells until there are hundreds of millions of them. Before the cells are given back, you usually get a short course of chemotherapy, called lymphodepletion, to make room for the new cells to expand. The whole process, from collection to infusion, usually takes three to five weeks.

CAR T-cell therapy is FDA-approved for several blood cancers. This includes B-cell acute lymphoblastic leukemia in children and young adults, and several options for adults with multiple myeloma, lymphoma, and chronic lymphocytic leukemia. It is generally used after other treatments have not worked, though this is starting to change for some cancers.

Most people who get CAR T-cell therapy develop some degree of cytokine release syndrome, usually within the first one to two weeks. This happens as the new T cells activate and multiply. Symptoms range from a mild fever to a dangerously high fever and a serious drop in blood pressure. In rare cases, it can be fatal without treatment. Doctors manage it with a drug called tocilizumab, which blocks a signal called IL-6, and sometimes steroids.

CAR T-cell therapy can also cause neurologic side effects, sometimes called ICANS. Symptoms include confusion, trouble finding words, and extreme sleepiness. These can worsen quickly, so report any new confusion right away rather than waiting. Treatment includes steroids, and a drug called anakinra when steroids are not enough.

Because of these risks, CAR T-cell therapy is given only at specialized centers, and you will likely need to stay nearby for two to four weeks after infusion, even if you are not admitted the whole time. This allows the team to catch and treat reactions quickly.

• Is CAR T-cell therapy an option for my specific cancer and situation?
• How long is the full process, from cell collection to infusion?
• What are the warning signs of cytokine release syndrome or neurologic side effects?
• How long will I need to stay near the treatment center?
• What happens if I don't respond, or if the cancer returns afterward?

Your center will give you a card and a 24-hour number before you go home. Carry both, and let whoever is staying with you read this section, since you may not be the one who notices.

• Call 911 or go to an emergency department if you cannot be roused, you have a seizure, you stop making sense or cannot get words out, or you feel faint with a racing pulse and cold clammy skin. Say "I have had CAR T-cell therapy" as the first sentence, and give the date of the infusion.
• Call the 24-hour cell therapy line at once, and go to an emergency department if you cannot reach them, when your temperature reaches 100.4°F (38°C) or higher, you have shaking chills, or your blood pressure readings are running low. CDC treats a fever this high after chemotherapy as an emergency, and fever is also the usual first sign of cytokine release syndrome, which is treated with tocilizumab. This is not a wait-until-morning call.
• Get emergency help the same hour if anyone notices you are muddled, unusually sleepy, writing or speaking oddly, or losing track of the day. NCI names confusion, excessive sleepiness and impaired speech as the hallmarks of the neurologic reaction, and it can deepen within hours. Do not wait to see whether it clears.
• Call the team within a day or two if you are newly short of breath on stairs, bruising easily, or picking up one infection after another. Counts can stay low for weeks after infusion.

For the first few weeks after infusion you should not be alone overnight, and you should not drive.

• National Cancer Institute — CAR T Cells: Engineering Immune Cells to Treat Cancer.
• National Cancer Institute — T-cell Transfer Therapy.
• CDC — Fever and Cancer Treatment.