AdventHealth for Children in Orlando performs its first Chimeric Antigen Receptor (CAR) T-Cell Therapy
by Amy Keller
Last February, AdventHealth for Children in Orlando performed its first CAR T-cell therapy on a young patient with recurrent acute lymphoblastic leukemia (ALL). The patient had relapsed a year after receiving a bone marrow transplant. Nine months later, he’s still in remission. Dr. Susan Kelly, a pediatric hematologist and oncologist who treated that patient, explains how CAR T-cell therapy works, who can benefit and what they can expect.
How it Works: The first step in CAR T-cell therapy requires collecting blood from the patient through a process known as apheresis. “Blood comes out of the patient, it goes into a machine and it spins the blood and it can sort the layers of the blood and it can skim off the white blood cells and return the rest of the blood to the patient,” says Kelly.
The extracted T-cells are collected in a bag, frozen and sent to Novartis, which genetically engineers them to seek out and destroy the cancer. “They use parts of a virus that can let you put DNA into a cell, and that puts an antibody on the surface of the white blood cell that turns the T-cell from a regular old T-cell into a T-cell that can fight a target on the person’s leukemia,” Kelly says.
Before the souped-up cells are infused back into the bloodstream, the patient receives “a little chemotherapy” to dampen their immune system. “Your body’s natural response to your immune system dropping is to make a bunch of proteins that make blood cells grow,” Kelly says. “It tricks the body basically into making more of those (fighter) cells we made in the lab.”
Candidates for the Therapy: While CAR T-cell therapy is not currently a first-line treatment for patients, it provides an option for children with disease that persists despite traditional chemotherapy or for those who experience too many side effects from traditional chemotherapy. It can also serve as a sort of bridge therapy to get patients into remission so they can receive a bone marrow transplant. “It’s not replacing standard therapy right now for childhood leukemia, but it is an amazing option as part of a lot of other things we can do,” says Kelly.
Side Effects: CAR T-cell therapy is easier on the organs than traditional cancer therapies, Kelly says, but it can cause acute toxicities. When the cells try to fight the leukemia, “they get very revved up” and can cause immune cytokine release syndrome, or CRS, “which basically is the immune system going over the top,” Kelly says. Some patients will experience blood pressure fluctuations or need oxygen — and because the cells can enter a person’s spinal fluid, some may become confused or sleepy. Fortunately, there are medicines that can be given to block CRS, without hindering the effectiveness of the CAR T-cells. “There are acute toxicities we see in the first week or two with patients. The more disease you have, the more likely we are to see those symptoms happen at the time the cells are given. Some can be severe and (patients) end up in the ICU, but most of those children recover fine from that. It’s just a brief period of time.”
Response Rates: Between 80% and 90% of all patients treated with CAR T-cell therapy have a sustained response, and approximately half will achieve a sustained remission of at least five years. “It’s a potential cure for some patients who didn’t respond to anything else. About half of them can be completely cured by this, and many others can go back into remission, be put on other therapies, or at least buy quality time,” says Kelly. “This is the only chance for many of these children, so even 50% is still a huge win.”