Your immune system is really powerful. It is constantly surveying your body, looking for intruders. When the immune system sees something that looks different, it says, “You don’t belong here.” It then attacks the interloper and clears it from the body. This is what happens with infections all of the time.
When you get cancer, your immune system, for whatever reason, wasn’t able to recognize the cancer cell as different and therefore could not kill it. CAR T-cell therapy seeks to help the immune system find tumor cells more efficiently, while still using the immune system’s power to destroy the abnormal cells.
CAR stands for chimeric antigen receptor. This receptor is designed to target a specific molecule that is present on the surface of a cancer cell.
In CAR T-cell therapy, doctors first remove T cells from a person’s blood. The immune cells are then engineered in a lab so that each T cell has a CAR on its surface, making it into a CAR T cell. Once the transformed CAR T cells are infused into the patient, the cells roam around the body looking for their specific target. (In our SJCAR19 clinical trial, that target is the CD19 molecule.) When they find the intended target, the engineered immune cells bind to the cancer cell and kill it.
If you think about how chemotherapy, radiation and other non-immune therapies work, they’re nonspecific. It’s like throwing a big bucket of water at everything as opposed to going for the source of the fire. It’s amazing that you can use the body’s own immune system and make it work better to fight cancer.
CAR T-cell therapy is quite powerful. For patients with acute lymphoblastic leukemia (ALL) in particular, CAR T-cell therapy is able to get the vast majority of patients into remission, sometimes for the first time since they began treatment. The length of remission varies between patients, and we do not know enough yet to determine up front for whom CAR-T therapy can be their final therapy. But, getting someone into even a temporary remission may provide a patient with the best chance to receive other therapies, such as hematopoietic cell transplant, which we know has a high chance at providing a long-term cure.
There are certain patient populations whose type of cancer simply does not respond well to chemotherapy. As we learn more and more about CAR T-cell therapy, it might be a frontline option for these patients. But we’re not there yet. As a field, that’s definitely something we are pursuing.
The St. Jude clinical trial SJCAR19 is designed for children, adolescents and young adults with ALL whose cancer has never responded to treatment, or has returned after treatment. This study targets the CD19 molecule on leukemia cells.
SJCAR19 features modified T cells that are similar to an FDA-approved product already on the market. The way the CAR finds CD19 is the same and the way it stimulates the T cells is the same, but we’ve made some changes to the vector backbone that will hopefully make it safer in the long run. Also, changes we’ve made to the manufacturing process may make it a better product that can last longer in the body or be more effective in killing cancer cells. These are things we will evaluate as part of the clinical trial.
St. Jude is a wonderful place where we provide state-of-the-art care for patients. We have a lot of resources available and a strong multidisciplinary team. There are many people involved in the care of every single patient, and we do everything we can to provide the best care to each child who comes through our doors.
SJCAR19 is the first of many CAR-T trials we’re planning. Eventually, we hope to use CAR T-cell therapy to treat acute myeloid leukemia, as well as some solid tumors and brain tumors. For me, this is not a job. It’s my ideal calling: to be part of a family’s journey, and also to be part of incredible science that’s growing and changing.