CAR T-Cell Therapy as a Treatment for Cancer
By William Huang
Cancer is one of the most prominent diseases in the world, being the 2nd highest leading cause of death in the United States as ranked by the CDC. One factor for this unfortunate statistic is that it is also one of the hardest diseases to treat due to its nature. Cancer is caused by a human’s own cells, making anti-pathogenic treatments ineffective. Normally, our cells grow and divide when new cells are needed, and dead cells are replaced with new cells. However, with cancer, damaged and old cells survive when they are meant to die, and new cells are formed when they are not necessary. These excess new cells can divide indefinitely and cause the formation of growths called tumors.
The immune system recognizes foreign substances in the body by finding proteins called antigens on the surface of cells. T cells have proteins called receptors that attach to foreign antigens and trigger other parts of the immune system to destroy the foreign substance. This relationship is very personalized. Each foreign antigen has a unique immune receptor that can bind to it. Cancer cells also have antigens, but if your immune cells don't have the right receptors, they can't attach to the antigens and help destroy the cancer cells.
One common treatment to prevent these fast-growing cells is chemotherapy, but this has severe side effects for a patient and can cause them to feel very weak. One innovative solution is a treatment called CAR T-Cell Immunotherapy. Immunotherapy is a combination of the terms immuno and therapy. Immuno refers to the immune system, and therapy is a treatment. So immunotherapy is a treatment that is meant to boost a patient’s immune system, in this case to fight cancer. CAR is an acronym that stands for “Chimeric Antigen Receptor.” Do you know what Chimeric means? Chimeric refers to a creature from Greek mythology called a “Chimera,” which is a hybrid animal mixed with a lion, a goat, and a snake. Why is the receptor described as chimeric? It’s because the receptor is a “hybrid” between antigen-binding and T-cell activating functions. Receptor refers to the structure that is engineered onto the surface of T-cells. Lastly, T-cells are a type of white blood cell that works within the immune system. There are two major subtypes of T-cells: killer and helper. Killer cells are able to directly target and kill virus-infected cells, while helper cells help in the maturation of other cells within the immune system. In short, CAR T-Cell Immunotherapy is just a treatment that engineers immune cells to have a hybrid response to cancer cells
Because T-cells are not invasive organisms, they cannot reduce cancer cells, and are not flagged by antibodies. This is a huge obstacle because the immune system is the most powerful tool that can be used to destroy cancer cells. To avoid this, researchers developed a technique in which specific receptors can be added to the surfaces of T-Cells in order to destroy cancer cells through the immune system. The Chimeric Antigen Receptor, or CAR, is added to T-Cells, and functions like an antibody that flags cancer cells, which then allows T-Cells to identify and destroy them.
Citations:
https://www.cancer.gov/about-cancer/treatment/research/car-t-cells
https://www.uchicagomedicine.org/forefront/cancer-articles/a-walking-miracle-car-t-cell-therapy
Image Credit:
https://www.elicera.com/technology
