Describes a condition in which T cells (a type of immune cell) lose their ability to kill certain cells, such as cancer cells or cells infected with a virus. This can happen when cancer, chronic infection, or other conditions cause the body’s immune system to stay active for a long time. Exhausted T cells have high amounts of immune checkpoint proteins on their surface, which may keep the activity of the T cells suppressed. In cancer treatment, drugs that target these proteins may be given to allow the T cells to better kill cancer cells. Learning more about T-cell exhaustion may help in the development of new types of immunotherapy to treat cancer.

Okay, so I'm a hypochondriac already. Are you telling me I have cancer now???!!!