Immune checkpoint inhibitors

Immune checkpoint inhibitors are a cancer treatment that works through the body's own defenses. These drugs are monoclonal antibodies, proteins built to latch onto a very specific target, and their job is to unlock the immune system so it can recognize tumors and destroy them.

To understand how they work, you first need to meet T cells, a type of white blood cell that protects the body. The immune system has its own brakes, called checkpoints, which keep a defensive response from getting so strong that it ends up destroying healthy cells. Picture an off button on the surface of the T cell: that button is a protein called PD-1. The tumor cell carries another protein, called PD-L1, that fits right onto that button. When they come together, the T cell gets an “off” signal.

That's where the drug comes in. It gets in between those proteins and keeps them from fitting together, so the button never gets pressed. The off signal never arrives, and the T cell can kill the cancer cell. Side effects aren't the same for everyone; they vary from person to person, and the rarer ones can include widespread inflammation, meaning irritation and swelling in different parts of the body.