How does immunotherapy for non-small cell lung cancer (NSCLC) work?

It’s important to know a little bit about the immune system to understand how immunotherapy for non-small cell lung cancer (NSCLC) works. Your immune system protects your body against germs and diseases that can make you sick. Most of the time, it knows which cells in the body are normal and healthy and which cells are not healthy. This allows it to attack disease and germ cells without attacking healthy cells.

When your immune system finds cancer cells, it goes to work to destroy them. Sometimes, it has trouble finding cancer cells because they can hide and appear like healthy cells. Cancer cells can hide from the immune system by attaching themselves to immune cells. The place on the cells where the cancer and immune cells attach to each other is called a checkpoint. These are proteins on the surface of each cell that attach the immune cell and the cancer cell together.

• The protein on the immune cell is called PD-1 or CTLA-4.
• The protein on the cancer cell is called PD-L1.

As long as the protein stays attached to the immune cell, it slows down or stops the ability of the immune cell to attack the cancer cell. Immunotherapy works to block cancer cells from attaching to immune cells, leaving the cancer cells exposed and allowing the immune system to attack them.