The human immune system is powerful and complex.
It can identify and destroy invaders of nearly infinite variety, yet spare the more than 30 trillion cells of the healthy body.
Unfortunately, the broken cells of cancer are able to retain, and boost, the “recognize and ignore me” signals of undamaged cells, letting them evade detection by the immune system. As a result, these damaged cells grow unmolested, destroying the normal physiological functioning of tissues and organs.
Armed with new insights into the interactions between cancer and the immune system, research teams are developing novel treatments to harness the full potential of the body’s natural defenses. This is called immunotherapy.
In animal models and clinical trials, breakthrough immunotherapies are emerging, techniques that train the immune system to recognize and attack cancer as the enemy.
One way is through drugs that help the immune system find and destroy cancer cells. Another way is through vaccines that can teach the body to recognize cancer cells.
Recently, studies have paired immunotherapies with modified viruses that attack tumor cells and keep them from returning.
With promising results, such new weapons are providing hope that cancer can ultimately be defeated.
Harnessing the immune system
When foreign cells – like viruses or bacteria – infect the body, the immune system springs into action. It produces antibodies that bind to proteins called antigens on the surface of the foreign cell. Sometimes this is enough to neutralize the foreign cell. In other cases the antibodies bind to the antigen and mark the cell for destruction by T-cells, or both.
Cancer cells also produce antigens. But even though cancer cells are not normal and would otherwise be marked for destruction, antibodies don’t bind to their antigens and the immune system does not destroy them. This is because cancer cells have evolved to hijack normal protective checkpoints in the immune system to protect themselves from elimination.
Cancer cells ramp up those barricades to stay shielded and simultaneously weaken immune cells. This allows them to grow unchecked, developing blood vessels and invading into other tissues.