How the Immune System Fights Cancer
The battle begins as soon as healthy cells mutate into cancer cells.
Researchers discover how cancer masks itself from the immune system and figure out how patients’ immune systems can recognize cancer cells and attack them.
How the Immune System Fights Cancer
Published: April 9, 2020
Narrator: For years, scientists believed the immune system could not attack cancer cells, because, unlike an invading virus or bacteria, they are considered to be part of us.
Kevin Lee: Cancers are really 99 percent you. They’re 99 percent normal, so the immune system largely sees them as normal.
Narrator: Even into the 1980s, researchers who believe they can harness the immune system against cancer are considered renegades.
Olivera Finn: I was a graduate student in the late ’70s, at Stanford. People were suspicious of the ability to actually provoke an immune response against the cancer cells. We’re saying we can do something against cancer, and everybody’s sort of laughing, right?
Narrator: But it turns out the immune system does fight cancer. The battle begins as soon as normal cells mutate into cancer cells.
Lee: Long before anybody knows that they have cancer, there’s this ongoing war of the immune system trying to control the cancer and the cancer trying to escape.
Narrator: If the cancer learns how to mask itself from the immune system, it can gain the upper hand and grow.
Lee: So, by the time the cancer actually grows large enough to be detected by our normal tests, it’s already figured out how to get away from the immune system.
Narrator: But finally, researchers learned how cancer masks itself.
Kunle Ounsi: When you and I get an infection, usually the immune system revs up, but at some point, the immune system has to stop and rest.
Narrator: The body has natural mechanisms that stop the immune system so it won’t damage ordinary cells. These are called checkpoints.
Ounsi: But it turns out that these same mechanisms that tell the immune system to stop, have been hijacked in cancer. The cancer is sending a signal to the immune system to stop.
Onscreen: Researchers figured out how to turn the immune system back on.
Narrator: Their discoveries led to checkpoint inhibitors, drugs that can turn cancer’s signal off. Now the immune system can recognize the cancer and attack.
Elizabeth Jaffee: It took 30 years of understanding the immune system, before we could understand how to make the immune system recognize cancer.
PRODUCTION CREDITS
Cuba's Cancer Hope
Edited by: Robert Kirwan
Produced by: Kelly Thomson
Directed by: Llewellyn M. Smith
Digital Producer: Angelica Coleman
© WGBH Educational Foundation
- Angelica Coleman
