How immunotherapy helps the body fight cancer cells

To better understand immunotherapy, the popular new field of cancer research, try thinking about it like a car, says Johns Hopkins University oncologist Drew Pardoll.

Pardoll spoke as part of Chasing Cancer, a conference of cancer experts presented by The Washington Post earlier this month.

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"To get from Point A to B with a car, you need three things: You need the gas pedal to go, but you also need the brakes, and it also helps to have a steering wheel," Pardoll said. "The immune system can steer itself very carefully and in a very focused way. In fact, it's the genetic signatures in a cancer cell that the immune system can use to distinguish a cancer cell from a normal cell. . . . What we learned on the platform of basic immunology is that the problem was the parking brake was thrown on so you push on the gas and the car still doesn't go."

Immunotherapy aims to release the "parking brake" and allow a patient's own immune system combat the cancer cells, said Pardoll. In about 20 percent of cancers, he said, the immune system is poised to take on cancer cells like a car facing downhill: "All you have to do is disable one parking brake and the immune system goes after that tumor."

Johns Hopkins is among the nation's leading institutions to expand the field of immunotherapy. Earlier this year, Johns Hopkins launched the Bloomberg–Kimmel Institute for Cancer Immunotherapy and named Pardoll the institute's inaugural director.

"We think of precision immunotherapy as figuring out, for each of the patients, which of the parking brakes and which of the accelerators to combine," said Pardoll at Chasing Cancer.

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