Immunotherapy offers the promise of stimulating the body’s immune system to destroy tumor cells, but it only works for a handful of cancers. MIT researchers have now discovered a novel technique that they hope could enable it to target more types.

The surprising key to the approach is using chemotherapy to injure cancer cells without killing them. Led by professors Michael Yaffe and Darrell Irvine, the researchers remove tumor cells from the body, treat them with existing drugs, and then place them back in the tumor. When delivered along with drugs that activate the immune system’s T cells, these injured cancer cells appear to act as a distress signal that spurs the T cells into action against the tumors. Chemotherapy drugs that cause DNA damage are especially well suited for this type of treatment.

In 40% of mice with melanoma and breast tumors, the treatment completely eliminated the tumors. And when the researchers injected cancer cells into these same mice several months later, their T cells recognized them and destroyed them before they could form new tumors.

“When you create cells that have DNA damage but are not killed, under certain conditions those live, injured cells can send a signal that awakens the immune system,” says Yaffe. He hopes to test the approach in patients whose cancers have not responded to other immunotherapy.