By Susan Gaidos
It looked like a lost cause: a 61-year-old patient with advanced pancreatic cancer — one of the deadliest diagnoses. Ordinarily, doctors wouldn’t have much choice. They could try chemotherapy drugs one at a time to see if any worked, or they could slam the tumor with a cocktail of chemicals that had shown some success with similar cases.
But this time the doctors had another option: trying out potential treatments on mice. These weren’t run-of-the-mill lab rodents, though. Scientists had created 17 mice with an immune system matched to the patient’s. After growing “copies” of the patient’s cancer in the mice, doctors tried a slew of different treatments on the tumors and discovered that the cancer was extremely sensitive to one particular drug.
Scientists had implanted human tumors in mice before. But there was no guarantee that mice would respond to drugs the way a person would. In the new approach, young mice engineered to lack immune systems receive transplants of portions of a patient’s immune system. As the mice mature, they develop a humanlike immune response to drugs or infectious agents.