In one recent study, Australian researchers were working with a pancreatic cancer patient, trying to determine genetic mutations that could make his cancer susceptible to certain drugs, reports Nature News. They grafted a piece of the patient's tumor tissue onto mice with depleted immune systems, so the mice would not reject the transplant. They tested a cancer drug that their gene screening suggested could work, and they were right — the tumor shrank after the mice were treated. Sadly for the patient, he died before he could be treated, too. The researchers presented their work at a conference last week.