By 1997, Kufe had created a vaccine that effectively treated tumors in mice. Other cancer vaccines now under development rely on stimulating the body's immune system to attack a specific protein made by tumor cells. However, such targets are difficult to identify. Also, Kufe notes, the target may move, that is, the protein may figure out a way to change, as do proteins on the flu virus. Kufe's team, including postdoctoral researcher Jianlin Gong, avoided these problems by combining cells from kidney tumors with immune cells from a patient's blood.
Tumor cells contain all the possible target proteins.
The immune cells arouse the body's defenses to find and attack every one of them, whether their identities are known or unknown. In contrast to vaccines against flu or polio, which prevent these diseases, the hybrid vaccine causes the body to reject tumor cells already present. When the German researchers read Kufe's reports, they decided to try the vaccine in humans. That's easier to do in Germany than in the United States, where the Food and Drug Administration requires extensive tests to demonstrate the safety of a new vaccine, a process that takes years. One big worry involved the possibility that the hybrid vaccine might induce the defense system to attack normal cells, causing the body to reject parts of itself.