How can we induce the body to use its own weapon, the immune system, to battle cancer? In principle, by the same means used against infectious diseases: immunization. The production of a selective vaccine is not a trivial task, however. A team led by Horst Kunst at the University of Mainz has now found a way to bind a molecule that is typical for tumors to a carrier protein without irritating the immune system. As they report in the journal Angewandte Chemie, their method is based on an immunocompatible connection by way of a sulfur atom, namely, a thioether.