New chemotherapy more selective.

• Position: Cancer Cells

One of the largest challenges of chemotherapy lies in the fact that cancer cells need to be killed while healthy tissue must be protected. French researchers have introduced a new approach in Angewandte Chemie: the enzyme B-galactosidase releases the active drug from an inactive precursor, known as a prodrug, which only can be taken up by tumor cells.

A number of tumor-specific markers have been found over the years. These are receptors that are commonly located in the cell membranes of tumor cells, but are absent from, or rare, on the surfaces of healthy cells. Previously, researchers mostly have used antibodies directed toward these receptors to deliver drugs selectively to tumor cells. The disadvantages of this method not only are the high cost and difficult development and production, but the inherent risk of undesired immune responses.

A team led by Sebastien Papot at the University of Poitiers, France, has developed a simpler approach that works without antibodies. It is based on a prodrug with four components: the actual cytotoxic agent, a ligand that recognizes one of the tumor-specific receptors, a "trigger" for the release, and a linker that holds everything together.

In the first step, the ligand binds to the tumor-specific receptor...