Exposing a skin cancer drug enzymically

British scientists have developed a new class of pro-drug for treating skin cancer that might avoid the side effects of conventional treatments. Helen Osborn of Reading University says that the pro-drugs have lower overall toxicity because the cytotoxic drug itself is released only in the vicinity of malignant melanoma cells. The key to the new approach lies in exploiting the presence of high levels of the enzyme tyrosinase in melanoma cells. The enzyme is almost absent from other cells. The pro-drug is comprised the cytotoxic agent and a side-group that deactivates it. The enzyme removes the side-group exposing the cancer cell to the drug.