Breakthrough in Treating Cancers
Prof CHE Chi Ming, Mr ZOU Taotao
Department of Chemistry
US Patent No. 8,828,984 granted on September 9, 2014
Cisplatin is the first platinum-containing anti-cancer drug and it is used to treat various types of cancers. Its platinum complexes cause crosslinking of DNA and trigger apoptosis (programmed cell death), but they also lead to severe side effects and resistance problems, which has hindered wide application of the drug. Given that cancer is a leading cause of death worldwide, causing seven million deaths every year, there is an urgent need to develop newer chemo agents that have fewer side effects but comparable efficacy to Cisplatin.
New classes of anticancer drugs, such as gold(I)/gold(III) compounds targeting different cellular components, have been developed to tackle cisplatin-related resistance by inducing DNA-independent apoptosis. However, gold(III) compounds are unstable towards glutathione (GSH) in nature while gold(I) compounds quickly undergo a ligand exchanging reaction with physiological thiol, which contribute to bioavailability issues as seen in most other cancer drugs.
Now, with this invention, there is a new class of gold(III) compounds, Au(III)-NHC complexes, which can inhibit cell proliferation and tumor growth in mice models. These complexes have fewer side-effect than Cisplatin but are just as effective. The release of the ligand upon Au(III) to Au(I) reduction also switches on the fluorescence NHC complex, thus serving as thiol probes to detect the tumor location.