Imexon

Imexon enters the cell and binds to glutathione and other sulfhydryl compounds, effectively preventing them from scavenging the toxic free radicals. So, particularly in the rapidly dividing cancer cell, free radical build-up in the presence of imexon leads to changes in mitochondrial membrane potential and ultimately to the mitochondria swelling and bursting. Mitochondrial proteins, in particular cytochrome c, are released into the cytoplasm and this activates caspase-mediated apoptosis resulting in cancer cell death. This sequence of events has been well characterized and published in several papers in leading cancer journals. Imexon is probably the only cancer drug under development at this time which exploits this mechanism of action. Imexon is an inhibitor of ribonucleotide reductase, a key enzyme in DNA synthesis that is also a target for gemcitabine. Imexon is also a cell cycle inhibitor and in the presence of the drug cells accumulate in S phase.