TH588 is a potent inhibitor of human 7,8-Dihydro-8-oxoguaninetriphosphatase MTH1 (NUDT1) with an IC50 value of 5 nM and good metabolic stability. MTH1 hydrolyzes oxidized purine nucleoside triphosphates that might otherwise be incorporated into DNA/RNA and contribute to DNA damage. MTH1 removal of oxidized nucleotides that result from increased levels of reactive oxygen species (ROS) in fast-proliferating cancer cells helps protect cancer cells from proliferative stress and prevent cancer cell death. TH588 is considered a new target for cancer therapy. TH588 is highly selective towards MTH1, with no relevant inhibition of other members of the nudix protein family or a panel of 87 enzymes, GPCRs, kinases, ion channels and transporter. TH588 has been shown to selectively kill a variety of cancer cell lines and with in vivo activity shown for TH588 in SW480 colorectal and MCF7 breast tumour xenografts.