TH5427hydrochloride is a potent and selective inhibitor of NUDT5 with an IC50 of 29 nM. It demonstrates a remarkable 690-fold selectivity towards NUDT5 compared to MTH1. Moreover, TH5427hydrochloride effectively inhibits progestin-dependent, PAR-derived nuclear ATP synthesis in breast cancer cells, thereby impeding chromatin remodeling, gene regulation, and ultimately suppressing proliferation.