VX-984 (M9831) is an orally active, potent, selective, and ATP-competitive inhibitor of DNA-PK. VX-984 effectively suppresses non-homologous end joining (NHEJ) and increases DNA double-strand breaks (DSBs). It enhances the cytotoxic effects of ionizing radiation (IR) in various cancer cell lines, including non-small cell lung cancer (NSCLC) cell lines, in vitro. Additionally, VX-984 reduces DNA-PKcs autophosphorylation.