tuvusertib + niraparib

**tuvusertib + niraparib** is an investigational combination of two orally administered small molecule inhibitors targeting distinct elements of the DNA damage response pathway. **Tuvusertib** is a selective inhibitor of ataxia telangiectasia and Rad3-related (ATR) protein kinase, while **niraparib** is a selective inhibitor of poly(ADP-ribose) polymerase (PARP) enzymes PARP-1 and PARP-2. The combination aims to exploit synthetic lethality by jointly blocking ATR- and PARP-mediated DNA repair, thereby enhancing DNA damage, replication stress, and apoptosis in cancer cells—particularly those with homologous recombination deficiency (HRD), such as BRCA1/2 mutant or PARP inhibitor-resistant ovarian cancer. This combination has demonstrated promising clinical activity and manageable safety in early-phase trials in various advanced solid tumors, including PARPi-resistant malignancies.