M4344 + niraparib

M4344 + niraparib is an investigational combination therapy consisting of two small molecule inhibitors targeting DNA damage response pathways in cancer cells. - **M4344** is a potent and selective inhibitor of ataxia telangiectasia and Rad3-related protein (ATR), a key regulator of the cellular response to DNA replication stress and damage. By inhibiting ATR, M4344 disrupts the ability of cancer cells to repair DNA damage, leading to cell death—especially in tumors with high replication stress or defects in other DNA repair mechanisms[2]. - **Niraparib** is an oral poly(ADP-ribose) polymerase (PARP) inhibitor that blocks PARP1/2 enzymes involved in single-strand DNA break repair. Inhibition leads to accumulation of unrepaired DNA breaks, resulting in synthetic lethality particularly in tumor cells with homologous recombination deficiency (HRD)[6][8][10]. The combination aims for synergistic antitumor activity by simultaneously blocking two critical nodes of the DNA damage response pathway—ATR and PARP—thereby overwhelming cancer cell repair capacity and promoting apoptosis. This approach is being evaluated primarily for advanced solid tumors with defective DNA repair mechanisms[3][1].