PARP1 and cancer: Increasing the DNA DSB burden in cancer cells via PARP1 inhibition is crucial in the treatment of tumors harboring mutant breast cancer susceptibility genes 1 and 2 (BRCA1 and BRCA2).10 They are tumor suppressors with involvement in multiple intracellular pathways, most important of which is the role of regulating the DNA damage repair defect (DDR).11