PARP1 and cancer: These cancer cells are dependent on poly(ADP)-ribose polymerase 1 (PARP1) for single-strand DNA repair; thus, PARP inhibitors (PARPi) were developed specifically to treat BRCA-/- cancers by trapping PARP1 at single-strand breaks in DNA, causing replication fork collapse and cytotoxicity to the rapidly proliferating cancer cells [3].