PARP inhibitors (PARPi) such as Olaparibare now under clinicalinvestigation in both single-agent and combination treatment regimens,1 and they achieve their effects by preventingthe repair of DNA single-strand breaks (SSBs) or stalled replicationforks, generating cytotoxic DNA double-strand breaks (DSBs) that triggercell death by apoptosis.2 Through syntheticlethality, cancers with deficient BRCA pathways are hypersensitiveto PARP inhibition3 and, as a consequence,PARP inhibitors have been employed as treatments for BRCA-deficientbreast cancers to great effect. Here, PARP1 is linked to cancer.