PARP1 and cancer: These DNA strand breaks are normally repaired by the homologous recombination repair (HRR) pathway, for which key components include the tumour suppressor proteins BRCA1 and BRCA2.6 Therefore, PARP inhibition has potential as targeted therapy for cancers with underlying defects in HRR, such as BRCA-mutated tumours and platinum-sensitive ovarian cancers.6,7 PARP inhibition may also serve as a sensitiser, potentiating the activity of a variety of DNA-damaging agents, including topoisomerase inhibitors, alkylators, and platinum-based agents.8–10