PARP1 and cancer: The dual-insult of HR and BER defects results in “synthetic lethality” justifying the potent and lethal synergy between these two otherwise non-lethal event when they occur alone [1, 11]. Therefore, this review aims to address the role of common PARP inhibitors on cancer chemotherapy with special focus on niraparib and its first global approval for maintenance therapy of gynecologic cancers.