There are currently four FDA-approved PARP-Is for cancer therapies, talazoparib (Talzenna, Pfizer), olaparib (Lynparza, AstraZeneca), rucaparib (Rubraca, Clovis Oncology) and niraparib (Zejula, GlaxoSmithKline), with many more in various phases of development looking to expand their application in cancer therapy and beyond (33–35). This evidence concerns the gene PARP1 and cancer.