Since 2009, when a first-in-human clinical trial of Olaparib confirmed the synthetic lethal interaction between inhibition of PARP and BRCA deficiency [51], PARPi therapies have been approved for the use in several cancers, including BC, OC, pancreatic and prostate cancer [52,53,54], as summarized in Table 2. The gene discussed is PARP1; the disease is prostate cancer.