TOPARP-A (The Trial of PARP Inhibition in Prostate Cancer) phase 2 trial studied the PARP inhibitor olaparib in mCRPC patients showing good response rates particularly for BRCA1/2 or ATM gene-mutated tumours that justified the breakthrough therapy designation by FDA (Food and Drug Administration) [23]. This evidence concerns the gene PARP1 and Familial prostate cancer.