Furthermore, among PARP-targeting radiopharmaceuticals, [18F]olaparib [6], [18F]talazoparib [3, 4] and [18F]rucaparib [5, 7] are the 18F-labelled isotopologues of their parent compounds with identical chemical structures, which are expected to display the same pharmacokinetic and pharmacodynamic profiles in vivo, hence providing useful clinical information for PARP inhibition therapy in cancers. This evidence concerns the gene PARP1 and cancer.