The invention relates to a new lutetium-177 therapeutic radiopharmaceutical as an inhibitor of prostate-specific membrane antigen (iPSMA), wherein 1,4,7,10-tetraazacyclododecane-N,N´,N´´,N´´´´-tetraacetic acid (DOTA) bonded to the heterocyclic molecule hydrazinonicotinamide (HYNIC), generates a rigid chemical structure that minimises the number of conformers and intramolecular hydrogen bonds, thereby producing a favourable spatial orientation of the active site (Lys(Nal)-NH-CO-NH-Glu) in the molecule, for biological recognition by the PSMA protein. The new 177Lu-DOTA-HYNIC-iPSMA radiopharmaceutical accumulates, with high affinity in vivo, in tumours that overexpress the PSMA protein, acting as a radiotherapeutic agent. The purpose of the invention is to provide a new specific radiopharmaceutical (molecular target radiopharmaceutical) for the treatment of tumours with PSMA overexpression.
