Targeted radionuclide therapy: current status and potentials for future improvements

target cell while the absorption of the radioactivity in non-target tissue should be as low as achievable. Usually, this goal is reached by coupling the radionuclide to a vector which recognises a structure, e.g. receptor, on the target cell. By far the most established combination is the somatostatin receptor (sst) and radiolabeled somatostatin analogues. The majority of neuroendocrine tumours feature a strong over-expression of the somatostatin receptors (sst), mainly subtype 2 (sst2). Somatostatin receptors are attractive targets for radiolabelled peptides since the density of sst on tumours is vastly higher than on non tumour tissue. In addition to the favourable receptor distribution, sst2 internalises into the cell after a ligand bound to the receptor. Consequently, radioactivity delivered by the vector is captured in the target cell after binding