Current and potential therapeutic uses of lanthanide radioisotopes

In the last 25 years, diagnostic nuclear medicine has come to depend an the versatile chemistry of a single radioisotope, technetium-99m (Tc-99m), Dif ferent chelating molecules can be used to guide Tc-99m through various phys iological path ways in the body to gain information about disease scares. N o single radioisotope similarly dominates therapeutic applications. In the field of radioisotope therapy, much discussion and debate have focused on w hat radioisotope might be "ideal" for treatment of malignant tumors. The id eal may not be a single radioisotope, but rather the class of very closely related radiolanthanides and lanthanide-like radioisotopes. These radioisot opes possess strikingly similar chemistries and thus all may be conjugated to biomolecules using a single chelate, the DOTA moiety land ifs chemical a nalogs). They also provide a wide range of physical characteristics, such a s half-lives and beta energies, that can be chosen to march the biological properties of the conjugated biomolecule and the malignant tumor. Thus, the radiolanthanide-DOTA bioconjugate model provides a set of physically diver se, but chemically very similar, therapeutic radiopharmaceutical agents, th e individual members of which can be tailored to treat specific types of ca ncers.