By Wendy Diller
In February of this year, the FDA approved the first radioimmunotherapy in the US, Idec Pharmaceuticals Corp. 's ibritumomab tiuxetan (Zevalin), a monoclonal antibody attached to a radioisotope indicated for treatment of certain kinds of B-cell non-Hodgkin's lymphoma. Zevalin is exciting not only because it is an effective therapy in refractory patients, but because it also demonstrates a concept that is of growing interest to diagnostic imaging experts, the ability to link a diagnostic imaging agent to a therapeutic