Radiolabeled peptides in diagnosis and therapy

During the past few years, there has been exponential growth in the develop ment of radiolabeled peptides for diagnosis and therapy. This is because th e peptides can be synthesized easily and inexpensively, they have fast clea rance and rapid tissue penetration, and they are less likely to be immunoge nic. More importantly, most peptides have a high affinity for characteristi c receptor molecules that are overexpressed on malignant mammalian cells. P eptides can be labeled with a variety of radionuclides intended for specifi c applications, diagnostic or therapeutic, by using both conventional and n ovel chelating moieties, many of which can be incorporated during the solid state synthesis of a chosen peptide. High specific-activity peptides can b e prepared and used to minimize unwanted physiologic effects, and known seq uences of amino acids can be modified to slow their in vivo catabolic rate. These characteristics have paved the way for the preparation of a large nu mber of radiolabeled peptides for a variety of clinical and experimental ap plications. This article briefly discusses the peptide chemistry; it also s ummarizes the preparation of radiolabeled peptides and outlines their appli cations in imaging vascular thrombosis, detecting infection and inflammatio n, and localizing tumors. Their therapeutic applications in oncology are al so presented and the future directions outlined. Peptides that have been ap proved for human use, such as AcuTect (Diatide, Londonderry, NH) or OctreoS can (Mallinckrodt, St. Louis, MO), or those that have made it to clinical t rials, are emphasized. Also discussed are selected promising agents that ar e still in preclinical investigation. Copyright 2001 by W.B. Saunders Compa ny.