Recent progress in fluorine-18 labelled peptide radiopharmaceuticals

The application of biologically active peptides labelled with positron-emit ting nuclides has emerged as a useful and interesting field in nuclear medi cine. Small synthetic receptor-binding peptides are currently the preferred agents over proteins and antibodies for diagnostic imaging of various tumo urs. Due to the smaller size of peptides, both higher target-to-background ratios and rapid blood clearance can often be achieved with radiolabelled p eptides. Hence, short-lived positron emission tomography (PET) isotopes are potential candidates for labelling peptides. Among a number of positron-em itting nuclides, fluorine-18 appears to be the best candidate for labelling bioactive peptides by virtue of its favourable physical and nuclear charac teristics. The major disadvantage of labelling peptides with F-18 is the la borious and time-consuming preparation of the F-18 labelling agents. In rec ent years, various techniques have been developed which allow efficient lab elling of peptides with F-18 without affecting their receptor-binding prope rties. Moreover, the development of a variety of prosthetic groups has faci litated the efficient and site-specific labelling of peptides with F-18. Th e F-18-labelled peptides hold enormous clinical potential owing to their ab ility to quantitatively detect and characterise a wide variety of human dis eases when using PET. Recently, a number of F-18-labelled bioactive peptide s have shown great promise as diagnostic imaging agents. This review presen ts the recent developments in F-18-labelled biologically active peptides us ed in PET.