Development of Amino Acid-Based Radiopharmaceuticals for Tumor Imaging

Amino acids (AAs) are important nutrients for proliferating tumor cells, and amino acid transport is generally increased in many malignant tumor cells. So far, as a complementary category to 18F-2-fluoro-2-deoxy-D-glucose ([18F]FDG), radiolabeled amino acids that target the upregulated level of amino acid transport have been successfully employed for tumor imaging for decades, thanks to their better differentiation between tumor lesions and inflammation. This review summarizes the development of various radiolabeled amino acid analogues for tumor imaging with single photon emission computed tomography (SPECT) and positron emission tomography (PET) and introduces the basic data related to this area, such as the biological basis, chemical structure, radiolabeling, preclinical evaluation and clinical application. In addition, current status and future prospects of this class of imaging agents are discussed in this review.