Clinical application of 99mTc-labeled peptides for tumor imaging: Current status and future directions

Targeting receptors overexpressed on cancer cells with radiolabeled peptides has become a crucial aspect of molecular imaging in oncology. Small peptides offer favorable characteristics for tumor targeting with minimal side effects and toxicity owing to their small size and simple radiolabeling protocols. Among them, somatostatin analogs have received regulatory approval for the diagnosis and treatment of neuroendocrine tumors. Cyclic RGD (Arg-Gly-Asp) peptides, bombesin analogs, and glucagon-like peptide-1 analogs are currently under development and/or undergoing clinical trials. The most used radionuclides for tumor imaging include ^99mTc and ¹¹¹In for single-photon emission computed tomography, ⁶⁸Ga and ¹⁸F for positron emission tomography. This review highlights the clinical potential and future prospects of ^99mTc-labeled peptides for tumor imaging.