111In-DOTA-GlyGlu-CycMSH

111In-DOTA-GlyGlu-CycMSH is a radiolabeled peptide-based imaging probe designed for the detection of melanoma. It consists of a cyclized alpha-melanocyte-stimulating hormone (α-MSH) analogue modified with DOTA (a chelator for radiometals), with an N-terminal Glycine-Glutamic acid (GlyGlu) linker, and is labeled with the diagnostic radionuclide indium-111 (111In). The compound specifically targets the melanocortin 1 receptor (MC1R) expressed on melanoma cells via receptor-mediated internalization. In preclinical models, it produced high tumor uptake, rapid clearance from normal tissues (except kidneys), and favorable tumor-to-background ratios, allowing for high-contrast SPECT imaging of primary and metastatic melanoma lesions[1][2][4].