PET Imaging of Melanoma Using a Melanocortin 1 Receptor-Targeted Probe

The melanocortin-1 receptor (MC1R) is overexpressed in more than 80% of melanoma cells but is expressed at low levels in normal tissues, making it an important target for melanoma imaging and therapy. Recently, MC1R has attracted the interest of numerous researchers as a target for melanoma. Radiolabeled alpha-melanocyte-stimulating hormone (α-MSH) peptides bind specifically to MC1R and internalize into tumor cells, enabling melanoma diagnosis and therapy. Several radiolabeled α-MSH peptides have been developed. Among those, a cyclized α-MSH peptide produced via an alternative click chemistry cyclization strategy offers faster and more specific bindings to MC1R. It could be labeled with ²0³Pb/²¹²Pb (VMT01) for melanoma single-photon emission computed tomography (SPECT) imaging and therapy and also could be labeled with ⁶⁸Ga (VMT02) for positron emission tomography (PET) imaging. Preliminary clinical imaging showed highly sensitive and specific melanoma detection. This chapter describes the synthesis of VMT02 and PET/CT imaging procedures in both mouse models and patients.