Definition

A radioconjugate composed of the melanocyte-stimulating hormone receptor (MSHR; melanocortin-1 receptor; MC1R; melanin-activating peptide receptor; melanotropin receptor)-targeting peptide, VMT01, labeled with the radioisotope lead Pb 203, with potential imaging activity using single photon emission computed tomography (SPECT)/computed tomography (CT). Upon administration of lead Pb 203-VMT01, VMT01 targets and binds to MC1R-expressing tumor cells. Upon SPECT/CT imaging, MC1R-expressing tumor cells can be detected. MC1R, a G protein-coupled receptor expressed by melanocytes that binds to melanocortins, is involved in regulating mammalian skin and hair color. It is upregulated on the surface of metastatic melanoma cells.