Lead-203-Labeled Alpha-Melanocyte Stimulating Hormone Peptide as an Imaging Probe for Melanoma Detection

Peptide-targeted alpha therapy with 7.4 MBq of 212 Pb-[1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid-ReO-[Cys 3,4,10 , d -Phe 7 , Arg 11 ]α-MSH 3-13 { 212 Pb-DOTA-Re(Arg 11 )CCMSH} cured 45% of B16/F1 murine melanoma-bearing C57 mice in a 120-day study, highlighting its melanoma treatment potential. However, there is a need to develop an imaging surrogate for patient-specific dosimetry and to monitor the tumor response to 212 Pb-DOTA-Re(Arg 11 )CCMSH therapy. The purpose of this study was to evaluate the potential of 203 Pb-DOTA-Re(Arg 11 )CCMSH as a matched-pair SPECT imaging agent for 212 Pb-DOTA-Re(Arg 11 )CCMSH.