Evaluation of a Novel Pb-203-Labeled Lactam-Cyclized Alpha-Melanocyte-Stimulating Hormone Peptide for Melanoma Targeting.

The purpose of this study is to examine the melanocortin-1 receptor (MC1R) targeting and specificity of ²⁰³ Pb-DOTA-GGNle-CycMSH _hex in melanoma cells and tumors to facilitate its potential therapeutic application when labeled with ²¹² Pb. The MC1R-specific targeting and imaging properties of ²⁰³ Pb-DOTA-GGNle-CycMSH _hex were determined on B16/F1 and B16/F10 murine melanoma cells and in B16/F1 flank melanoma-, B16/F10 flank melanoma-, and B16/F10 pulmonary metastatic melanoma-bearing C57 mice. ²⁰³ Pb-DOTA-GGNle-CycMSH _hex displayed MC1R-specific binding on B16/F1 and B16/F10 melanoma cells and tumors. B16/F1 flank melanoma, B16/F10 flank melanoma, and B16/F10 pulmonary metastatic melanoma lesions could be clearly imaged by single photon emission computed tomography (SPECT) using ²⁰³ Pb-DOTA-GGNle-CycMSH _hex as an imaging probe. The favorable melanoma targeting and imaging properties highlighted the potential of ²⁰³ Pb-DOTA-GGNle-CycMSH _hex as a MC1R-targeting melanoma imaging probe and warranted the evaluation of ²¹² Pb-DOTA-GGNle-CycMSH _hex for melanoma therapy in future studies.