Linker modification reduced the renal uptake of technetium-99m-labeled Arg-Ala-Asp-conjugated alpha-melanocyte stimulating hormone peptide

The purpose of this study was to examine the biodistribution of 99mTc-RAD-Arg-(Arg11)CCMSH in B16/F1 melanoma-bearing C57 mice to determine whether the replacement of the Lys linker with an Arg linker could decrease the renal uptake of 99mTc-RAD-Arg-(Arg11)CCMSH. 99mTc-RAD-Arg-(Arg11)CCMSH exhibited rapid and high tumor uptake (17.98 ± 4.96% ID/g at 2 h post-injection) in B16/F1 melanoma-bearing C57 mice. As compared to 99mTc-RAD-Lys-(Arg11)CCMSH, the replacement of the Lys linker with an Arg linker dramatically decreased the renal uptake of 99mTc-RAD-Arg-(Arg11)CCMSH by 68%, 62%, 73% and 64% at 0.5, 2, 4 and 24 h post-injection, respectively. Flank B16/F1 melanoma lesions were clearly imaged at 2 h post-injection using 99mTc-RAD-Arg-(Arg11)CCMSH as an imaging probe.