The use of [(125)I] scintigraphic in vivo imaging in melanoma-bearing mice for a rapid prescreening of vectors to melanoma tissue.

ABSTRACT

INTRODUCTION: The use of radiolabeled molecules allows the study of in vivo biodistribution, target organs, and kinetic profile after systemic administration by 1) radioactive organ counting and 2) quantitative autoradiographic analysis of whole-body slices (WBA). However, these techniques are time- and animal consuming for several times studied. So, in vivo scintigraphic imaging should appear of interest for a first screening of compounds, as it is able to rapidly demonstrate tumoral uptake and kinetics by serial examinations in the same mice. MATERIALS AND METHODS: In this study, the tumoral distribution and kinetics of six molecules considered as potential melanoma tracers radiolabeled with (125)I were analyzed by gamma-scintigraphy comparatively to the results obtained by WBA. Tumoral uptake has been quantified and expressed by 1) tumor-to-background ratios and 2) standardized tumoral uptake (STU) in percent injected dose per gram, with tumor weight being extrapolated from the measurement of the two diameters. RESULTS: Results from STU analysis showed good agreement (correlation coefficient = 0.92) with those of WBA, and the same classification of compounds (on the basis of their melanoma affinity) was obtained, with two compounds (of six) being rejected. CONCLUSIONS: [(125)I] scintigraphic imaging appeared as a relevant, easy-going method for a first pharmacologic selection in mice.