EGF-receptors (EGFR) are overexpressed in
gliomas, as well as in
tumors of breast, lung, and urinary bladder. For this reason, EGFR may be an attractive target for both visualization and
therapy of malignant
tumors using radioactive nuclides. Natural
ligand of EGFR,
epidermal growth factor (
EGF) is a small 53-amino-acid
protein. Low molecular weight of
EGF may enable better intratumoral penetration in comparison to
antibodies. [111In]
DTPA-
EGF was proposed for the targeting of
glioblastoma and
breast cancer, and its
tumor-seeking properties were confirmed in animal studies. The aim of this study was to evaluate how the substitution of heptadentate
DTPA for octadentate
benzyl-DTPA (Bz-
DTPA) effects the biodistribution of
indium-labeled human
EGF (hEGF) in normal NMRI mice. [111In]
DTPA-hEGF and [111In]Bz-
DTPA-hEGF, obtained by the coupling of ITC-
benzyl-DTPA to hEGF, were injected into the tail vein. At 0.5, 1, 4, and 24 hours postinjection, the animals were sacrificed, and radioactivity in different organs was measured. The blood clearance of both conjugates was fast. The uptake of both conjugates in the liver, spleen, stomach, pancreas, intestines, and submaxillary gland was most likely receptor-mediated. The uptake in a majority of organs was similar. However,
indium uptake in the case of [111In]
DTPA-hEGF was significantly higher in the kidneys and bones. In conclusion, [111In]Bz-
DTPA-hEGF seems to have more favourable in vivo distribution in comparison to [111In]
DTPA-hEGF.