Probes for radiotheranostics could
be produced by introducing radionuclides
with similar chemical characteristics into the same precursors. We
recently developed an 211At-labeled RGD peptide and a corresponding
radioiodine-labeled RGD peptide. Both labeled peptides accumulated
in large quantities in the tumor with similar biodistribution, demonstrating
their usefulness for radiotheranostics. In this study, we hypothesized
that probes for radiotheranostics combined with multiradionuclides,
such as 68Ga and 211At, have useful clinical
applications. New radiolabeled RGD peptide probes were synthesized
via a molecular design approach, with two labeling sites for metal
and halogen. These probes were evaluated in biodistribution experiments
using tumor-bearing mice. [67Ga]Ga-DOTA-c[RGDf(4-I)K] ([67Ga]4), Ga-DOTA-[125I]c[RGDf(4-I)K]
([125I]4), and Ga-DOTA-[211At]c[RGDf(4-At)K]
([211At]7) showed similar biodistribution,
with high and equivalent accumulation in tumors. These results indicate
the usefulness of these probes in radiotheranostics with multiradionuclides,
such as a radiometal and a radiohalogen, and they could contribute
to a personalized medicine regimen.