In particular, the compound DOTA-Aoc-BBN(7–14) (Figure 4, 1), bearing the 8-carbons linker (Aoc: 8-Aminooctanoic Acid), showed an IC50 value in the low nanomolar range (6.7 ± 1.1 nM) and a quick internalization (1,419 ± 109 fmol/mg after 4 h) in the human BC cell line T47D, that expresses both GRPR and ER. This evidence concerns the gene ESR1 and breast cancer.