The co-injection of [D-Phe6,Leu-NHEt13,des-Met14]Bombesin(6–14) reduced the uptake of [68Ga]Ga-TacBOMB2 in PC-3 tumor xenografts by 85% (from 5.95 ± 0.50 to 0.92 ± 0.22%ID/g, p < 0.01) at 1 h post-injection. The gene discussed is GRP; the disease is neoplasm.