Using anti-GPA33 DOTA-PRIT as a model system, we showed that [225Ac]Pr or [111In]Pr could be pretargeted in vivo to GPA33-expressing human colorectal cancer SW1222 xenografts with radioactive uptakes in the range of 13-17 %IA/g for tumor, and with liver showing modest radioactive uptake for [225Ac]Pr (~1.5 %IA/g) and kidney (~1.0 %IA/g) for [111In]Pr. The gene discussed is GPA33; the disease is neoplasm.