Dual-isotope SPECT/CT imaging of hematopoietic stem cell humanized NSG mice (HSC-NSG) bearing a human gastric adenocarcinoma xenograft tumor (MKN-45, displaying high CEA expression) showed tumor targeting and uptake of 111In-CEA-TCB apparent at 4 h post-antibody injection, which continued to increase up to 120 h post single antibody injection (Supplementary Figure 1A). Here, CEACAM5 is linked to neoplasm.