The model system assembled for this investigation was composed of (1) the huA33 antibody, an mAb that targets the A33 antigen expressed on >95% of colorectal cancers; (2) 89Zr, a positron-emitting radiometal whose 3.3 d physical half-life aligns well with the multi-day serum residence times of IgGs; (3) a TCO-bearing variant of desferrioxamine (TCO-DFO), an acyclic chelator that provides Zr4+ with an oxygen-rich, kinetically inert, and thermodynamically stable coordination environment; and (4) the A33 antigen-expressing SW1222 human colorectal cancer cell line. Here, GPA33 is linked to colorectal cancer.