GPA33 and neoplasm: These radioligands were paired with a TCO-bearing variant of the A33 antigen-targeting antibody huA33 (i.e., huA33-TCO) for pretargeted immunoPET in a murine model of colorectal cancer, revealing that all three produced images with excellent tumor-to-background contrast, but [<sup>64</sup>Cu]Cu-SarAr-PEG<sub>10</sub>-Tz yielded the best tumor-to-tissue activity concentration ratios.