Zirconium-89 labeled antibodies: a new tool for molecular imaging in cancer patients

Antibody based positron emission tomography (immuno-PET) imaging is of increasing importance to visualize and characterize tumor lesions. Additionally, it can be used to identify patients who may benefit from a particular therapy and monitor the therapy outcome. In recent years the field is focused on (89)Zr, a radiometal with near ideal physical and chemical properties for immuno-PET. In this review we will discuss the production of  (89)Zr, the bioconjugation strategies, and applications in (pre-)clinical studies of  (89)Zr-based immuno-PET in oncology. To date, (89)Zr-based PET imaging has been investigated in a wide variety of cancer-related targets. Moreover, clinical studies have shown the feasibility for (89)Zr-based immuno-PET to predict and monitor treatment, which could be used to tailor treatment for the individual patient. Further research should be directed towards the development of standardized and robust conjugation methods and improved chelators to minimize the amount of released Zr(4+) from the antibodies. Additionally, further validation of the imaging method is required. The ongoing development of new (89)Zr-labeled antibodies directed against novel tumor targets is expected to expand applications of  (89)Zr-labeled immuno-PET to a valuable method in the medical imaging.