(89)Zr-Immuno-Positron Emission Tomography in Oncology: State-of-the-Art (89)Zr Radiochemistry

[Image: see text] Immuno-positron emission tomography (immunoPET) with (89)Zr-labeled antibodies has shown great potential in cancer imaging. It can provide important information about the pharmacokinetics and tumor-targeting properties of monoclonal antibodies and may help in anticipating on toxicity. Furthermore, it allows accurate dose planning for individualized radioimmunotherapy and may aid in patient selection and early-response monitoring for targeted therapies. The most commonly used chelator for (89)Zr is desferrioxamine (DFO). Preclinical studies have shown that DFO is not an ideal chelator because the (89)Zr–DFO complex is partly unstable in vivo, which results in the release of (89)Zr from the chelator and the subsequent accumulation of (89)Zr in bone. This bone accumulation interferes with accurate interpretation and quantification of bone uptake on PET images. Therefore, there is a need for novel chelators that allow more stable complexation of (89)Zr. In this Review, we will describe the most recent developments in (89)Zr radiochemistry, including novel chelators and site-specific conjugation methods.