Zr-89-labelled Obinutuzumab: a potential immuno-PET radiopharmaceutical

Obinutuzumab (Obi) is a clinically approved a next-generation monoclonal antibody (mAb), showing specific binding to the CD20 B-cell surface markers which is a key target for B-cell malignancies. In this study, Zr-89-labelling Obi was optimised and the binding of the labelled agent was validated in an in-vitro model. Obi was radiolabelled with Zr-89 with several different ratios to optimise the (mAb: DFO-Bz-NCS: Zr-89) ratio with a small amount of it. The reason to employ the antibody as low quantity as possible in radiolabelling studies was the very high cost of antibodies. The radiolabelling studies were followed by in-vitro studies that would demonstrate the affinity of the formulations to the cells of CD20(+). Proving the specificity of Zr-89-Obi may be beneficial in diagnosing and monitoring CD20(+) tumours. Obi's long half-life and high sensitivity to CD20 are important in this area.