Random and site-specific radiolabeling of [⁸⁹Zr]Zr-DFO-anti-PD-L1-mAb iPET tracer

Zirconium-89 radiolabeled immuno-positron emission tomography (Zr-89-iPET) has become a critical tool for patient stratification before and after immunotherapies for therapeutic evaluation. In this study, random and site-specific radiolabeling of Zr-89-iPET tracers were investigated. Traditional lysine-based conjugation and enzyme-based GlyCLICK (R) kit method were used to prepare DFO-anti-PD-L1-mAb conjugates with a chelator-to-antibody ratio (CAR) of 0-7 and 2.0, respectively. Then, conjugates with different CAR levels were radiolabeled with Zr-89 to obtain randomly or site-specifically radiolabeled Zr-89-iPET tracer.