Optimization of Chelator Conjugation to PD-1/VEGF Bispecific Antibody for 89 Zr-ImmunoPET Imaging

PD-1/PD-L1 and VEGF pathways jointly mediate T-cell dysfunction and immune suppression, limiting the efficacy of immune checkpoint inhibitors. We developed an ⁸⁹Zr-labeled bispecific immuno-PET probe, ⁸⁹Zr-JS207, for noninvasive imaging of PD-1 and VEGF in tumors. ⁸⁹Zr-JS207 was prepared via <i>p</i>-isothiocyanatobenzyl-desferrioxamine (<i>p</i>-NCS-Bz-DFO) conjugation with high radiochemical purity (>99%) and excellent in vitro stability (>95% at 240 h). It sho