Lifting Fc/FcRn interaction for brain PET imaging. We evaluated the potency of anti-PD-L1 IgGs with low affinity for the FcRn receptor for brain PET imaging by comparing the kinetics of 89Zr-DFO-C4 and 89Zr-DFO-C4Fc-MUT in an orthotopic syngeneic mouse model of GBM. Here, CD274 is linked to glioblastoma.