Antibody-based PET imaging of amyloid beta in mouse models of Alzheimer’s disease

Owing to their specificity and high-affinity binding, monoclonal antibodies have potential as positron emission tomography (PET) radioligands and are currently used to image various targets in peripheral organs. However, in the central nervous system, antibody uptake is limited by the blood–brain barrier (BBB). Here we present a PET ligand to be used for diagnosis and evaluation of treatment effects in Alzheimer’s disease. The amyloid β (Aβ) antibody mAb158 is radiolabelled and conjugated to a transferrin receptor antibody to enable receptor-mediated transcytosis across the BBB. PET imaging of two different mouse models with Aβ pathology clearly visualize Aβ in the brain. The PET signal increases with age and correlates closely with brain Aβ levels. Thus, we demonstrate that antibody-based PET ligands can be successfully used for brain imaging. Imaging tools for evaluating progression of Alzheimer’s disease have been lacking. Here the authors develop a blood brain barrier-permeable Aß probe based on a radiolabelled, anti-Aß antibody, and report age-dependent brain uptake visualized in vivo with PET in mouse models of the disease.