Conjugation and radiolabeling of monoclonal antibodies with zirconium-89 for PET imaging using the bifunctional chelate p-isothiocyanatobenzyl-desferrioxamine

The positron emitter zirconium-89 (Zr-89) has very attractive properties for positron emission tomography (PET) imaging of intact monoclonal antibodies (mAbs) using immuno-PET. This protocol describes the step-by-step procedure for the facile radiolabeling of mAbs or other proteins with Zr-89 using p-isothiocyanatobenzyl-desferrioxamine (Df-Bz-NCS). First, Df-Bz-NCS is coupled to the lysine-NH2 groups of a mAb at pH 9.0 (pre-modification), followed by purification using gel filtration. Next, the pre-modified mAb is labeled at room temperature by the addition of [Zr-89] Zr-oxalic acid solution followed by purification using gel filtration. The entire process of pre-modification, radiolabeling and purification steps will take about 2.5 h.