Authors
Lars Perk, Gerard Visser, Marianne Budde, Maria Vosjan, Paul Jurek, Garry Kiefer, and Guus van Dongen
Summary
Presently, hundreds of monoclonal antibodies (mAbs) and mAb fragments are under clinical development because of their excellent potential for the systemic treatment of cancer and other pathological conditions1, 2. Positron emission tomography (PET) offers an exciting imaging option to confirm and quantify selective tumor uptake of such targeting molecules3. To enable PET imaging of mAbs (immuno-PET), an appropriate positron emitter, with a half-life (t1/2) that is compatible with the time needed to achieve optimal tumor-to-nontumor ratios (typically 2-4 days for intact mAbs), has to be securely coupled to the targeting molecule. For this purpose we recently described the large scale production of pure zirconium-89 (89Zr; t1/2: 78.4 h) and a strategy for labeling mAbs with 89Zr via a multi-step synthesis using a succinylated-derivative of desferrioxamine B (Df) as bifunctional chelate4. The utility of this approach was clearly demonstrated through high quality 89Zr-mAb-PET images reported in preclinical and clinical studies5-11. The upcoming commercialization of 89Zr will make this radionuclide generally available for research and clinical development. A shortcoming of the aforementioned approach is that the multi-step procedure is relatively complicated and time consuming. In this updated protocol we present the newly developed p-isothiocyanatobenzyl-derivative of Df (SCN-Bz-Df; Macrocyclics, TX) which provides an efficient and rapid preparation of 89Zr-labeled mAbs. First, SCN-Bz-Df is coupled to the amine groups of a protein at pH 9.0, followed by purification using gel filtration. Next, the conjugate is labeled at room temperature by addition of a solution of 89Zr oxalic acid followed by purification using gel filtration. SCN-Bz-Df can also be utilized to label proteins at room temperature with gallium-68 (68Ga; t1/2: 1.13 h). 68Ga is especially attractive for PET-imaging of fast kinetic targeting proteins like mAb fragments.Further details
The protocol was published on Protocol Exchange in 2008. To see the entire protocol, click on the source link.Advertisement
Stats
- Recommendations n/a n/a positive of 0 vote(s)
- Views 708
- Comments 0