Fully automated radiosynthesis of [11C]PBR28, a radiopharmaceutical for the translocator protein (TSPO) 18 kDa, using a GE TRACERlab FXC-Pro

Abstract

In order to image the translocator protein (TSPO) 18kDa in the clinic using positron emission tomography (PET) imaging, we had a cause to prepare [11C]PBR28. In this communication we highlight our novel, recently developed, one-pot synthesis of the desmethyl-PBR28 precursor, as well as present an optimized fully automated preparation of [11C]PBR28 using a GE TRACERlab FXC-Pro. Following radiolabelling, purification is achieved by HPLC and, to the best of our knowledge, the first reported example of reconstituting [11C]PBR28 into ethanolic saline using solid-phase extraction (SPE). This procedure is operationally simple, and provides high quality doses of [11C]PBR28 suitable for use in clinical PET imaging studies. Typical radiochemical yield using the optimized method is 3.6% yield (EOS, n=3), radiochemical and chemical purity are consistently >99%, and specific activities are 14,523Ci/mmol.