Advanced gastric cancer is the third leading cause of cancer related deaths worldwide. A host of monoclonal antibodies (mAbs), which are highly selective, are now approved for cancer therapy. However, there is a need to determine whether these therapeutic mAbs are effective. In order to evaluate their efficacy mAbs are labeled with radioisotopes and used as imaging agents. The labeled mAbs are then tested against patient specific organoids and tumor models, which are personalized cancer models, to visually observe drug sensitivity, uptake, and effectiveness. Due to the slow distribution kinetics of these antibodies, typically on the order of days, potential candidates for radiolabeling must possess comparable physical half-lives.72As, a potential positron emission tomography (PET) radionuclide, is well suited due to its appropriate half-life, 26 hours, and ease of accessibility through the use of a portable generator. This portable 72Se/72As generator can be milked every 3-5 days to produce material for over one month. In this study 72As was produced using a metal arsenic target at the Brookhaven LINAC Isotope Producer (BLIP). 72Se was separated from co-produced material and loaded onto the generator. The potential generator was optimized and evaluated for breakthrough of the parent isotope. Monoclonal antibodies were labeled with 72As through the use of a trithiol chelating ligand. Initial in vivo images in patient-derived tumor xenografted mice show that non-specific antibodies do not have uptake at the tumor location. Further studies will be completed with tumor specific antibodies to determine tumor uptake and to assess mAb therapies.

72As a candidate for PET imaging: From production to in vivo imaging

255th National Meeting (2018)

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