RT Journal Article SR Electronic T1 Absorbed doses from the Auger emitter antimony-119 (119Sb) in single tumor cells and clusters JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 241950 OP 241950 VO 65 IS supplement 2 A1 Champion, Christophe A1 Larouze, Alexandre A1 Alcocer Ávila, Mario Enrique A1 Morgat, Clement A1 Elif, Hindié YR 2024 UL http://jnm.snmjournals.org/content/65/supplement_2/241950.abstract AB 241950 Introduction: The early application of targeted radionuclide therapy (TRT) for eradicating tumor cell clusters and micrometastases might offer cure. However, it is essential to select suitable radionuclides and estimate the potential impact of non-uniform targeting. In this context, we investigated the absorbed radiation doses of antimony-119 (119Sb) in comparison to lutetium-177 (177Lu) considering the recent advances in production of this Auger electron emitter [1].Methods: The Monte Carlo code CELLDOSE was used to compute nuclear and membrane absorbed doses from 119Sb and 177Lu in single cells and in a cluster of 19 cells, each cell measuring 14 μm in diameter with 10 μm nucleus. The radionuclide distributions considered here were: cell surface, intracytoplasmic, or intranuclear, with 1436 MeV released per labeled cell. For non-uniform targeting, 12 cells at the periphery of the cluster were labeled, while the remaining seven cells were not.Results: In the case of single cell, and depending on radionuclide location, 119Sb delivered 17- to 22-fold higher nuclear absorbed dose than 177Lu and 18- to 48-fold higher cell membrane absorbed dose. For the cell cluster, when all 19 cells were targeted, 119Sb delivered 7- to 18-fold higher nuclear absorbed doses than 177Lu. However, 119Sb was more sensitive than 177Lu to heterogeneity in cell targeting. When the 12 cells at the periphery of the cluster were labeled, while the other cells were not (central cell and the 6 cells from the 1st neighborhood), the nucleus of the central cell received very low doses with 119Sb, and falling below those delivered by 177Lu in this situation. These results are explained by the pattern of energy deposit per disintegration of 119Sb. Indeed, 90% of 119Sb energy is deposited within a sphere of 7.1 µm-radius while the corresponding radius for 177Lu is 620 µm. Conclusions: In situations of uniform cell targeting, 119Sb may be a better candidate than 177Lu to eradicate single cells and homogeneous tumor clusters. However, 119Sb is highly sensitive to non-uniformity in cell targeting within tumor clusters.References: [1] Bennett KT et al., Large-Scale Production of 119mTe and 119Sb for Radiopharmaceutical Applications, ACS Cent. Sci, 2019, 5, 494–505