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TAT-11: Pharmacokinetic Variability of In Vivo Generated 213Bi and Vector Labeled Ac-225 in Murine Cancer Models

Ottawa, ON, Canada (UroToday.com) In Ac225 therapy, there is a known problem when decay daughters are released from the labeled vector by the recoil of the first alpha decay. The daughter Bi213 h46-minute half-life, enough time to be distributed in the body with potential harm to healthy tissue. Dr, Josefsson reported on a study in mice to trace the distribution of both the Ac225-labeled vector and the free Bi213. The Ac225 was conjugated to three different antibodies corresponding to the mouse tumors: 7.16.4 antibodies for breast cancer, anti-VLA-4 antibodies for melanoma, and PSMAcastrate-resistant prostate cancer. The mice were sacrificed at specific times after injection and the blood, liver, ki, neys and spleen harvested and counted in a gamma well. The Ac and Bi contents were measured by fitting to the known lifetimes. All models showed Bi213 accumulation in the kidneys. The distribution within the kidney was not the same—uniform for the 7.16.4 labeled antibody but non-uniform for the other two and the free Bi213.


Presented by: Anders Josefsson, Ph.D., Johns Hopkins University School of Medicine, Baltimore, Maryland