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Dosimetry of fractionated administration of 125 I‐labeled antibody at experimental radioimmunotargeting
Author(s) -
Ullén Anders,
Sandström Per,
Norrlund Rauni Rossi,
Rathsman Sandra,
Johansson Lennart,
Åhlström Katrine Riklund,
Hietala SvenOla,
Stigbrand Torgny
Publication year - 1997
Publication title -
cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.052
H-Index - 304
eISSN - 1097-0142
pISSN - 0008-543X
DOI - 10.1002/(sici)1097-0142(19971215)80:12+<2510::aid-cncr25>3.0.co;2-e
Subject(s) - radioimmunotherapy , medicine , nuclear medicine , bolus (digestion) , dosimetry , pharmacokinetics , antibody , monoclonal antibody , pharmacology , immunology
BACKGROUND Radiotherapy of solid tumors is preferably performed in fractionated doses. Conversely, radioimmunotherapy with nuclide‐carrying antibodies delivers a continuously decreasing low dose rate during a longer time period after a single injection. In the current study, the same total amount of 125 I‐labeled anticytokeratin monoclonal antibody (MoAb) was administrated in one, three, or ten injections and the dosimetry was evaluated. METHODS Three groups of nude mice (10 mice each) with HeLa Hep 2 xenografts were injected with 1 × 100 μg/22.2 megabecquerel (MBq), 3 × 33 μg/7.4 MBq, and 10 × 10 μg/2.22 MBq 125 I‐labeled TS1 MoAb, respectively. The mice were examined scintigraphically over a 54‐day period (total number of radio immunoscintigraphies (RISs) = approximately 700) and doses to tumor and normal tissues were estimated according to the medical internal radiation dose formalism. RESULTS A single bolus injection caused higher tumor uptake, tumor dose, and tumor to nontumor dose ratio than administration of the same total dose of antibody and radioactivity in three or ten separate injections. The single bolus injection caused a tenfold higher tumor uptake (% injected dose, or ID) compared with the group receiving ten injections. This caused a tumor dose of 17 gray to the group receiving a single bolus injection. CONCLUSIONS In this antigen target system, a single injection of a large amount of antibody was found to be more efficient than the same antibody dose subdivided into three or ten fractions. It was concluded that not only the radioactivity but also the amount of antibody per fraction should be considered when determining optimal fractionated radioimmunotherapy. Cancer 1997; 80:2510‐8. © 1997 American Cancer Society.