Biodistribution of iodine-125 labeled monoclonal antibody/interleukin-2 immunoconjugate in athymic mice bearing human tumor xenografts. 1997

K Nakamura, and A Kubo
Department of Radiology, Keio University School of Medicine, Tokyo, Japan.

BACKGROUND Some vasoactive drugs have been studied in the hope of altering the vascular permeability and/or blood of tumors to enhance monoclonal antibody (MoAb) uptake. The pretreatment of interleukin-2 (IL-2), one of the vasoactive reagents, produced a generalized vascular permeability, but its function was not tumor specific. Conversely, MoAb/IL-2 immunoconjugates were developed that selectively alter the vasopermeability of tumors. In the current study the authors evaluated whether radiolabeled anti-carcinoembryonic antigen (CEA) MoAb, ZCE025/IL-2 immunoconjugate, specifically can enhance delivery of iodine-125 (I-125) to tumor sites. METHODS ZCE025 was conjugated with IL-2, and the conjugate then labeled with I-125. Biodistribution studies were performed in athymic mice bearing CEA-producing human tumor (MKN45) xenografts. Mice were injected with I-125-ZCE025/IL-2 conjugate, and I-125 activities in the organs, including blood and tumor, were investigated at 1, 3, and 5 days after injection. Vascular permeability of the organs, including tumors, also was studied by using I-131 labeled mouse serum albumin in three groups. RESULTS I-125 labeled ZCE025/IL-2 conjugate destroyed its lymphokine-activated killer cell (LAK) activation, but retained a minimum of 75% of the antibody binding reactivity. Biodistribution of I-125-ZCE025/IL-2 conjugate showed increased uptake of I-125 in tumor by a factor of 1.5, 4.2, and 4.1 compared with I-125-ZCE025 on Days 1, 3, and 5, respectively. In contrast, I-125 distribution was not enhanced in any organs except the tumor. Vascular permeability studies demonstrated that the physiologic effect of IL-2 was tumor specific in the mice that received the I-125-ZCE025/IL-2 conjugate. CONCLUSIONS These studies indicate that the administration of radiolabeled MoAb/IL-2 double conjugate may enhance the therapeutic potential of radiolabeled MoAb without any pretreatment with IL-2 or repeated injection of MoAb.

UI MeSH Term Description Entries
D007376 Interleukin-2 A soluble substance elaborated by antigen- or mitogen-stimulated T-LYMPHOCYTES which induces DNA synthesis in naive lymphocytes. IL-2,Lymphocyte Mitogenic Factor,T-Cell Growth Factor,TCGF,IL2,Interleukin II,Interleukine 2,RU 49637,RU-49637,Ro-23-6019,Ro-236019,T-Cell Stimulating Factor,Thymocyte Stimulating Factor,Interleukin 2,Mitogenic Factor, Lymphocyte,RU49637,Ro 23 6019,Ro 236019,Ro236019,T Cell Growth Factor,T Cell Stimulating Factor
D007457 Iodine Radioisotopes Unstable isotopes of iodine that decay or disintegrate emitting radiation. I atoms with atomic weights 117-139, except I 127, are radioactive iodine isotopes. Radioisotopes, Iodine
D008819 Mice, Nude Mutant mice homozygous for the recessive gene "nude" which fail to develop a thymus. They are useful in tumor studies and studies on immune responses. Athymic Mice,Mice, Athymic,Nude Mice,Mouse, Athymic,Mouse, Nude,Athymic Mouse,Nude Mouse
D009368 Neoplasm Transplantation Experimental transplantation of neoplasms in laboratory animals for research purposes. Transplantation, Neoplasm,Neoplasm Transplantations,Transplantations, Neoplasm
D009374 Neoplasms, Experimental Experimentally induced new abnormal growth of TISSUES in animals to provide models for studying human neoplasms. Experimental Neoplasms,Experimental Neoplasm,Neoplasm, Experimental
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D000911 Antibodies, Monoclonal Antibodies produced by a single clone of cells. Monoclonal Antibodies,Monoclonal Antibody,Antibody, Monoclonal
D014018 Tissue Distribution Accumulation of a drug or chemical substance in various organs (including those not relevant to its pharmacologic or therapeutic action). This distribution depends on the blood flow or perfusion rate of the organ, the ability of the drug to penetrate organ membranes, tissue specificity, protein binding. The distribution is usually expressed as tissue to plasma ratios. Distribution, Tissue,Distributions, Tissue,Tissue Distributions
D014183 Transplantation, Heterologous Transplantation between animals of different species. Xenotransplantation,Heterograft Transplantation,Heterografting,Heterologous Transplantation,Xenograft Transplantation,Xenografting,Transplantation, Heterograft,Transplantation, Xenograft

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