title: Tumor cell targeting with antibody-avidin complexes and biotinylated tumor necrosis factor alpha.
abstract: Tumor pretargeting with biotinylated antibodies and avidin, followed by a delayed delivery of radioactive-labeled biotin, is currently used for in vivo diagnosis and therapy in cancer patients. Herein, we describe the use of a three-step antibody/avidin targeting approach to increase the local concentration and the persistence of biotinylated human tumor necrosis factor alpha (bio-TNF) on a mouse tumor. Mouse RMA lymphoma cells were transfected with the Thy 1.1 allele (RMA-Thy 1.1) to generate a unique tumor-associated antigen. In vitro pretargeting of RMA-Thy 1.1 cells with the biotinylated anti-Thy 1.1 monoclonal antibody 19E12 (bio-19E12) and NeutrAvidin increased the amount of bio-TNF that bound to the cell (10-20 times in comparison with non-pretargeted cells), as well as its half-life on the surface (>30 times). Furthermore, cell pretargeting reduced by more than 2 orders of magnitude the LD50 of bio-TNF in a cytolytic assay with actinomycin D. Finally, RMA-Thy 1.1 cells, pretreated in vitro with bio-TNF according to the three-step procedure and injected into syngeneic C57/BL6 mice, were less tumorigenic than controls. These results indicate that the three-step targeting approach markedly increases the amount and the persistence of bio-TNF on the cell surface and that cell-bound bio-TNF can trigger cytolytic effects in vitro and antitumor effects in vivo. Tumor pretargeting with biotinylated antibodies and avidin could be a novel strategy for increasing the therapeutic index of TNF.
authors.affiliation: Dipartimento di Ricerca Biologica e Tecnologia, San Raffaele Hospital Scientific Institute, Milan, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Moro
authors.forename: M
authors.initials: M
authors.lastname: Pelagi
authors.forename: G
authors.initials: G
authors.lastname: Fulci
authors.forename: G
authors.initials: G
authors.lastname: Paganelli
authors.forename: P
authors.initials: P
authors.lastname: Dellabona
authors.forename: G
authors.initials: G
authors.lastname: Casorati
authors.forename: A G
authors.initials: AG
authors.lastname: Siccardi
authors.forename: A
authors.initials: A
authors.lastname: Corti
mesh_terms: D000818:Animals; D000906:Antibodies / Q000378:metabolism*; D001360:Avidin / Q000378:metabolism / Q000493:pharmacokinetics*; D001710:Biotin / Q000378:metabolism / Q000493:pharmacokinetics*; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D018796:Immunoconjugates / Q000378:metabolism / Q000493:pharmacokinetics*; D000922:Immunotoxins / Q000378:metabolism / Q000493:pharmacokinetics*; D008223:Lymphoma / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000493:pharmacokinetics*
chemical_list: D000906:Antibodies; D018796:Immunoconjugates; D000922:Immunotoxins; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D001360:Avidin; D001710:Biotin