title: Recombinant single-chain and disulfide-stabilized Fv-immunotoxins that cause complete regression of a human colon cancer xenograft in nude mice.
abstract: Monoclonal antibody (MAb) 55.1 specifically recognizes an antigen on the surface of human colon adenocarcinoma cells. We constructed recombinant immunotoxins composed of the heavy- and light-chain variable regions of MAb 55.1 fused to a recombinant form of Pseudomonas exotoxin (PE). The heavy- and light-chain variable regions are stabilized by 2 means. One is by a flexible peptide linker to form a single-chain antigen binding protein (scFv) and the second by an interchain disulfide bond engineered between structurally conserved framework regions. These are termed disulfide stabilized Fvs (dsFv). The 2 Fv forms are fused to truncated forms of PE lacking the cell binding domain. The recombinant scFv- and dsFv-immunotoxins were expressed in E. coli and purified to near homogeneity. The scFv- and dsFv-immunotoxins were shown to be specifically cytotoxic to human colon adenocarcinoma cell lines. The scFv-immunotoxin containing PE38KDEL was more active than the immunotoxin containing PE38 with the native carboxyl terminus (REDLK). However, the PE38KDEL immunotoxin is about 2-fold more toxic in mice, and therefore it does not appreciably increase the therapeutic window in mice. Intravenous administration of the scFv- and dsFv- recombinant immunotoxins caused complete regression of a human colon carcinoma (Colo205) growing subcutaneously in immunodeficient mice. The dsFv-immunotoxin has better antitumor activity compared with its scFv-immunotoxin counterpart.
authors.affiliation: Laboratory of Molecular Biology, Division of Basic Sciences, National Cancer Institute, National Insitutes of Health, Bethesda, MD 20892-4255, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Reiter
authors.forename: A F
authors.initials: AF
authors.lastname: Wright
authors.forename: D W
authors.initials: DW
authors.lastname: Tonge
authors.forename: I
authors.initials: I
authors.lastname: Pastan
mesh_terms: D036002:ADP Ribose Transferases; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000627:therapeutic use; D001427:Bacterial Toxins; D001483:Base Sequence; D003110:Colonic Neoplasms / Q000628:therapy*; D005098:Exotoxins / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D007128:Immunoglobulin Fragments / Q000627:therapeutic use*; D000922:Immunotoxins / Q000627:therapeutic use*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D008969:Molecular Sequence Data; D009368:Neoplasm Transplantation; D011994:Recombinant Proteins / Q000627:therapeutic use; D014183:Transplantation, Heterologous; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A
chemical_list: D036002:ADP Ribose Transferases; D000911:Antibodies, Monoclonal; D001427:Bacterial Toxins; D005098:Exotoxins; D007128:Immunoglobulin Fragments; D000922:Immunotoxins; D011994:Recombinant Proteins; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A; C055966:immunoglobulin Fv