title: A novel CD19-directed recombinant bispecific antibody derivative with enhanced immune effector functions for human leukemic cells.
abstract: A novel bispecific antibody-derived recombinant protein targeting leukemias and lymphomas was designed, a single-chain Fv triple body (sctb) consisting of 1 polypeptide chain with 3 scFvs connected in tandem. The distal scFvs were specific for the tumor antigen CD19, and the central scFv for the trigger molecule CD16 (FcgammaRIII) on natural killer (NK) cells and macrophages. We had previously built a disulphide stabilized (ds) bsscFv [19 x 16] with monovalent binding for CD19 from ds components. The sctb ds[19 x 16 x 19] also used ds components and displayed 3-fold greater avidity for CD19 than the bsscFv (KD = 13 vs. 42 nM), whereas both had equal affinity for CD16 (KD = 58 nM). Plasma half-lives in mice were 4 and 2 hours for the sctb and the bsscFv, respectively. In antibody-dependent cellular cytotoxicity reactions with human mononuclear cells as effectors, the sctb promoted equal lysis of leukemic cell lines and primary cells from leukemia and lymphoma patients at 10-fold to 40-fold lower concentrations than the bsscFv. This new format may also be applicable to a variety of other tumor antigens and effector molecules. With half-maximum effective concentrations (EC50) in the low picomolar range, the sctb ds[19 x 16 x 19] is an attractive candidate for further preclinical evaluation.
authors.affiliation: Chair of Genetics, University of Erlangen-Nuremberg, BTE-building, Erwin-Rommel Strasse 3, D-91058 Erlangen, Germany. ckellner@biologie.uni-erlangen.de
authors.forename: Christian
authors.initials: C
authors.lastname: Kellner
authors.forename: Joerg
authors.initials: J
authors.lastname: Bruenke
authors.forename: Julia
authors.initials: J
authors.lastname: Stieglmaier
authors.forename: Michael
authors.initials: M
authors.lastname: Schwemmlein
authors.forename: Michael
authors.initials: M
authors.lastname: Schwenkert
authors.forename: Heiko
authors.initials: H
authors.lastname: Singer
authors.forename: Kristin
authors.initials: K
authors.lastname: Mentz
authors.forename: Matthias
authors.initials: M
authors.lastname: Peipp
authors.forename: Peter
authors.initials: P
authors.lastname: Lang
authors.forename: Fuat
authors.initials: F
authors.lastname: Oduncu
authors.forename: Bernhard
authors.initials: B
authors.lastname: Stockmeyer
authors.forename: Georg H
authors.initials: GH
authors.lastname: Fey
mesh_terms: D000818:Animals; D018033:Antibodies, Bispecific / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000627:therapeutic use; D000920:Antibody-Dependent Cell Cytotoxicity; D018941:Antigens, CD19 / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D016466:CHO Cells; D003001:Cloning, Molecular; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D007128:Immunoglobulin Fragments / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000378:metabolism / Q000627:therapeutic use; D007167:Immunotherapy; D007694:Killer Cells, Natural / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D007938:Leukemia / Q000276:immunology / Q000473:pathology / Q000628:therapy*; D008264:Macrophages / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D008297:Male; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D017452:Receptors, IgG / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism / Q000627:therapeutic use
chemical_list: D018033:Antibodies, Bispecific; D018941:Antigens, CD19; D007128:Immunoglobulin Fragments; D017452:Receptors, IgG; D011993:Recombinant Fusion Proteins