title: A dual-targeting triplebody mediates preferential redirected lysis of antigen double-positive over single-positive leukemic cells.
abstract: The single-chain triplebody HLA-ds16-hu19 consists of three single-chain Fv (scFv) antibody fragments connected in a single polypeptide chain. This protein with dual-targeting capacity mediated preferential lysis of antigen double positive(dp) over single-positive (sp) leukemic cells by recruitment of natural killer (NK) cells as effectors. The two distal scFv modules were specific for the histocompatibility protein HLA-DR and the lymphoid antigen CD19, the central one for the Fc gamma receptor CD16. In antibody-dependent cellular cytotoxicity (ADCC) experiments with a mixture of leukemic target cells comprising both HLA-DR sp HuT-78 or Kasumi-1 cells and (HLA-DR plus CD19) dp SEM cells, the triplebody mediated preferential lysis of the dp cells even when the sp cells were present in ≤ 20-fold numerical excess.The triplebody promoted equal lysis of SEM cells at 2.5-fold and 19.5-fold lower concentrations than the parental antibodies specific for HLA-DR and CD19, respectively. Finally, the triplebody also eliminated primary leukemic cells at lower concentrations than an equimolar mixture of bispecific single-chain Fv fragments (bsscFvs) separately addressing each target antigen (hu19-ds16 and HLA-ds16). The increased selectivity of targeting and the preferential lysis of dp over sp cells achieved by dual-targeting open attractive new perspectives for the use of dual-targeting agents in cancer therapy.
authors.forename: Ingo
authors.initials: I
authors.lastname: Schubert
authors.forename: Domenica
authors.initials: D
authors.lastname: Saul
authors.forename: Stefanie
authors.initials: S
authors.lastname: Nowecki
authors.forename: Andreas
authors.initials: A
authors.lastname: Mackensen
authors.forename: Georg H
authors.initials: GH
authors.lastname: Fey
authors.forename: Fuat S
authors.initials: FS
authors.lastname: Oduncu
mesh_terms: D000818:Animals; D000912:Antibodies, Neoplasm / Q000235:genetics / Q000276:immunology / Q000494:pharmacology*; D018941:Antigens, CD19 / Q000235:genetics / Q000276:immunology*; D000970:Antineoplastic Agents / Q000276:immunology / Q000494:pharmacology*; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D016503:Drug Delivery Systems; D005260:Female; D006684:HLA-DR Antigens / Q000235:genetics / Q000276:immunology*; D006801:Humans; D007111:Immunity, Cellular / Q000187:drug effects* / Q000276:immunology; D007694:Killer Cells, Natural / Q000276:immunology* / Q000473:pathology; D008297:Male; D009363:Neoplasm Proteins / Q000276:immunology*; D057127:Single-Chain Antibodies / Q000235:genetics / Q000276:immunology / Q000494:pharmacology*
chemical_list: D000912:Antibodies, Neoplasm; D018941:Antigens, CD19; D000970:Antineoplastic Agents; D006684:HLA-DR Antigens; D009363:Neoplasm Proteins; D057127:Single-Chain Antibodies