title: Dual B- and T-cell de-immunization of recombinant immunotoxin targeting mesothelin with high cytotoxic activity.
abstract: Recombinant immunotoxins (RITs) are genetically engineered proteins being developed to treat cancer. They are composed of an Fv that targets a cancer antigen and a portion of a protein toxin. Their clinical success is limited by their immunogenicity. Our goal is to produce a new RIT that targets mesothelin and is non-immunogenic by combining mutations that decrease B- and T-cell epitopes. Starting with an immunotoxin that has B-cell epitopes suppressed, we added mutations step-wise that suppress T-cell epitopes. The final protein (LMB-T14) has greatly reduced antigenicity as assessed by binding to human anti-sera and a greatly decreased ability to activate helper T-cells evaluated in a T-cell activation assay. It is very cytotoxic to mesothelioma cells from patients, and to cancer cell lines. LMB-T14 produces complete remissions of a mesothelin expressing cancer (A431/H9) xenograft. The approach used here can be used to de-immunize other therapeutic foreign proteins.
authors.affiliation: Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Ronit
authors.initials: R
authors.lastname: Mazor
authors.affiliation: Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Masanori
authors.initials: M
authors.lastname: Onda
authors.affiliation: Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA.|New Business Development Department, Medytox Inc., Bundang-gu, Seongnam-si, Gyeonggi-do, South Korea.
authors.forename: Dong
authors.initials: D
authors.lastname: Park
authors.affiliation: Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Selamawit
authors.initials: S
authors.lastname: Addissie
authors.affiliation: Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Laiman
authors.initials: L
authors.lastname: Xiang
authors.affiliation: Thoracic and GI Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Jingli
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Thoracic and GI Oncology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Raffit
authors.initials: R
authors.lastname: Hassan
authors.affiliation: Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Ira
authors.initials: I
authors.lastname: Pastan
mesh_terms: D056704:Adaptive Immunity; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001427:Bacterial Toxins / Q000235:genetics / Q000276:immunology; D045744:Cell Line, Tumor; D018985:Epitopes, B-Lymphocyte / Q000235:genetics; D018984:Epitopes, T-Lymphocyte / Q000235:genetics; D005098:Exotoxins / Q000235:genetics / Q000276:immunology; D005260:Female; D058851:GPI-Linked Proteins / Q000037:antagonists & inhibitors*; D006801:Humans; D007135:Immunoglobulin Variable Region / Q000276:immunology; D007167:Immunotherapy / Q000379:methods; D000922:Immunotoxins / Q000235:genetics / Q000276:immunology* / Q000627:therapeutic use; D008175:Lung Neoplasms / Q000276:immunology / Q000628:therapy*; D000090204:Mesothelin; D008654:Mesothelioma / Q000276:immunology / Q000628:therapy*; D000086002:Mesothelioma, Malignant; D051379:Mice; D008819:Mice, Nude; D058990:Molecular Targeted Therapy / Q000379:methods; D009154:Mutation; D015202:Protein Engineering; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology* / Q000627:therapeutic use; D006377:T-Lymphocytes, Helper-Inducer; D023041:Xenograft Model Antitumor Assays
chemical_list: D000911:Antibodies, Monoclonal; D001427:Bacterial Toxins; D018985:Epitopes, B-Lymphocyte; D018984:Epitopes, T-Lymphocyte; D005098:Exotoxins; D058851:GPI-Linked Proteins; D007135:Immunoglobulin Variable Region; D000922:Immunotoxins; C000715528:Msln protein, mouse; D011993:Recombinant Fusion Proteins; D000090204:Mesothelin
keywords: epitope; immunogenicity; mesothelioma; pancreatic cancer; rational design