title: A potent and specific immunotoxin for tumor cells expressing disialoganglioside GD2.
abstract: Monoclonal antibody 14G2a (anti-GD2) reacts with cell lines and tumor tissues of neuroectodermal origin that express disialoganglioside GD2. mAb 14G2a was coupled to the ribosome-inactivating plant toxin gelonin with the heterobifunctional cross-linking reagent N-succinimidyl-3(2-pyridyldithio)propionate. The activity of the immunotoxin was assessed by a cell-free translation assay that confirmed the presence of active gelonin coupled to 14G2a. Data from an enzyme-linked immunosorbent assay demonstrated the specificity and immunoreactivity of the 14G2a-gelonin immunotoxin, which was identical to that of native 14G2a. Assays for complement-dependent cytotoxicity (CDC) and antibody-dependent cellular cytotoxicity (ADCC) revealed that these functional properties of the native 14G2a antibody were also preserved in the 14G2a-gelonin immunotoxin. The gelonin-14G2a immunotoxin was directly cytotoxic to human melanoma (A375-M and AAB-527) cells and was 1000-fold more active than native gelonin in inhibiting the growth of human melanoma cells in vitro. The augmentation of tumor cell killing of 14G2a-gelonin immunotoxin was examined with several lysosomotropic compounds. Chloroquine and monensin, when combined with 14G2a-gelonin immunotoxin, augmented its cytotoxicity more than 10-fold. Biological response modifiers such as tumor necrosis factor alpha and interferon alpha and chemotherapeutic agents such as cisplatinum and N,N'-bis(2-chloroethyl)-N-nitrosourea (carmustine) augmented the cytotoxicity of 14G2a-gelonin 4- to 5-fold. The results of these studies suggest that 14G2a-gelonin may operate directly by both cytotoxic efforts and indirectly by mediating both ADCC and CDC activity against tumor cells; thus it may prove useful in the future for therapy of human neuroectodermal tumors.
authors.affiliation: Department of Clinical Immunology and Biological Therapy, M. D. Anderson Cancer Center, Houston, Texas 77030.
authors.forename: K
authors.initials: K
authors.lastname: Mujoo
authors.forename: R A
authors.initials: RA
authors.lastname: Reisfeld
authors.forename: L
authors.initials: L
authors.lastname: Cheung
authors.forename: M G
authors.initials: MG
authors.lastname: Rosenblum
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology; D000918:Antibody Specificity; D000920:Antibody-Dependent Cell Cytotoxicity; D000970:Antineoplastic Agents / Q000494:pharmacology; D003165:Complement System Proteins / Q000502:physiology; D005732:Gangliosides / Q000276:immunology / Q000502:physiology*; D006801:Humans; D007155:Immunologic Factors / Q000494:pharmacology; D000922:Immunotoxins / Q000276:immunology*; D008247:Lysosomes / Q000378:metabolism; D008545:Melanoma / Q000188:drug therapy / Q000276:immunology* / Q000473:pathology; D008985:Monensin / Q000494:pharmacology; D010940:Plant Proteins / Q000494:pharmacology*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology*; D054789:Ribosome Inactivating Proteins, Type 1; D014407:Tumor Cells, Cultured / Q000187:drug effects
chemical_list: D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; D005732:Gangliosides; D007155:Immunologic Factors; D000922:Immunotoxins; D010940:Plant Proteins; D011500:Protein Synthesis Inhibitors; D054789:Ribosome Inactivating Proteins, Type 1; C019403:ganglioside, GD2; C025674:GEL protein, Gelonium multiflorum; D003165:Complement System Proteins; D008985:Monensin