Potent Therapeutic Activity Against Peritoneal Dissemination and Malignant Ascites by the Novel Anti-Folate Receptor Alpha Antibody KHK2805.

Many ovarian cancer patients often show peritoneal metastasis with malignant ascites. However, unmet medical needs remain regarding controlling these symptoms after tumors become resistant to chemotherapies. We developed KHK2805, a novel anti-folate receptor α (FOLR1) humanized antibody with enhanced antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC).

Cell Surface Antibody Retention Influences In Vivo Antitumor Activity Mediated by Antibody-dependent Cellular Cytotoxicity.

Background: Multiple factors affect the in vivo antitumor activity of antibody-based therapeutics; however, the influence of cell surface retention on antibody-dependent cellular cytotoxicity (ADCC) is not fully understood. Here we evaluated the importance of cell surface antibody retention in antitumor activity mediated by ADCC in vivo.

Materials And Methods: Two mAbs against tumor-associated calcium signal transducer 2 (TACSTD2/TROP2), AR47A6.

Generation of specific monoclonal antibodies against the extracellular loops of human claudin-3 by immunizing mice with target-expressing cells.

Human claudin-3 (CLDN3) is a tetraspanin transmembrane protein of tight junction structures and is known to be over-expressed in some malignant tumors. Although a specific monoclonal antibody (MAb) against the extracellular domains of CLDN3 would be a valuable tool, generation of such MAbs has been regarded as difficult using traditional hybridoma techniques, because of the conserved sequence homology of CLDN3s among various species. In addition, high sequence similarity is shared among claudin family members, and potential cross-reactivity of MAb should be evaluated carefully.

Pr1E11, a novel anti-TROP-2 antibody isolated by adenovirus-based antibody screening, recognizes a unique epitope.

TROP-2 is a type Ⅰ transmembrane glycoprotein that is highly expressed in various epithelial cancer cells, and its increased expression correlates with poor prognosis. Although several anti-TROP-2 antibodies have been described, they were found unsuitable for antitumor therapy use in vivo as naked antibodies. In this study, we established a novel anti-TROP-2 antibody, designated Pr1E11, from mice immunized with primary prostate cancer cells.

Therapeutic activity of glycoengineered anti-GM2 antibodies against malignant pleural mesothelioma.

Malignant pleural mesothelioma (MPM) is a rare and highly aggressive neoplasm that arises from the pleural, pericardial, or peritoneal lining. Although surgery, chemotherapy, radiotherapy, and combinations of these therapies are used to treat MPM, the median survival of such patients is dismal. Therefore, there is a compelling need to develop novel therapeutics with different modes of action.

The therapeutic potential of a novel PSMA antibody and its IL-2 conjugate in prostate cancer.

Prostate-specific membrane antigen (PSMA) is an attractive target for treatment of prostate cancer. Using the PSMA-recognizing mouse monoclonal antibody 2C9 obtained in our previous study, the biological activities of PSMA antibody were evaluated. Mouse-human chimeric IgG1 of 2C9 (KM2777) showed antibody-dependent cellular cytotoxicity activity against PSMA-expressing prostate cancer cells in the presence of human peripheral blood mononuclear cells (PBMCs).

Characterization and evaluation of the antitumour activity of a dual-targeting monoclonal antibody against claudin-3 and claudin-4.

Background: Because human claudin-3 and claudin-4 (CLDN3 and CLDN4) are overexpressed in a variety of carcinomas, they are promising targets for cancer therapy. The aim of the present study was to generate a dual-targeting monoclonal antibody against CLDN3 and CLDN4 and evaluate its antitumour activity.

Materials And Methods: BALB/c mice were immunised with CLDN4-expressing Chinese hamster ovary cells and cell-based screening was performed.

Novel anti-Tn single-chain Fv-Fc fusion proteins derived from immunized phage library and antibody Fc domain.

Tn[GalNAc(α1-3)-Ser/Thr] antigen, a tumor-associated carbohydrate antigen, is highly expressed in various tumors and an attractive candidate for cancer immunotherapy. The generation of an anti-Tn antibody is a first step toward the construction of new anticancer molecules. However, because of the simple and small conformation of the Tn molecule, it is difficult to generate an anti-Tn antibody for therapeutic use by conventional hybridoma technology.

Establishment of a novel monoclonal antibody against LGR5.

LGR5 is an orphan G-protein-coupled receptor (GPCR) that is expressed on the cell surface membrane. LGR5 is reported to be overexpressed in colon, liver, and ovary tumor compared to normal tissue. However, a specific ligand for LGR5 has not yet been determined, and the function is still not clear.

Therapeutic antitumor efficacy of monoclonal antibody against Claudin-4 for pancreatic and ovarian cancers.

Claudin-4 (CLDN4) is a tetraspanin transmembrane protein of tight junction structure and is highly expressed in pancreatic and ovarian cancers. In this study, we aimed to generate an anti-Claudin-4 monoclonal antibody (mAb) and evaluate its antitumor efficacy in vitro and in vivo. To isolate specific mAb, we generated CLDN3, 4, 5, 6, and 9, expressing Chinese hamster ovary (CHO) cells, and then used them as positive and negative targets through cell-based screening.

Establishment of humanized anti-interleukin-5 receptor alpha chain monoclonal antibodies having a potent neutralizing activity.

Human interleukin-5 is the key cytokine involved in regulating the production and function of human eosinophils. IL-5 binds to its specific receptor composed of two heterogeneous alpha and beta polypeptide chains (hIL-5Ralpha and betac) that are expressed on the cell surface. The hIL-5Ralpha specifically binds IL-5 without involvement of the betac.

Enhanced binding affinity for FcgammaRIIIa of fucose-negative antibody is sufficient to induce maximal antibody-dependent cellular cytotoxicity.

Antibody-dependent cellular cytotoxicity (ADCC) is considered to be an important therapeutic function for clinical efficacy of monoclonal antibodies. Recent studies have revealed two methods to increase binding affinity for FcgammaRIIIa and enhance ADCC more efficiently for antibodies: (i) fucose removal from antibody N-linked complex oligosaccharides and (ii) amino acid mutations in the antibody Fc region. In this study, we compare the biological activities of the methods of generating high ADCC antibodies.

Enhanced Fc-dependent cellular cytotoxicity of Fc fusion proteins derived from TNF receptor II and LFA-3 by fucose removal from Asn-linked oligosaccharides.

Fucose removal from complex-type oligosaccharide of human IgGs results in a major enhancement of Fc-dependent cellular cytotoxicity. The aim of this study was to determine the effect of fucose removal on the effector function of another class of clinically important molecules that can effect cellular cytotoxicity, Fc fusion proteins. The receptors chosen for study were TNF receptor II and LFA-3, both of which have therapeutic significance.

Blockade of paracrine supply of insulin-like growth factors using neutralizing antibodies suppresses the liver metastasis of human colorectal cancers.

Environmental stimuli, such as organ-specific growth factors, can influence the metastatic potential of a tumor. The liver is the main source of insulin-like growth factors (IGFs). The importance of IGF signal in hepatic metastasis has been clarified mainly by IGF-I receptor targeting strategies.

Enhanced natural killer cell binding and activation by low-fucose IgG1 antibody results in potent antibody-dependent cellular cytotoxicity induction at lower antigen density.

Purpose: Recent studies have revealed that fucose removal from the oligosaccharides of human IgG1 antibodies results in a significant enhancement of antibody-dependent cellular cytotoxicity (ADCC) via improved IgG1 binding to FcgammaRIIIa. In this report, we investigated the relationship between enhanced ADCC and antigen density on target cells using IgG1 antibodies with reduced fucose.

Experimental Design: Using EL4 cell-derived transfectants with differential expression levels of exogenous human CC chemokine receptor 4 or human CD20 as target cells, ADCC of fucose variants of chimeric IgG1 antibodies specific for these antigens were measured.

Growth inhibition of human prostate cancer cells in human adult bone implanted into nonobese diabetic/severe combined immunodeficient mice by a ligand-specific antibody to human insulin-like growth factors.

Advanced prostate cancer frequently involves the bone that has the largest content of insulin-like growth factors (IGFs). However, the role of bone-derived IGFs in bone metastasis of prostate cancer has not been studied extensively because of the lack of a reliable animal model. Therefore, we investigated whether a novel antibody directed against human IGF-I and IGF-II (KM1468) could inhibit the development of new bone tumors and the progression of established bone tumors in nonobese diabetic/severe combined immunodeficient mice implanted with human adult bone.

Fucose depletion from human IgG1 oligosaccharide enhances binding enthalpy and association rate between IgG1 and FcgammaRIIIa.

Depletion of fucose from human IgG1 oligosaccharide improves its affinity for Fcgamma receptor IIIa (FcgammaRIIIa). This is the first case where a glycoform modification is shown to improve glycoprotein affinity for the receptors without carbohydrate-binding capacity, suggesting a novel glyco-engineering strategy to improve ligand-receptor binding. To address the mechanisms of affinity improvement by the fucose depletion, we used isothermal titration calorimetry (ITC) and biosensor analysis with surface plasmon resonance.

Defucosylated chimeric anti-CC chemokine receptor 4 IgG1 with enhanced antibody-dependent cellular cytotoxicity shows potent therapeutic activity to T-cell leukemia and lymphoma.

Human IgG1 antibodies with low fucose contents in their asparagine-linked oligosaccharides have been shown recently to exhibit potent antibody-dependent cellular cytotoxicity (ADCC) in vitro. To additionally investigate the efficacy of the human IgG1 with enhanced ADCC, we generated the defucosylated chimeric anti-CC chemokine receptor 4 (CCR4) IgG1 antibody KM2760. KM2760 exhibited much higher ADCC using human peripheral blood mononuclear cells (PBMCs) as effector cells compared with the highly fucosylated, but otherwise identical IgG1, KM3060.

Further investigation of the epitope recognized by the new monoclonal antibody 2C9.

Objective: We established a new monoclonal antibody (2C9) that reacted with prostate tissue. The immunohistochemical reactivity of this antibody is similar to anti-prostate-specific membrane antigen (PSMA). Herein, we report the antigenic determinant of 2C9 antibody.

The absence of fucose but not the presence of galactose or bisecting N-acetylglucosamine of human IgG1 complex-type oligosaccharides shows the critical role of enhancing antibody-dependent cellular cytotoxicity.

An anti-human interleukin 5 receptor (hIL-5R) humanized immunoglobulin G1 (IgG1) and an anti-CD20 chimeric IgG1 produced by rat hybridoma YB2/0 cell lines showed more than 50-fold higher antibody-dependent cellular cytotoxicity (ADCC) using purified human peripheral blood mononuclear cells as effector than those produced by Chinese hamster ovary (CHO) cell lines. Monosaccharide composition and oligosaccharide profiling analysis showed that low fucose (Fuc) content of complex-type oligosaccharides was characteristic in YB2/0-produced IgG1s compared with high Fuc content of CHO-produced IgG1s. YB2/0-produced anti-hIL-5R IgG1 was subjected to Lens culinaris aggulutin affinity column and fractionated based on the contents of Fuc.