title: Unexpected cross-reactivity of anti-cathepsin B antibodies leads to uncertainties regarding the mechanism of action of anti-CD20 monoclonal antibody GA101.
abstract: GA101, also known as obinutuzumab or Gazyva (Gazyvaro), is a glycoengineered type II humanized antibody that targets the CD20 antigen expressed at the surface of B-cells. This novel anti-CD20 antibody is currently assessed in clinical trials with promising results as a single agent or as part of therapeutic combinations for the treatment of B-cell malignancies. Detailed understanding of the mechanisms of GA101-induced cell death is needed to get insight into possible resistance mechanisms occurring in patients. Although multiple in vitro and in vivo mechanisms have been suggested to describe the effects of GA101 on B-cells, currently available data are ambiguous. The aim of our study was to clarify the cellular mechanisms involved in GA101-induced cell death in vitro, and more particularly the respective roles played by lysosomal and mitochondrial membrane permeabilization. Our results confirm previous reports suggesting that GA101 triggers homotypic adhesion and caspase-independent cell death, two processes that are dependent on actin remodeling and involve the production of reactive oxygen species. With respect to lysosomal membrane permeabilization (LMP), our data suggest that lack of specificity of available antibodies directed against cathepsin B may have confounded previously published results, possibly challenging current LMP-driven model of GA101 action mode.
authors.affiliation: Molecular Biology of the Cell Laboratory, Ecole Normale Supérieure de Lyon, UMR 5239 CNRS-UCBL-ENS Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France.
authors.forename: Wei Wen
authors.initials: WW
authors.lastname: Chien
authors.affiliation: Molecular Biology of the Cell Laboratory, Ecole Normale Supérieure de Lyon, UMR 5239 CNRS-UCBL-ENS Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France.
authors.forename: Charlène
authors.initials: C
authors.lastname: Niogret
authors.affiliation: Molecular Biology of the Cell Laboratory, Ecole Normale Supérieure de Lyon, UMR 5239 CNRS-UCBL-ENS Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France.
authors.forename: Romain
authors.initials: R
authors.lastname: Jugé
authors.affiliation: Molecular Biology of the Cell Laboratory, Ecole Normale Supérieure de Lyon, UMR 5239 CNRS-UCBL-ENS Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France.
authors.forename: Loïc
authors.initials: L
authors.lastname: Lionnard
authors.affiliation: Molecular Biology of the Cell Laboratory, Ecole Normale Supérieure de Lyon, UMR 5239 CNRS-UCBL-ENS Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France.
authors.forename: Aurélie
authors.initials: A
authors.lastname: Cornut-Thibaut
authors.affiliation: Molecular Biology of the Cell Laboratory, Ecole Normale Supérieure de Lyon, UMR 5239 CNRS-UCBL-ENS Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Kucharczak
authors.affiliation: Institut Roche, 30, Cours de l'Ile Seguin, 92650 Boulogne-Billancourt Cedex, France. Electronic address: ariel.savina@roche.com.
authors.forename: Ariel
authors.initials: A
authors.lastname: Savina
authors.affiliation: Molecular Biology of the Cell Laboratory, Ecole Normale Supérieure de Lyon, UMR 5239 CNRS-UCBL-ENS Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France; Hospices Civils de Lyon, Service d'Hématologie, 165 Chemin du Grand Revoyet, 69495, Pierre-Bénite, France. Electronic address: Gilles.Salles@chu-lyon.fr.
authors.forename: Gilles
authors.initials: G
authors.lastname: Salles
authors.affiliation: Molecular Biology of the Cell Laboratory, Ecole Normale Supérieure de Lyon, UMR 5239 CNRS-UCBL-ENS Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France; ISEM-Institut des Sciences de l'Evolution de Montpellier, UMR 5554, University of Montpellier, CNRS, IRD, CIRAD, EPHE, Place Eugène Bataillon, 34095 Montpellier, France. Electronic address: abdel.aouacheria@umontpellier.fr.
authors.forename: Abdel
authors.initials: A
authors.lastname: Aouacheria
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized / Q000493:pharmacokinetics / Q000627:therapeutic use*; D018951:Antigens, CD20 / Q000276:immunology; D002401:Cathepsin B / Q000276:immunology*; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D003429:Cross Reactions / Q000276:immunology*; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism; D015448:Leukemia, B-Cell / Q000188:drug therapy; D008247:Lysosomes / Q000648:ultrastructure; D051336:Mitochondrial Membranes / Q000378:metabolism; D010539:Permeability / Q000187:drug effects
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D018951:Antigens, CD20; D002401:Cathepsin B; C543332:obinutuzumab
keywords: Antibody-based immunotherapy; CD20; Cathepsin B; Cell death; GA101; Lymphomas; Lysosomal permeabilization