title: A human CD4 monoclonal antibody for the treatment of T-cell lymphoma combines inhibition of T-cell signaling by a dual mechanism with potent Fc-dependent effector activity.
abstract: Zanolimumab is a human IgG1 antibody against CD4, which is in clinical development for the treatment of cutaneous and nodal T-cell lymphomas. Here, we report on its mechanisms of action. Zanolimumab was found to inhibit CD4+ T cells by combining signaling inhibition with the induction of Fc-dependent effector mechanisms. First, T-cell receptor (TCR) signal transduction is inhibited by zanolimumab through a fast, dual mechanism, which is activated within minutes. Ligation of CD4 by zanolimumab effectively inhibits early TCR signaling events but, interestingly, activates signaling through the CD4-associated tyrosine kinase p56lck. An uncoupling of p56lck from the TCR by anti-CD4 allows the kinase to transmit direct inhibitory signals via the inhibitory adaptor molecules Dok-1 and SHIP-1. Second, CD4+ T cells are killed by induction of antibody-dependent cell-mediated cytotoxicity, to which CD45RO+ cells are more sensitive than CD45RA+ cells. Finally, zanolimumab induces down-modulation of CD4 from cell surfaces via a slow Fc-dependent mechanism. In conclusion, zanolimumab rapidly inhibits T-cell signaling via a dual mechanism of action combined with potent Fc-dependent lysis of CD4+ T cells and may act long-term by down-regulating CD4.
authors.affiliation: Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Cambridge, United Kingdom.
authors.forename: David A
authors.initials: DA
authors.lastname: Rider
authors.forename: Carin E G
authors.initials: CE
authors.lastname: Havenith
authors.forename: Ruby
authors.initials: R
authors.lastname: de Ridder
authors.forename: Janine
authors.initials: J
authors.lastname: Schuurman
authors.forename: Cedric
authors.initials: C
authors.lastname: Favre
authors.forename: Joanne C
authors.initials: JC
authors.lastname: Cooper
authors.forename: Simon
authors.initials: S
authors.lastname: Walker
authors.forename: Ole
authors.initials: O
authors.lastname: Baadsgaard
authors.forename: Susanne
authors.initials: S
authors.lastname: Marschner
authors.forename: Jan G J
authors.initials: JG
authors.lastname: vandeWinkel
authors.forename: John
authors.initials: J
authors.lastname: Cambier
authors.forename: Paul W H I
authors.initials: PW
authors.lastname: Parren
authors.forename: Denis R
authors.initials: DR
authors.lastname: Alexander
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology* / Q000627:therapeutic use; D061067:Antibodies, Monoclonal, Humanized; D000920:Antibody-Dependent Cell Cytotoxicity; D017252:CD3 Complex / Q000276:immunology; D015704:CD4 Antigens / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology; D018791:CD4 Lymphocyte Count; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects* / Q000276:immunology; D004311:Double-Blind Method; D015536:Down-Regulation; D006801:Humans; D000072181:Inositol Polyphosphate 5-Phosphatases; D008213:Lymphocyte Activation / Q000187:drug effects; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000378:metabolism; D016410:Lymphoma, T-Cell, Cutaneous / Q000276:immunology* / Q000628:therapy*; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D010766:Phosphorylation; D011565:Psoriasis / Q000276:immunology / Q000628:therapy; D011948:Receptors, Antigen, T-Cell / Q000276:immunology / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D017252:CD3 Complex; D015704:CD4 Antigens; D011948:Receptors, Antigen, T-Cell; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D010744:Phosphoric Monoester Hydrolases; D000072181:Inositol Polyphosphate 5-Phosphatases; C000606430:INPP5D protein, human; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases; C520522:zanolimumab