title: Depletion of B cells in vivo by a chimeric mouse human monoclonal antibody to CD20.
abstract: Murine monoclonal antibody 2B8 specifically recognizes the CD20 phosphoprotein expressed on the surface of normal B lymphocytes and B-cell lymphomas. The light- and heavy-chain variable regions of 2B8 were cloned, after amplification by the polymerase chain reaction, into a cDNA expression vector that contained human IgG1 heavy chain and human kappa-light chain constant regions. High-level expression of chimeric-2B8 antibody (C2B8) was obtained in Chinese hamster ovary cells. Purified C2B8 exhibited antigen binding affinity and human-tissue reactivity similar to the native murine antibody. In vitro studies showed the ability of C2B8 to bind human C1q, mediate complement-dependent cell lysis of human B-lymphoid cell lines, and lyse human target cells through antibody-dependent cellular cytotoxicity. Infusion of macaque cynomolgus monkeys with doses ranging from 1.6 mg/kg to 6.4 mg/kg resulted in greater than 98% depletion of peripheral blood (PB) B cells and 40% to 70% depletion of lymph node B cells. Recovery of PB B cells usually started at 2 weeks after treatment and required 60 to greater than 90 days to reach normal levels. As much as 95% depletion of B cells in peripheral lymph nodes and bone marrow was observed following weekly injections of 16.8 mg/kg antibody. No toxicity was observed in any of the animals. These results offer the possibility of using an "immunologically active" chimeric anti-CD20 antibody as an alternative approach in the treatment of B-cell lymphoma.
authors.affiliation: IDEC Pharmaceuticals Corporation, San Diego, CA 92121.
authors.forename: M E
authors.initials: ME
authors.lastname: Reff
authors.forename: K
authors.initials: K
authors.lastname: Carner
authors.forename: K S
authors.initials: KS
authors.lastname: Chambers
authors.forename: P C
authors.initials: PC
authors.lastname: Chinn
authors.forename: J E
authors.initials: JE
authors.lastname: Leonard
authors.forename: R
authors.initials: R
authors.lastname: Raab
authors.forename: R A
authors.initials: RA
authors.lastname: Newman
authors.forename: N
authors.initials: N
authors.lastname: Hanna
authors.forename: D R
authors.initials: DR
authors.lastname: Anderson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000627:therapeutic use; D000918:Antibody Specificity; D015703:Antigens, CD / Q000276:immunology*; D018951:Antigens, CD20; D000944:Antigens, Differentiation, B-Lymphocyte / Q000276:immunology*; D001402:B-Lymphocytes / Q000502:physiology*; D001483:Base Sequence; D016466:CHO Cells; D006224:Cricetinae; D006801:Humans; D008198:Lymph Nodes / Q000166:cytology; D008212:Lymphocyte Depletion; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D018951:Antigens, CD20; D000944:Antigens, Differentiation, B-Lymphocyte; D011993:Recombinant Fusion Proteins