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Title: In vitro and in vivo antitumor activity of a chimeric anti-CD19 antibody.
Austin Authors: Pietersz, Geoffrey A;Wenjun, L;Sutton, V R;Burgess, John R;McKenzie, Ian F C;Zola, H;Trapani, Joseph A
Affiliation: Austin Research Institute, Austin Hospital, Heidelberg, Victoria, Australia
Issue Date: 1-Jul-1995
Publication information: Cancer Immunology, Immunotherapy : Cii; 41(1): 53-60
Abstract: Mouse monoclonal antibodies to CD19 detect an antigenic determinant expressed exclusively on the surface of B lymphocytes, and have previously been shown to be potentially useful therapeutic reagents for human B cell lymphoma. We report the production and characterization of a mouse/human chimeric antibody, cCD19, with potent in vivo antitumour activity. The genes encoding the variable domains for heavy (VH) and light (VL) chains were subcloned into eukaryotic expression vectors containing human constant region genes (IgG1 and kappa), and co-transfected into non-secreting Sp2/0 mouse myeloma cells. Intraperitoneal administration of cCD19 produced inhibition of growth of subcutaneous CD19+ Sultan human B lymphoma tumours in scid/scid mice. When the antibody was administered 18 and 20 days after subcutaneous tumour inoculation, an approximately 30% reduction in tumour size was noted by day 29. cCD19 faithfully mimicked the in vitro binding characteristics of mCD19 as (a) the chimeric antibody was shown by flow cytometry to bind exclusively to cell lines that expressed CD19, (b) cCD19 was able to inhibit the binding of mCD19 on CD19+ cells completely and (c) the affinity of binding of the two antibodies was not significantly different [Ka = (2.03 +/- 1.5) x 10(8)]. In bio-distribution studies, up to 14.8% of the total injected antibody dose per gram of tissue was localized in CD19+ Sultan tumours at 24 h approximately, 14.4% was present in the tumors at 48 h, and about 13.7% at 72 h. These levels were comparable to mCD19 administered in the same fashion. cCD19 conjugated to idarubicin was specifically and strongly cytotoxic to CD19+ cells cultured in vitro, and demonstrated an IC50 of 0.17 microM, similar to that of mCD19 (0.32 microM) and approximately 14-fold greater than the IC50 of free idarubicin. The specific cytotoxic capacity of cCD19 and its likely reduced immunogenicity suggest that it may potentially be of use in the treatment of refractory B cell lymphoma in humans.
Gov't Doc #: 7543822
Journal: Cancer immunology, immunotherapy : CII
Type: Journal Article
Subjects: Animals
Antibodies, Monoclonal.immunology
Antigen-Antibody Reactions
Antigens, CD.immunology
Antigens, CD19
Antigens, Differentiation, B-Lymphocyte.immunology
Idarubicin.administration & dosage
Immunity, Cellular
Immunoconjugates.administration & dosage
Mice, SCID
Recombinant Fusion Proteins
Tumor Cells, Cultured.immunology
Appears in Collections:Journal articles

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