title: Immunogenicity of granulocyte-macrophage colony-stimulating factor (GM-CSF) products in patients undergoing combination therapy with GM-CSF.
abstract: In this study, we have assessed the development of neutralizing and nonneutralizing granulocyte-macrophage colony-stimulating factor (GM-CSF) antibodies in two groups of patients with metastatic colorectal carcinoma receiving two different GM-CSF products. Three clinical trials were carried out, and a combination of GM-CSF and a colon carcinoma-reactive antibody was used in the absence of any concomitant chemotherapy. Two different GM-CSF products, both rDNA-derived and produced in Escherichia coli, were used. Patients in Trial 1 received product X, and those in Trials 2 and 3 received product Y. Patients in Trial 2 also received interleukin 2 in an attempt to potentiate immune responses. After the first cycle of treatment, no GM-CSF antibodies were detected, but on subsequent therapy, 28 of the 38 patients tested receiving product Y (Trials 2 and 3) developed antibodies that bound to the GM-CSF product used for therapy. However, none of the patients developed antibodies that neutralized the biological activity of GM-CSF, as assessed using an in vitro bioassay. Furthermore, there was no in vivo impairment in GM-CSF-induced expansion of leukocytes, neutrophils, and eosinophils in the patients. In contrast, 19 of the 20 patients given product X (Trial 1) developed GM-CSF binding antibodies, and 9 of these patients were shown to develop antibodies that neutralized the biological activity of GM-CSF. The presence of the latter was associated with a significant reduction in GM-CSF-induced expansion of leukocytes, neutrophils, and eosinophils in patients. Therefore, product X appears to be more immunogenic than product Y. Immunochemical characterization confirmed that the specificity of the antibody responses varied depending on the product used for therapy. Whereas sera from Trial 1 patients treated with product X showed the presence of antibodies with strong recognition of GM-CSF proteins, sera from patients treated with product Y showed varied recognition of GM-CSF ranging from fairly strong to very weak but bound predominantly to two E. coli-derived, non-GM-CSF-related proteins of Mr approximately 20,000 and Mr approximately 30,000. Therefore, in sera from patients receiving product Y, the antibody specificity appeared to be directed not only against GM-CSF but also against non-product-related host cell contaminants. This study shows that GM-CSF products used for therapy are potentially immunogenic and generate antibodies to GM-CSF and/or other non-product-related contaminants. However, only antibodies that neutralize the biological activity of GM-CSF compromise therapeutic efficacy of the cytokine.
authors.affiliation: Division of Immunobiology, National Institute for Biological Standards and Control, Hertfordshire, United Kingdom. mwadhwa@nibsc.ac.uk
authors.forename: M
authors.initials: M
authors.lastname: Wadhwa
authors.forename: A L
authors.initials: AL
authors.lastname: Skog
authors.forename: C
authors.initials: C
authors.lastname: Bird
authors.forename: P
authors.initials: P
authors.lastname: Ragnhammar
authors.forename: M
authors.initials: M
authors.lastname: Lilljefors
authors.forename: R
authors.initials: R
authors.lastname: Gaines-Das
authors.forename: H
authors.initials: H
authors.lastname: Mellstedt
authors.forename: R
authors.initials: R
authors.lastname: Thorpe
mesh_terms: D000328:Adult; D000368:Aged; D000906:Antibodies / Q000097:blood / Q000378:metabolism; D000911:Antibodies, Monoclonal / Q000627:therapeutic use; D000918:Antibody Specificity; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D001667:Binding, Competitive / Q000276:immunology; D015179:Colorectal Neoplasms / Q000628:therapy*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000276:immunology* / Q000627:therapeutic use*; D006801:Humans; D015151:Immunoblotting; D007376:Interleukin-2 / Q000276:immunology / Q000627:therapeutic use; D007958:Leukocyte Count / Q000187:drug effects; D008875:Middle Aged; D011994:Recombinant Proteins
chemical_list: D000906:Antibodies; D000911:Antibodies, Monoclonal; D007376:Interleukin-2; D011994:Recombinant Proteins; D016178:Granulocyte-Macrophage Colony-Stimulating Factor