Human Antibodies - Volume 19, issue 4

Authors: Mohammadnejad, J. | Rasaee, M.J. | Babaei, M.H. | Paknejad, M. | Zahir, M.H. | Salouti, M. | Rajabi, A. Bitarafan | Mazidi, M.

Article Type: Research Article

Abstract: PR81 is a monoclonal antibody that binds with high affinity to MUC1, which is over expressed on breast and other tumors. The objective of this study was to evaluate the application of this antibody against MUC1 as a radioimmunotherapeutical agent. Monoclonal antibody (PR81) against MUC1 was prepared, characterized, purified, and labeled with 131 I. The immunoreactivity of radiolabeled mAb PR81with MUC1 (the native protein), BSA-P20 (a 20 amino acid corresponding the tandem repeat of MUC1) and MCF7 cell line were performed by RIA. In vitro stability of radiolabeled mAb in human serum was determined by thin layer chromatography (TLC). Cell …toxicity and in vitro internalization studies were performed with the MCF7 cell line, and the tissue biodistribution of the radioiodinated PR81 was evaluated in normal BALB/c mice at 4, 24 and 48 hrs. The tumor imaging was performed in BALB/c mice with breast xenograft tumors at 24 and 72 hr after the complex injection. The labeling efficiency was found to be 59.9% ± 7.9%. MAb- 131 I conjugates showed high immunoreactivity towards MUC1 protein, BSA-P20 and MCF7 cell line. In vitro stability of the labeled product in human serum was found to be more than %50 over 24 hr. Cell toxicity and in vitro internalization studies showed that the mAb-131 I conjugate inhibited 80% growth of the MCF7 cultured cell lines in vitro in a high concentration and up to %60 of the conjugate internalized after 24 h. Biodistribution studies were performed in normal BALB/c mice at 4, 24 and 48 hrs post-injection and no important accumulation was observed in vital organs. The tumors were visualized with high sensitivity after 24 and 72 hr in radioimmunoscintographical studies. These results show that the new radiopharmaceutical may be considered as a promising candidate for therapy of breast cancer. Show more

Keywords: Radioiodination, monoclonal antibody PR81, MUC1, radioimmunotherapy

DOI: 10.3233/HAB-2010-0231

Citation: Human Antibodies, vol. 19, no. 4, pp. 79-88, 2010

Authors: Patel, Dipa | Guo, Xuemei | Ng, Stanley | Melchior, Maxine | Balderes, Paul | Burtrum, Douglas | Persaud, Kris | Luna, Xenia | Ludwig, Dale L. | Kang, Xiaoqiang

Article Type: Research Article

Abstract: Purpose: To evaluate the antibody-dependent cellular cytotoxicity (ADCC) of cetuximab, an anti-epidermal growth factor receptor (EGFR) IgG1 antibody, in vitro. Methods: Binding to human Fc receptors was measured by ELISA. ADCC against a panel of tumor cell lines was evaluated using peripheral blood mononuclear cells or NK cells as effectors and lactate dehydrogenase release as a marker of cell killing. Cetuximab was compared with two glycan variants of cetuximab and with panitumumab, an anti-EGFR IgG2 . Results: Cetuximab bound with high affinity to FcγRI (EC50 = 0.13 nM) and FcγRIIIa (EC50 = 6 …nM) and effectively induced ADCC across multiple tumor cell lines. Panitumumab and aglycosylated cetuximab did not bind to FcγRI or FcγRIIIa nor have ADCC activity even at high effector-target cell ratios, even though the EGFR-binding affinity of cetuximab and panitumumab were shown to be comparable (KD = 87 pM and 83 pM, respectively). The extent of cetuximab-elicited ADCC was associated with the level of EGFR expression on tumor cells. Conclusions: Cetuximab elicits effective ADCC activity against a wide range of tumor cells in vitro. This activity is dependent on antibody glycosylation and IgG1 isotype as well as tumor-cell EGFR expression. These findings suggest that ADCC may contribute to the antitumor activity of cetuximab. Show more

Keywords: Epidermal growth factor receptor, antibody-dependent cellular cytotoxicity, monoclonal antibody, cetuximab, panitumumab

DOI: 10.3233/HAB-2010-0232

Citation: Human Antibodies, vol. 19, no. 4, pp. 89-99, 2010

Authors: Shinmoto, Hiroshi | Takeda, Mio | Matsuo, Yuji | Naganawa, Yasunori | Tomita, Shinichi | Takano-Ishikawa, Yuko

Article Type: Research Article

Abstract: A human-mouse hybridoma clone #86 secreting IgM-class human monoclonal antibody to peanut allergen protein Ara h1 was newly established. To detect an antibody-binding sequence (epitope) on Ara h1, the monoclonal antibody #86 was reacted with multi-pin apparatus with a series of peptides synthesized from the amino acid sequence of Ara h1. The antibody #86 was found to bind to a peptide with amino acid sequence of 481EEEEDEDEEEEGSNREVRRY500. Further analysis with shorter pin-peptides with ten amino acid-long showed that the peptides reacted with the antibody #86 contained a sequence of 485DEDEEEE491. This might be an essential linear sequence of this epitope. …When the 485DED487 part of the peptide was replaced by alanine, decreased binding of antibody #86 was observed. Show more

Keywords: Human monoclonal antibody, allergen, peanut, epitope, IgM

DOI: 10.3233/HAB-2010-0233

Citation: Human Antibodies, vol. 19, no. 4, pp. 101-105, 2010

Authors: Hosseinimehr, Seyed Jalal | Orlova, Anna | Tolmachev, Vladimir

Article Type: Research Article

Abstract: Bevacizumab is a humanized monoclonal antibody that binds to vascular endothelial growth factor (VEGF) and prevents tumor angiogenesis. Radionuclide imaging using radiolabeled bevacizumab might be useful for selection of patients for anti-VEGF therapy. This study describes preparation of a potential imaging agent, 111 In-CHX-A"-DTPA-bevacizumab, and evaluation of specificity of its binding to three tumor cell lines, SKOV3, LS174T and DU 145. Bevacizumab was conjugated with CHX-A"-DTPA and radiolabeled with 111 In with high yield and excellent stability. Specificity of cellular binding was examined by a saturation assay using 100-fold excess of non-radiolabeled antibody. SKOV3 and LS174T tumor cell lines showed …significantly specific binding, while DU 145 cells did not showed any specific binding. The specific binding is dependent to type of cell lines, which it is important for selection of tumor model for scintigraphic imaging of the VEGF expression. Show more

Keywords: Bevacizumab, scintigraphy, avastin, indium, VEGF

DOI: 10.3233/HAB-2010-0234

Citation: Human Antibodies, vol. 19, no. 4, pp. 107-111, 2010

Authors: Ebert, Tim | Smith, Sharon | Pancari, Greg | Clark, Desmond | Hampton, Richard | Secore, Susan | Towne, Victoria | Fan, Hongxia | Wang, Xin-Min | Wu, Xiaoqing | Ernst, Robin | Harvey, Barrett R. | Finnefrock, Adam C. | Wang, Fubao | Tan, Charles | Durr, Eberhard | Cope, Leslie | Anderson, Annaliesa | An, Zhiqiang | McNeely, Tessie

Article Type: Research Article

Abstract: A fully human monoclonal antibody (CS-D7, IgG1 ) specific for the iron regulated surface determinant B (IsdB) of Staphylococcus aureus was isolated from the Cambridge Antibody Technology (CAT) scFv antibody library. As compared to previously described IsdB specific murine monoclonals, CS-D7 has a unique, non-overlapping binding site on IsdB, and exhibits increased in vivo activity. The antibody recognizes a conformational epitope spanning amino acids 50 to 285 and has a binding affinity of 340 (± 75) pM for IsdB. CS-D7 bound to a wide variety of S. aureus strains, but not to an isdB deletion mutant. The antibody mediated opsonophagocytic …(OP) killing in vitro and mediated significant protection in vivo. In a murine lethal sepsis model, the antibody conferred protection from death when dosed prior to challenge, but not when dosed after challenge. Importantly, in a central venous catheter (CVC) model in rats, the antibody reduced bacteremia and prevented colonization of indwelling catheters. Protection was observed when rats were dosed with CS-D7 prior to challenge as well as post challenge. IsdB is currently being investigated for clinical efficacy against S. aureus infection, and the activity of this human IsdB specific antibody supplements the growing body of evidence to support targeting this antigen for vaccine development. Show more

Keywords: Staphylococcus, monoclonal antibody, iron regulated surface determinant, rodent models, indwelling catheter model, biofilm, survival model

DOI: 10.3233/HAB-2010-0235

Citation: Human Antibodies, vol. 19, no. 4, pp. 113-128, 2010