Chaoyuan Chen

Purdue Pharma L.P., Stamford, Connecticut, United States

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Publications (4)4.29 Total impact

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    ABSTRACT: Antibodies to CA 125 have been used to predict relapse of ovarian cancer, but have performed poorly as therapeutic agents. One rationale for this is antibody binding to circulating shed antigen. Our aim in this study was to develop antibodies to human CA 125 that have enhanced selectivity for the cell-associated form of the antigen. Monoclonal antibodies were raised to a recombinant fragment of CA 125 that included sequence proximal to the putative membrane attachment site. Antibodies were characterized in terms of their binding site, affinity and selectivity for cell-associated CA 125. In assays using patient-derived CA 125, a subset of high-affinity (KD <5 nM) monoclonal antibodies demonstrated a 10- to greater than 200-fold increase in selectivity for cell-associated CA 125 when compared with controls. Based on mapping of the various monoclonal antibodies obtained, it was determined that shedding of CA 125 most likely occurs in the most C-terminal repeat domain. Results from competition analysis using patient-derived shed antigen predict that the antibodies described in this study may have significantly enhanced tumor-targeting properties when compared with existing antibodies to CA 125 in a tumor environment having high concentrations (>10,000 CA 125 units) of shed CA 125.
    Tumor Biology 05/2006; 27(3):122-32. DOI:10.1159/000092717 · 3.61 Impact Factor
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    ABSTRACT: Fibroblast growth factor receptor 4 (FGFR4) is a member of the FGFR family of receptor tyrosine kinases, and plays important roles in a variety of biological functions such as cell proliferation, differentiation, migration, angiogenesis, tissue repair, and tumorigenesis. The human FGFRs share a high degree of sequence homology between themselves, as well as with their murine homologs. Consequently, it has been suggested that it may be difficult to prepare monoclonal antibodies (MAbs) that are specific for the individual receptor types. In this communication, we report on the development and characterization of a panel of anti-human FGFR4 MAbs that were generated in mice using a rapid immunization protocol. Using a modified rapid immunization at multiple sites (RIMMS) protocol with the soluble extracellular domain of human FGFR4 (FGFR4-ECD), the immunized mice developed high levels of polyclonal IgG to the immunogen within 13 days of the first immunization. The lymph node cells isolated from the immunized animals were then fused with mouse myeloma cells for hybridoma generation. Use of an efficient hybridoma cloning protocol in combination with an ELISA screening procedure allowed for early identification of stable hybridomas secreting antihuman FGFR4 IgG. Several identified MAbs specifically reacted with the FGFR4 protein without binding to the other human isoforms (FGFR1, FGFR2, and FGFR3). As evaluated by BIAcore analysis, most anti-FGFR4 MAbs displayed high affinities (8.6 x 10(8) approximately 3.9 x 10(10) M) to FGFR4. Furthermore, these MAbs were able to bind to FGFR4 expressed on human breast tumor cell lines MDA-MB-361 and MDA-MB-453. Taken together, the results demonstrate that the RIMMS strategy is an effective approach for generating class-switched, high-affinity MAbs in mice to evolutionarily conserved proteins such as human FGFR4. These MAbs may be useful tools for further investigation of the biological functions and pathological roles of human FGFR4.
    Hybridoma (2005) 07/2005; 24(3):152-9. DOI:10.1089/hyb.2005.24.152 · 0.34 Impact Factor
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    ABSTRACT: Tissue factor (TF) plays an important, physiological role in hemostasis. Recent studies have demonstrated the over-expression of TF in a number of solid tumor types and its pathological roles in angiogenesis and tumor metastasis. In this study, we report the development and characterization of a panel of murine MAbs that are specific for human TF, but do not inhibit TF-mediated blood coagulation. By using a modified repetitive immunizations at multiple sites (RIMMS) protocol in conjunction with an efficient hybridoma cloning procedure, anti-TF MAbs were generated within a relatively short time frame of 5-6 weeks. Following primary screening by ELISA, the binding of the MAbs to the native form of human TF was demonstrated in flow cytometry using a stable cell line expressing human TF. Several of these TF-specific MAbs did not inhibit blood coagulation in a blood coagulation assay and bound with high affinity (0.5-2 nM) to human TF in BIAcore analyses. Importantly, this study represents an independent evaluation of the RIMMS strategy for MAb generation and demonstrates that class-switched, high-affinity MAbs can be generated rapidly and reliably using RIMMS.
    Hybridoma (2005) 05/2005; 24(2):78-85. DOI:10.1089/hyb.2005.24.78 · 0.34 Impact Factor
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    ABSTRACT: There is considerable interest in developing immunotherapeutic approaches to elicit tumor-specific CTL responses in cancer patients. Epitope-based approaches aim to deliver the antigenic peptides or epitopes recognized by CTLs rather than the intact tumor antigen. Many tumor-associated proteins are nonmutated self proteins for which the dominant peptide epitopes are usually poorly immunogenic. The subdominant epitopes, however, can elicit robust T cell responses if optimized for their ability to bind to class I MHC molecules. Only the epitopes for a few tumor antigens expressed in human cancers have been defined to this level, mainly for technical reasons. The means to rapidly screen and characterize the binding of epitopes derived from complex tumor-associated antigens is an important enabling technology. Here, we have used the high-throughput technology iTopia to identify those peptides derived from the tumor-associated antigen survivin that bind 8 class I alleles. A library of overlapping nonamers spanning the length of the survivin protein was initially screened for peptides capable of binding each allele. Nineteen HLA-A*0201, zero HLA-A*0101, seven HLA-A*0301, twelve HLA-A*1101, twenty-four HLA-A*2402, six HLA-B*0702, six HLA-B*0801, and eight HLA-B*1501 binding peptides were identified based on an arbitrary cutoff. Peptides capable of binding a given allele were further characterized by their affinity for MHC class I molecules and by the rate of dissociation of the complex. This information should help guide functional studies and future epitope-based immunotherapies.
    Cancer immunity: a journal of the Academy of Cancer Immunology 02/2005; 5:6.