James S Bourdage

Eli Lilly, Indianapolis, Indiana, United States

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Publications (7)20.54 Total impact

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    ABSTRACT: Drotrecogin alpha (activated) (DAA) is a recombinant human activated protein C (APC), which is an antithrombotic protein. Objectives: To evaluate the development of anti-APC antibodies in severe sepsis patients in DAA clinical studies. Serum and plasma samples were collected in placebo-controlled studies (PROWESS, ADDRESS) and studies where all patients were DAA-treated (ENHANCE, XPRESS). An enzyme-linked immunosorbent assay detecting anti-APC IgA/IgG/IgM antibodies was used. IgG isolated from plasma of positive samples was tested for neutralizing activity against DAA-induced prolongation of activated partial thromboplastin time. The proportions of patients with negative baseline but positive postbaseline anti-APC antibodies were 1.5% (27/1855) and 1.6% (24/1493) in the DAA and placebo cohorts, respectively (P = 0.72 for the difference). Of the 27 DAA and 24 placebo patients with positive anti-APC antibodies, all but one (DAA) were alive at day 28, and all but seven (four DAA and three placebo) were alive at hospital discharge, including eight (five DAA and three placebo) patients who tested positive for anti-APC neutralizing antibodies. Two of the 51 patients who tested positive for the development of anti-APC antibodies experienced a thrombotic event (one DAA, one placebo). In ADDRESS, no anti-APC antibody was detected in the six DAA-treated patients who had received a previous course of DAA therapy. The proportion of patients with anti-APC antibodies was low and was similar between DAA-treated and placebo-treated patients. No relationship between anti-APC antibody development and adverse reactions was observed. There was no evidence that the anti-APC antibodies detected represented a specific immune response to DAA therapy.
    Journal of Thrombosis and Haemostasis 11/2009; 7(11):1787-94. DOI:10.1111/j.1538-7836.2009.03601.x · 5.55 Impact Factor
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    ABSTRACT: The aim of the study was to determine the extent to which plasma matrix types, diurnal rhythm and sample collection and processing procedures contribute to overall variability of measurements with the INNO-BIA plasma Abeta forms assay. Plasma samples from healthy volunteers were collected at BARC-CRI. Analyte concentrations from various plasma matrix types (EDTA, heparin, fluoride) were compared to serum after collection of blood in commercial plastic and glass tubes. Sample processing variables including time and temperature before and after centrifugation, centrifugal force and plasma dilution factor were also investigated. Diurnal variability in plasma Abeta isoforms was determined in 29 healthy volunteers by analysis of EDTA plasma specimens serially collected over 24 hours and stored frozen following oral administration of a placebo treatment. All plasma samples from a given individual and experiment were analyzed in a single analytical run. Highest Abeta levels were obtained using EDTA-plasma samples (in contrast to serum, heparin, citrate, or fluoride). Addition of aprotinin to EDTA plasma had no effect on Abeta peptide recovery. The elapsed time and temperature exposure, before and after sample processing affects the recovery of Abeta isoforms. Analyte recovery was not significantly affected by the presence of platelets in plasma samples. At the subject level, analysis of serially collected EDTA plasma specimens from healthy volunteers revealed no evidence of diurnal variation in any of the Abeta isoforms investigated and results from samples collected on a monthly basis showed only very limited intra-individual variation. Optimal recovery of Abeta peptides was obtained from blood drawn into EDTA tubes and processed within 4 h. Plasma that was refrigerated after separation and analysed within 4 h gave comparable results to samples immediately processed and frozen at -70 degrees C.
    The Journal of Nutrition Health and Aging 04/2009; 13(3):220-5. · 2.66 Impact Factor
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    ABSTRACT: Objective The aim of the study was to determine the extent to which plasma matrix types, diurnal rhythm and sample collection and processing procedures contribute to overall variability of measurements with the INNO-BIA plasma Aβ forms assay. Methods Plasma samples from healthy volunteers were collected at BARC-CRI. Analyte concentrations from various plasma matrix types (EDTA, heparin, fluoride) were compared to serum after collection of blood in commercial plastic and glass tubes. Sample processing variables including time and temperature before and after centrifugation, centrifugal force and plasma dilution factor were also investigated. Diurnal variability in plasma Aβ isoforms was determined in 29 healthy volunteers by analysis of EDTA plasma specimens serially collected over 24 hours and stored frozen following oral administration of a placebo treatment. All plasma samples from a given individual and experiment were analyzed in a single analytical run. Results Highest Aβ levels were obtained using EDTA-plasma samples (in contrast to serum, heparin, citrate, or fluoride). Addition of aprotinin to EDTA plasma had no effect on Aβ peptide recovery. The elapsed time and temperature exposure, before and after sample processing affects the recovery of Aβ isoforms. Analyte recovery was not significantly affected by the presence of platelets in plasma samples. At the subject level, analysis of serially collected EDTA plasma specimens from healthy volunteers revealed no evidence of diurnal variation in any of the Aβ isoforms investigated and results from samples collected on a monthly basis showed only very limited intra-individual variation. Conclusions Optimal recovery of Aβ peptides was obtained from blood drawn into EDTA tubes and processed within 4 h. Plasma that was refrigerated after separation and analysed within 4 h gave comparable results to samples immediately processed and frozen at −70 °C.
    The Journal of Nutrition Health and Aging 03/2009; 13(3):220-225. DOI:10.1007/s12603-009-0062-5 · 2.66 Impact Factor
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    ABSTRACT: Therapeutic monoclonal antibodies (MoAb) have become important tools in the treatment of numerous diseases. Many of these MoAb are present in the blood at very high levels due to high dosing and long half-lives. Quantification of biomarkers bound by these therapeutic MoAb can be an important factor in determining efficacy and dosing requirements. However, quantitation of these biomarkers with reasonable accuracy can be very difficult to accomplish due to concomitant binding of the therapeutic MoAb. We describe here a novel method for quantifying total (free plus bound) biomarker concentration in the presence of high levels of therapeutic MoAb using a single non-competing MoAb in a capture/elution format. This assay has the capability to accurately detect and quantitate circulating ng/ml biomarker levels in the presence of 200 microg/ml or more of therapeutic MoAb.
    Journal of Pharmaceutical and Biomedical Analysis 08/2008; 48(3):897-901. DOI:10.1016/j.jpba.2008.07.012 · 2.83 Impact Factor
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    ABSTRACT: Monoclonal antibody therapeutics typically have relatively long half-lives and can be dosed at high levels. Although formation of anti-drug antibodies (ADA) is relatively rare, detection of these antibodies can be very difficult in the presence of high circulating levels of drug. Typically these ADA are detected by bridging ELISAs which can be very sensitive to even low levels of drug. We describe an ELISA method based on affinity capture of ADA on solid-phase drug followed by removal of excess free drug, release and transfer of bound ADA and subsequent detection using biotinylated drug. The assay is both sensitive and highly tolerant to free drug with detection of 500 ng/ml of ADA readily achieved in the presence of 500 mug/ml of drug.
    Journal of Immunological Methods 11/2007; 327(1-2):10-7. DOI:10.1016/j.jim.2007.07.004 · 2.01 Impact Factor
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    ABSTRACT: The double antigen bridging immunoassay has been used extensively for detection of immunogenicity responses to therapeutic monoclonal antibodies. We have analyzed parameters affecting performance of this type of immunoassay including microtiter plate antigen coating concentration, enzyme-labeled antigen conjugate dilution and assay format (one-step versus two-step). We present results demonstrating that the format of the assay has a significant impact on the optimal parameters to maximize assay performance. A one-step assay format achieves maximal sensitivity across a broad range of coating concentrations and at a lower concentration of conjugate than that in a two-step format. In contrast, a two-step format requires very low coating concentrations and higher conjugate concentrations to achieve maximal sensitivity and suffers from significantly reduced sensitivity at higher coating concentrations. Together, these findings indicate that a one-step assay format can greatly reduce the effect of coating concentration variation on assay performance.
    Journal of Pharmaceutical and Biomedical Analysis 10/2005; 39(3-4):685-90. DOI:10.1016/j.jpba.2005.03.037 · 2.83 Impact Factor
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    ABSTRACT: Development of immunogenicity assays for assessment of human antibodies to therapeutic proteins requires a quantitative determination of assay sensitivity. In the absence of true human positive controls, this is usually accomplished by utilizing affinity-purified antibodies from non-human primates or monoclonal antibodies. In the former case, it is generally considered that non-human primate antibodies will be recognized equally to human antibodies by secondary anti-human immunoglobulin reagents used in immunogenicity assays. We present results here demonstrating that this is not the case. In reality, anti-human immunoglobulin secondary antibodies do not recognize primate immunoglobulins as well as human immunoglobulins. As a result, the use of affinity purified primate antibodies to determine the sensitivity of an immunogenicity assay will likely result in the true sensitivity of the assay being underestimated.
    Journal of Immunological Methods 09/2005; 303(1-2):76-80. DOI:10.1016/j.jim.2005.06.003 · 2.01 Impact Factor