Strategies for the preclinical and clinical characterization of immunogenicity.
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Biomedical subjects
Publications and source records attributed to D Mytych.
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Biosensor instruments, such as the BIACORE, are gaining popularity for analysing serum samples for the presence of antibodies. These instruments offer several advantages in the detection and subsequent characterization of clinically relevant antibodies generated in response to administration of therapeutic proteins. Much like other common immunoassay platforms, immobilized ligand is used to capture antibodies. Unlike conventional approaches, the ligand is immobilized to the surface of a biosensor chip, with detection based upon surface plasmon resonance. This assay platform, therefore, does not require reporter molecules such as enzymes, fluorochromes or radioisotopes that are common to conventional immunoassay methodologies. Additional desirable features of the biosensor platform include real-time detection of the binding of antibody to ligand (for kinetic measurements) as well as straightforward characterization of antibody isotype, specificity and relative concentration. This is all performed with minimum serum requirements (typically 10 microlitres per sample analysed) in a fully automated environment. The unique features of the biosensor instrument warrant that these assays are referred to as biosensor immunoassays to clearly distinguish them from more conventional immunoassay methodologies, such as ELISA.
Biosensor and electrochemiluminescent (ECL) assays are replacing enzyme-linked immunosorbent assays (ELISAs) at Schering-Plough as immunoassays of choice to monitor cytokine levels and detect anti-cytokine antibody responses during cytokine therapy. These new assays provide increased sensitivity and a better correlation with biological assays. Biosensor assays using the BIACORE 2000 (BIACORE, Uppsala, Sweden) are being adopted to support preclinical and clinical trials for the detection of antibodies capable of binding to IL-10 and IL-4. Significant advantages when using a biosensor assay are that real-time and label-free detection permit increased throughput and direct detection of binding interactions which enables detection of low affinity antibodies that are not detected by ELISA. The ECL assays using the ORIGEN Analyser (IGEN, Gaithersburg, MD) that we have implemented to replace existing ELISAs for quantification of serum IL-10 and serum interferon alfa levels are more sensitive and less subject to matrix effects. Data obtained during the validation of these assays are described.
This report documents the validation of an assay using BIAcore 2000 that, with a single injection of mouse serum, allows the quantitation of a humanized monoclonal antibody and can also detect the presence of antibodies directed against this humanized antibody. The important components required for the validation of biosensor assays including precision, accuracy, linearity, stability of the immobilized ligand, specificity and sensitivity are addressed. The tandem assay that is used as a model for biosensor validations is accomplished by flowing each sample across the surface of two flowcells in sequence. The first flowcell has the antigen that the humanized mAb was generated against immobilized while the humanized mAb itself is immobilized on the second flowcell. The quantitation component of this assay is precise and accurate with a limit of quantitation of 1 microg/ml in mouse serum samples. Any antibodies directed against the humanized mAb can be detected and also characterized as to isotype. This unique assay can be performed with as little as 10 microl of serum which is then diluted ten-fold prior to analysis. The small sample requirement allows analysis of individual mouse serum samples rather than requiring the use of pooled samples from multiple mice. A further advantage of this assay is the automation capability which allows unattended operation.