Immunohistochemistry Based Assay Development of Clinical Biomarkers
Malini A Venkata,
Lead Investigator,
Biocon Bristol Myers Squibb
Our immune system plays an important role in fighting cancer. Immuno-oncology therapies which target the body’s immune system, not the tumour itself, enable the immune system to selectively recognize and attack cancer cells, and give long-lasting memory to the immune system, so that it can continually adapt to the cancer over time and provide durable, long-term response to the cancer. However, they do not work in all patients. Characterization of the tumor microenvironment reveals evidence for distinct immunologic phenotypes based on the presence or absence of key effector cells. These observations have generated candidate predictive biomarkers for response to immunotherapies and are guiding the identification of new immunotherapeutic interventions. Immunohistochemistry (IHC) is a core platform for the analysis of tissue samples, and there is an increasing need for robust, reliable and quantitative IHC-based biomarkers in oncology. As “off the shelf reagents” drive most IHC based target validation efforts, validation of the antibody during assay development is essential. Target overexpression on transfected cells, protein competition assays, normal tissue cross reactivity studies, endogenous target knock down are some of the methods that help determine antibody specificity. Understanding the target, selection of appropriate control tissues / cells, method selection and optimization, validation and qualification are salient steps in IHC based assay development. This step wise approach helps built confidence in the antibody and the data generated, eventually enabling the identification of assays that will have clinical impact.
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