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Table 2 Comparison of bioanalytical assays with immune response-based assays

From: Validation of biomarkers to predict response to immunotherapy in cancer: Volume I — pre-analytical and analytical validation

Characteristics Bio-analytical Assays Immune-based Assays
Number of analytes Single analyte relative to biological functions (small molecules or macromolecules) Multiple analytes with complex functional relationships between tumor and immune system
Category of measurement Absolute quantitation Quasi-quantitative, relative-quantitative or qualitative. Qantification is available for specific assays
Reference material Available Not available, limited availability or available - depends on the assay
Linearity of analyte(s) Known Unknown or do not demonstrate linearity, often unknown dynamic ranges, or dynamic range can be established-depends on the assay
Limit of detection (LOD) Available Not quantifiable or LOD available - depends on the assay
Sample processing Extraction required for small molecules; Direct measurement in biological matrix without sample pretreatment Single cells or specific cell types frequently required for blood-based assay; tissue processing required for FFPE samples; tissue processing required for DNA and RNA
Function assessment Not necessary - a determinant of the static molecular status Functional assays often require ex vivo response to stimuli
Time for archived clinical samples analysis Relatively short, <1 yr Often long >1 yr; Depends on the stability of biomarker/assay
  1. Source: Guidance for Industry: Bioanalytical Method Validation [178]