Comparison of bioanalytical assays with immune response-based assays

CharacteristicsBio-analytical AssaysImmune-based Assays
Number of analytesSingle analyte relative to biological functions (small molecules or macromolecules)Multiple analytes with complex functional relationships between tumor and immune system
Category of measurementAbsolute quantitationQuasi-quantitative, relative-quantitative or qualitative. Qantification is available for specific assays
Reference materialAvailableNot available, limited availability or available - depends on the assay
Linearity of analyte(s)KnownUnknown or do not demonstrate linearity, often unknown dynamic ranges, or dynamic range can be established-depends on the assay
Limit of detection (LOD)AvailableNot quantifiable or LOD available - depends on the assay
Sample processingExtraction required for small molecules; Direct measurement in biological matrix without sample pretreatmentSingle 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 assessmentNot necessary - a determinant of the static molecular statusFunctional assays often require ex vivo response to stimuli
Time for archived clinical samples analysisRelatively short, <1 yrOften long >1 yr; Depends on the stability of biomarker/assay

Source: Guidance for Industry: Bioanalytical Method Validation [178]