Biological markers endpoints

Endpoint. An indicator measured in a patient or biological sample to assess safety, efficacy, or another trial objective. Some endpoints are derived from primary endpoints (e.g., cardiac output is derived from stroke volume and heart rate). Synonyms include outcome, variable, parameter, marker, and measure. See surrogate endpoint in the text. Also defined as the final trial objective by some authors. 

Much of the discussion about disease biomarkers is in the context of markers that measure some aspect of disease status, extent, or activity. Such biomarkers are often proposed for use in early detection of disease or as a surrogate endpoint for evaluating prevention or therapeutic interventions. The validation of such biomarkers is difficult for a variety of reasons, but particularly because the molecular pathogenesis of many diseases is incompletely understood, and hence it is not possible to establish the biological relevance of a measure of disease status. 

Marker compounds, compounds with a known biological endpoint, used to produce predictive equations. 

Kinetic studies are important for the safety evaluation of interferons and interleukins. Both pharmaco- and toxicokinetics have been evaluated in single- and, in some cases, multiple-dose studies. Use of pharmacodynamic endpoints or serum markers of biological response are especially important in those cases where the serum levels are lower than the limits of detection of the assay for the test material. In addition, studies to investigate the accumulation of (modified) products with long half-lives in relation to the dosing regimen are useful. Tissue distribution studies have not been components of the safety evaluation of interferons and interleukins. 

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