Summary of Desired Characteristics for Surrogate Biomarkers for Selected Trial Types*
| Type of trial | Desired characteristic | Definition/description | Related BEST categories |
|---|---|---|---|
| Surrogate biomarker endpoint | Reproducibility | Degree to which repeated measurements show same results | Pharmacodynamic response, surrogate endpoint, predictive, prognostic |
| Quantifiability | Ability to measure changes in activity | ||
| Test–retest reliability | Consistency of test across multiple administrations | ||
| Intraobserver variability | Difference in repeated measurements by same observer | ||
| Interobserver variability | Difference in measurements between observers | ||
| Molecular targeting trials | Target specificity | Ability of biomarker to specifically bind to particular molecular target within disease process | Monitoring, safety |
| Binding affinity | Strength of interaction between molecule (such as drug) and its specific target (such as receptor or protein) | ||
| Diagnostic trials | Sensitivity | Ability of test to correctly identify patients with condition | Diagnostic |
| Specificity | Ability of test to correctly identify patients without condition |
↵* Surrogate biomarkers could be used as endpoint in intervention trial or to investigate ability of agent to reach and bind to molecular target (molecular targeting trial). Biomarkers could be used for disease diagnosis in trials where development of disease is outcome of interest. Biomarkers can also be categorized according to BEST.