Biomarkers, measurable biological signals that reflect health, disease, or drug effect, are transforming clinical research. Understanding what they are helps patients appreciate what some of the blood tests and measurements taken during study visits are actually measuring.
What Is a Biomarker?
A biomarker (biological marker) is any measurable substance, structure, or process in the body that reflects a biological state. Biomarkers can be:
- Molecular: Proteins, genes, or metabolites in blood, urine, or tissue (e.g., elevated CRP indicating inflammation, APOL1 gene variants indicating kidney disease risk)
- Cellular: Counts or activity levels of specific cell types (e.g., eosinophil count in atopic dermatitis)
- Imaging: Changes visible on ultrasound, MRI, or other scans
- Physiological: Blood pressure, eGFR, skin barrier function (TEWL)
Types of Biomarkers in Clinical Trials
Diagnostic biomarkers, used to confirm or characterize disease (e.g., APOL1 genotyping to identify high-risk CKD patients).
Predictive biomarkers, predict who will respond to a specific treatment.
Prognostic biomarkers, predict disease trajectory regardless of treatment.
Pharmacodynamic (PD) biomarkers, confirm that a drug is having its intended biological effect.
Surrogate endpoints, biomarkers used as proxies for clinical outcomes, enabling faster results (e.g., reduced proteinuria as a proxy for slower CKD progression).
Why Biomarkers Matter for Participants
Many blood draws and measurements during clinical trial visits are collecting biomarker data. These help researchers understand not just whether the drug is working, but how and why it is or is not working. Your participation contributes to this deeper scientific understanding.
Browse NuLine’s active studies or learn about the trial process.