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Biomarkers 101: Intro to Biomarker Analysis

The US FDA’s BEST (Biomarkers, Endpoints, and other Tools) Resource is a biomarker and endpoint terminology and application glossary for basic medical research, medical product development, and clinical care. The BEST Resource is intended to improve communication, align expectations, and increase scientific understanding. In summary, it harmonizes terms used in translational science and medical product development, focusing on terms related to biomarker analysis and clinical study endpoints. In this blog, we will dive into a number of key topics the BEST Resource addresses, to define and categorize biomarkers and the process of biomarker validation.

What is a Biomarker?

The term biomarker is short for “biological marker.” In general, a biomarker is a measurable substance that is used as an indicator of a biological process within a cell or organism. Biomarkers are critical to the development of drugs and medical devices and, according to the BEST Resource, are “used to measure normal biological processes, pathogenic processes or responses to an exposure or intervention.”

Categories of Biomarkers

Biomarker strategies can be categorized into the following groups:

  • Susceptibility/risk
  • Diagnostic
  • Monitoring
  • Prognostic
  • Predictive
  • Safety
  • Pharmacodynamic/Response

Figure 1. Biomarker categories

Susceptibility/Risk Biomarkers

Susceptibility/risk biomarkers are associated with increased, or in some cases, decreased, chances of developing a medical condition in individuals that do not yet have that medical condition. Susceptibility/risk biomarkers serve to guide preventative strategies in clinical practice, while in medical product development, susceptibility/risk biomarkers may be useful for clinical trial enrichment. For example, certain biomarkers may be monitored to enable targeted use of vaccines in patients who are most likely to develop a specific disease.

Diagnostic Biomarkers

Primarily, diagnostic biomarkers are used to confirm or detect the presence of a particular disease or condition. Additionally, diagnostic biomarkers can be used to identify a subtype of a specific disease within a person (e.g. HER-2 positive/negative breast cancer). In a clinical setting, diagnostic biomarkers are critical tools physicians use, along with empirical observations and physical exams, to quickly and accurately diagnose a patient with disease.

Monitoring Biomarkers

The BEST Resource describes monitoring biomarkers as biomarkers that are assessed repeatedly over time, and can be used to assess:

  • Disease progression, including the occurrence of new disease effects, worsening of previously existing abnormalities, or change in disease severity or specific abnormalities
  • Response of a disease or condition to a treatment, either favorable or unfavorable.

Prognostic Biomarkers

Prognostic biomarkers are used to identify the increased or decreased likelihood of a future clinical event, disease recurrence, substantial worsening in condition, or disease progression in individuals with a specific disease or medical condition. Clinical trials often use prognostic biomarkers as an eligibility requirement, which provides an opportunity to identify participants who are more likely to have disease progression or clinical events throughout the course of a clinical trial.

Predictive Biomarkers

Predictive biomarkers provide information about treatment benefits and can be a target for therapy. They are used to identify patients and individuals who are more likely to respond when exposed to a certain medical product or environmental agent. These responses can include symptomatic benefits, improved survival, or an adverse effect. It is important to note that predictive biomarkers don’t guarantee benefit. Predictive biomarkers are often confused with prognostic biomarkers. To better understand the differences between them, check out the graphic below.

Figure 2. The differences between prognostic and predictive biomarkers

Safety Biomarkers

Safety biomarkers are critical to successful drug discovery and development and are a specific marker of early clinical injury, which informs safety assessments throughout drug discovery and development (i.e., hepatic panels). For difficult targets, including those with novel disease indications and known narrow therapeutic indices, identifying and qualifying preclinical safety biomarkers that have “fit-for-purpose” translational specificity and sensitivity is vital.

Pharmacodynamic/Response Biomarkers

Pharmacodynamic/response biomarker levels change in response to an exposure to an environmental agent or medical product. Pharmacodynamic/response biomarkers can be used to:

  • Provide early evidence that a treatment may have an effect on a clinical endpoint of interest
  • Assess a pharmacologic endpoint related to safety concerns
  • Provide useful information for patient management decisions
  • Medical product development to assess pharmacodynamic effects related to clinical effects

The FDA’s BEST Resource states that pharmacodynamic/response biomarkers may be useful to establish proof-of-concept that a drug produces a pharmacologic response in humans thought to be related to clinical benefit and to guide dose-response studies. It is often very difficult to statistically power an early phase clinical trial to demonstrate a meaningful change in a clinical outcome, and many clinical outcomes require a long period of time before a meaningful change can be demonstrated. In these cases, pharmacodynamic/response biomarkers can provide evidence of target engagement.

Biomarker Validation

Figure 3. Biomarker validation progression pathway

For biomarker analysis, it is critical to establish that the test measures what was intended (i.e., analytical validation) and that the biomarker test can predict or measure relevant clinical concepts (i.e., clinical validation).

Analytical Biomarker Validation

Analytical biomarker validation ensures and establishes that when a specified protocol is followed, the performance characteristics of the biomarker assay or device are acceptable and meet established accuracy, specificity, precision, and other performance criteria.

Clinical Biomarker Validation

Clinical biomarker validation confirms that the test or device performs as intended and identifies, measures, or predicts the clinical, biological, physical, or functional state that it is intended to capture or exhibit.

Choosing the Right Bioanalytical Partner for Your Biomarker Analysis

Choosing the right bioanalytical partner is just as critical as biomarker identification throughout the drug development lifecycle. Avomeen’s team of consultative, expert scientists stand ready to support drug development from discovery through clinical trial and beyond. When you partner with Avomeen, you can expect high-quality results and biomarker analysis delivered when you need it – you won’t be waiting for months before your project starts. From bioanalytical method development, transfer, and validation to cytotoxicity, clearance assays, DMPK support, and therapeutic drug monitoring (TDM), our team offers comprehensive bioanalytical support for both routine bioanalysis and complex problem-solving.

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Additional Resources

Learn more about the use of biomarkers in drug development

Biomarkers are a critical tool for therapeutic drug monitoring (TDM) – know more

Why do we love biomarkers so much? Check out our top 3 reasons


Our featured expert is Kevin Gorman, Ph.D., Avomeen’s Manager of Bioanalytics. Kevin’s extensive knowledge of protein biochemistry and molecular biology enables him to provide clients with expert strategic and tactical guidance to help them reach their goals. Kevin has experience in analytical method development, validation, and optimization of test methods in cGMP settings per ICH guidelines. In addition, Kevin has experience developing in-vitro diagnostics, including a serology assay for COVID-19. He is listed as a co-inventor on three patents, and is highly skilled in several research techniques including LC-MS, HPLC, ddPCR, and ELISA.