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What are biomarkers? Biomarkers are anatomic, physiologic, biochemical, or molecular parameters associated with the presence and severity of specific disease states. Biomarkers are detectable and measureable by a variety of methods including physical examination, laboratory assays and medical imaging. What is the difference between biomarkers and surrogate endpoints? Surrogate endpoints, as used in the scientific and regulatory communities, are findings or measurements that may be used in clinical trials to evaluate the safety or effectiveness of a medical therapy for treating disease. They serve as an alternative to traditional trial endpoints such as morbidity and mortality, and often may be gathered in a shorter timeframe or evaluated with higher confidence. Biomarkers in imaging may serve as such non-traditional endpoints, though many if not most surrogate endpoints do not involve the imaging of biomarkers, and the concepts are not synonymous. How may biomarkers be visualized? Biomarkers may be visualized with clinically proven imaging methods such as x-rays, computed tomography (CT), magnetic resonance imaging (MRI), or nuclear medicine techniques such as positron emission tomography (PET). In addition to these established techniques, there are a variety of imaging methods in various stages of development that hold great promise in the imaging of biomarkers, such as molecular imaging, a method that allows detection of specific molecules in living organisms. What are examples of biomarkers in everyday medical imaging? Perhaps the best-known biomarker is the presence and size of a tumor in cancer, but there are large number of biomarkers that are commonly evaluated with modern imaging. For example, in the brain and central nervous system, white matter abnormalities seen by MRI are associated with multiple sclerosis. Simple x-rays can demonstrate a variety of diagnostic changes associated with arthritis. Are there advantages to using biomarkers in the evaluation of new drugs and devices? An important consideration in evaluating new drugs and devices is determining whether a product can effectively treat a target disease. In many instances, this requires trials in animals and humans. Traditional trial endpoints, such as morbidity and mortality, may be subjective, difficult to evaluate, or require a long timeframe. Biomarkers in imaging may, in many instances, provide objective endpoints that may be confidently evaluated in a reasonable timeframe. Are there potential pitfalls to the use of biomarkers as clinical trial endpoints? As with any technology used to assess the presence and severity of disease, biomarkers may be inappropriately applied, producing false or misleading results. For example, measurement of stenosis in an artery narrowed by atherosclerotic disease is a biomarker that may be used to assess reduction in blood flow. However, direct measurement of stenosis may be quite misleading, as a stenosis does not meaningfully restrict blood flow until a critical narrowing is reached. Given such pitfalls, it is crucial that biomarkers/surrogate endpoints only be employed by knowledgeable investigators who understand both their strengths and limitations. | Home | About Us | Biomarkers Catalog | Center Membership | FAQs | Useful Links | |
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