BACKGROUND ON BIOMARKERS

The number of innovative medical therapies that have reached the market has been disappointing, given escalating research investment. One major reason for the slowdown has been the paucity of suitable biomarkers that might streamline the clinical testing of putative therapies. Biomarkers are quantitative biological measurements of many types that provide information about a disease state or a response to treatment, in addition to other disease characterizations.

One common category of biomarkers is used to identify people at risk for a disease; others are used to diagnose disease, assess its progression, or predict disease outcome. In the therapeutic setting, biomarkers can reveal information about whether a drug is adequately engaging its intended target or what therapeutic side effects or efficacy to expect. Of considerable interest to the pharmaceutical industry is the category of biomarkers known as “surrogate”1 biomarkers, which are qualified indicators that can substitute for clinically meaningful endpoints in clinical trials (U.S. Department of Health and Human Services, 2006). Surrogate markers are sometimes used to substitute for clinical endpoints. Often they are used to reduce the time or study size needed to determine the response to a candidate treatment, thus shortening the path to use in a clinical setting. A biomarker of any type may be used individually; if a biomarker is used in combination with another biomarker, the two (or more) are sometimes referred to as a “biosignature.” An example of a biosignature would be a composite measure of imaging and genomics that offered improved diagnostic sensitivity and specificity compared to that of either measure alone.

The expected value of biomarkers to the pharmaceutical industry is to increase the efficiency of drug development, thereby permitting more drug candidates to be brought forward and perhaps increasing the information gleaned from the trials performed. The expected value to public health and to individual patients is to hasten access to safe and effective therapies. For these reasons, all potential partners have a stake in and stand to benefit from biomarker development.

There is a great need for new biomarkers for nervous system disorders, observed Dr. Dennis Choi, executive director of Strategic Neurosciences Initiative and Director of the Comprehensive Neuroscience

1

The Food and Drug Administration (FDA) defines a surrogate endpoint as “a biomarker that is used to predict clinical benefit (a direct measurement of how a patient feels, functions, or survives).”



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