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| It's a truism that each of us is unique...no two of us, even identical twins, have identical interests, features or life spans. |
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| One Size Fits All |
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| Equally true is that each of us has a unique blueprint inherited from our parents. And with each blueprint may come a unique predisposition for diseases and conditions ranging from cancer and diabetes to asthma and depression. Our genes also control what signs and symptoms we develop as a result of disease, how our bodies react to a disease and our response to medications. |
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| Yet, though we are unique, the medicines we take are typically "one size fits all." That is, the label on your prescription bottle may instruct you to "take two pills three times a day." It likely does not take into account whether you are male or female, short or tall, heavy or thin. Nor can massed produced prescriptions address other factors such as your age, general health or other medications you may be taking. |
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| As a consequence, one researcher - echoing the comments and concerns of many others - estimates that drugs now on the market may be effective for only about 30 to 40 percent of the patients who take them. |
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| It is perhaps not surprising that more than 100,000 people a year die from side effects that arise when they take legitimately prescribed drugs. |
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| Such "adverse side effects" typically are the result of combining mass medicine with unique genetic blueprints - blueprints that dictate different rates for metabolizing a particular drug and that can set the stage for therapeutic failure, sometimes lethal drug sensitivities or allergies. |
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| Similarly, the diagnosis of disease often relies on clinical findings (a doctor's exam) and laboratory testing that have been "standardized" based on the disease and not on the individual's signs and symptoms. As an example, some patients with extensive coronary artery disease may have abnormal blood test results while others do not. Some cancer patients develop identifiable signs and symptoms that allow doctors to quickly diagnose and treat them, while other patients with the same cancer do not exhibit symptoms until the cancer has progressed much further. |
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| Personalized Medicine |
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| In 2003, the completion of the Human Genome Project marked a critical advance in the use of genetic and related information to understand and manage disease susceptibility, diagnosis and treatment on a truly personalized basis. This 13 year international initiative, sponsored by the US Department of Energy and the National Institutes of Health, consolidated the findings of some three dozen research universities and institutions to identify the roughly 3 billion base pairs ("letters") that constitute DNA and our genes - collectively known as the human genome. |
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| Two years later, further fueling the transformation of how disease is understood, the Food and Drug Administration issued guidelines encouraging research on how genetic background affects our response to drugs. |
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| The ability to rapidly and inexpensively "read" our genetic sequence and the growing realization that individual differences in our DNA have an enormous impact on each person's disease risk, progression and treatment response have triggered a medical revolution. |
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| The advent of personalized medicine ultimately will result in abandoning the traditional "one size fits all" model in favor of a framework calling for the "right drug for the right patient at the right time." |
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| The Role of Biomarkers |
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| Central to the personalized medicine revolution is the discovery and use of biological markers - or biomarkers - that contribute to or are associated with disease and drug response. Biomarkers will fuel the next generation of safer and more effective drugs as well as new molecular tests that aid in earlier and more accurate diagnosis of disease. |
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| A biomarker is any molecular, biological or physical characteristic that underlies a specific state, whether diseased or health. For example, a biomarker may be a genetic factor that causes a disease such as breast or colon cancer. It may be a protein such as the prostate specific antigen (used in the well known "PSA" test for prostate cancer). Or it may be another form of molecule such as cholesterol-an indicator of, or surrogate biomarker for cardiovascular health. |
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| Other biomarkers include blood sugar for the management of diabetes, physical measurements such as blood pressure, and medical imaging results such as X-rays. These examples are only the tip of what some researchers refer to as the "biomarker iceberg." |
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| Biomarkers can be used to identify how well an individual is protected from disease, determine the risk or severity of disease, and provide a guide for treatment. In some cases, as with a specific form of breast cancer, they may do both: lead to a reliable means of early diagnosis of a disease and an effective regimen for treatment. |
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| Biomarkers are widely viewed as essential to the drug industry's future, not only in aiding the development of new treatments, but also in reassessing existing drugs. For example, they can help researchers identify which drugs are working for which patient populations, and uncover beneficial or harmful effects that were previously unknown. |
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| Identifying Biomarkers |
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| While many clinically useful biomarkers are employed today, the entire repertoire necessary to fully realize personalized medicine has yet to be discovered. Four primary components are required for their discovery: |
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| 1. Biosamples from individuals with the condition or disease under investigation; |
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| 2. Biosamples from individuals without the condition or disease; |
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| 3. Technology to analyze the biosamples; and |
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| 4. Detailed clinical data from the individuals so that results from the analyses can be tied to some clinically relevant and medically actionable outcome. |
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| Whether anatomic, physiologic, biochemical or molecular in nature, biomarkers' effective use requires they be measurable by some combination of methods including physical examination, laboratory assays and medical imaging. |