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Tuesday Feb 10, 2015

President's Focus on Precision Medicine Could Be Catalyst for Change

In his recent State of the Union address, President Obama outlined plans for encouraging a shift toward precision medicine(www.whitehouse.gov), specifically citing the need for further research into personalized treatment of cancer.

Precision medicine is loosely defined as using the maximum amount of information about a patient and his or her disease process to create the best possible treatment regimen. More precisely, it involves studying genetics, proteomics, metabolomics, epigenetics and other molecular-level analyses to quantify and characterize a disease process as thoroughly as possible and using that information to formulate targeted treatments. This means not only sequencing the genome for each patient, but looking at the environment in which those genes are transcribed and translated and how that contributes to the physiology of disease. How does activation of gene A in the presence of excess protein B affect the growth of tumor cell Z? Does that change if the patient was exposed to chemical C while in utero? Will these interactions facilitate or inhibit response to medication D?

To help in boosting our understanding of how these factors interact, the president's initiative(www.whitehouse.gov) calls for $130 million to study the biomedical data of at least 1 million volunteers; $70 million to identify genomic drivers in cancer; $10 million to build a regulatory structure for precision medicine; and $5 million so information technology systems can exchange data securely. If successful, we will be able to characterize disease in new and specific ways and avoid harmful or unnecessary therapies.

The ability to practice precision medicine will fundamentally change the diagnosis and management of chronic and acute disease seen in the primary care setting. No longer will we make educated diagnostic guesses or label diseases based solely on symptoms. Precision medicine offers the potential to diagnose disease on a molecular level, allowing for targeted treatment with significantly lower chance for failure. Genetic screens already help us determine which patients will respond favorably to drugs such as warfarin or clopidogrel. Molecular analysis of cancer cells can lead to drugs that target only cancerous cells and spare healthy tissue.

In the future, medications and other treatments will no longer be one-size-fits-all. Rather, each patient will know which drugs will interact favorably with his or her personal biology and which can lead to life-threatening side effects. Although entirely new classes of medications may arise, we won't necessarily need them for tailored treatment. Instead, we will know when existing medicines can provide the most benefit. Patients with hypertension refractory to treatment with ACE inhibitors will be differentiated from those receptive to calcium channel blockade, speeding up the time to effective disease management and avoiding untoward side effects.

During this transitional period, primary care physicians will likely be called on to parse both subjective and molecular data into something manageable. We will provide molecular screening, much like we currently screen on a macro level for colorectal or cervical cancers. Bedside or serum tests for genetic markers or certain proteins could become as quick and easy to administer as a rapid group A strep test is today. Patients will have access to information about which foods and medications may interact with their personal biology -- both favorably and poorly. Family physicians, many of whom are already focused on preventive care, will have the tools to help prevent chronic diseases on an individual basis, long before pathology arises.

Unfortunately, there are hurdles. Not only is the president's plan far from a done deal, the required molecular analysis comes at a steep price. Although rudimentary genome sequencing may cost as little as $300, analysis of this information is only the beginning. Activity such as post-translational modification of proteins can vary significantly between individuals, and the techniques used to assess this information can cost thousands of dollars. Of course, this comes at a time when roughly one-fifth of Americans younger than age 65 already spend more than 10 percent of their income on health care or insurance, according to AARP(www.aarp.org).

Savings may be realized by a more targeted approach to treatment, but the front-end cost will be substantial. Not only is analysis expensive, but reams of data will be generated about each patient. Sequencing for a single individual will create thousands of data points covering multiple pathologic disciplines. These data have to be analyzed and classified to be useful. Scientists and researchers are still developing the framework for interpreting this glut of information.

Access will also be an issue in the early stages of our transition to personalized care. Most practices and labs don't currently own or use the equipment required; procuring that equipment will add significantly to costs. Finally, unlike traditional epidemiology, molecular pathology focuses on individuals or similar groups, and results aren't meant to be generalized to large swaths of the population. Identical populations, even identical twins, may have vastly different requirements and responses to treatment. For example, not all colon cancers are created equal, even in the same individual across his or her lifetime. Each cancer will require the full spectrum of analyses and individualized treatment.

Although these hindrances are extensive, they are far from insurmountable. As the testing becomes cheaper and more ubiquitous, our understanding of how each of the pieces fits together will evolve and change. We still have a long way to go before personalized medicine is the norm, but the president's plan serves as a catalyst, encouraging scientists to accelerate the rate of knowledge-gathering and incentivizing new and cheaper technologies and testing.

Gerry Tolbert, M.D., is a board-certified family physician who practices in northern Kentucky. A lifelong technophile, his interests include the intersection of medicine and technology. You can follow him on Twitter @DrTolbert.

Posted at 03:05PM Feb 10, 2015 by Gerry Tolbert, M.D.

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