Personalized Medicine

Can you imagine a time when doctors will be able to tell you with a degree of certainty what your chances are for developing a chronic disease and prescribe a drug based on your genetic profile that will significantly reduce your risk? That day may be closer than you think.

"P4 Medicine"—predictive, personalized, preventive, participatory—is coming in the next five to ten years, according to Leroy Hood, PhD, MD, a pioneer in systems biology who invented the genome sequencing technology that led to the decoding of the human genome in 2001.

Writing in Newsweek earlier this year, Dr. Hood describes how advances in technology will change medicine "from its current reactive mode, in which doctors wait for people to get sick, to a mode that is far more preventive and rationale." Physicians of the future will use a patient's genetic information as well as information about how the patient's behavior and interaction with the environment may increase their risk for disease.

New Device for In-office Gene Testing

Analyzing a person's genetic inheritance to determine how he or she will respond to a drug (pharmacogenomics) has been used for a number of years with some cancer medications. While the technology is available to assess individual response to drugs for other diseases and conditions, e.g., HIV, epilepsy, high blood pressure and pain, among others, time for laboratory analysis and the high cost of testing have slowed widespread adoption by physicians.

Recent FDA approval of new desktop instrument called Verigene made by Nanosphere (http://www.nanosphere.us) may be a step toward making pharmacogenomics testing more widely available. Verigene, which is designed for use in hospitals and doctors' offices, uses a blood sample to analyze DNA. It comes with different modules (for different types of testing) that range in price from $40,000 to $80,000.

The first application for Verigene is for warfarin, a potent blood thinner whose optimal dose can vary tenfold among patients. Two specific genetic variations that affect a person's response to warfarin have been identified and are included in the product's labeling but currently available laboratory testing methods are complex, expensive, and, as a result, not used routinely.

Instead physicians give an intermediate dose of the drug and monitor and adjust carefully over the course of several weeks until the optimal dose is achieved for the individual patient. A relatively quick test done in the doctor's office or coagulation clinic could greatly enhance the safety, effectiveness, and efficiency of warfarin dosing.

Pharmacogenomics tests for Plavix as well as genetic screening tests and virus detection are also in development at Nanosphere. If the Verigene technology delivers on its promise, new applications in pharmacogenomic testing will undoubtedly follow.

Questions About Privacy, Ownership and Clinical Use

Last year, after the bill was debated in Congress for 13 years, President Bush signed into law the Genetic Information Nondiscrimination Act (GINA) that will protect Americans against discrimination based on their genetic information when it comes to health insurance and employment. And while major initiatives are underway among scientists, physicians, and policymakers to create an infrastructure for personalized medicine, many questions remain about privacy and ownership of data and methods for collecting, disseminating and integrating genetic information into clinical practice.

As technology evolves, new markers are discovered and validated, and standards of testing are refined, genetic tools of the future will give us, as Dr. Hood says "unparalleled opportunities" to take control of our health. With those opportunities come the responsibility for each of us to be an informed participant in the upcoming public debate about the questions surrounding personalized medicine.

Note: Obviously this is a very complex subject and I've barely skimmed the surface. If you are interested in learning more about genetics and pharmacogenomics, the links in the Resources section below may be a good starting point.

References

A Doctor's Vision of the Future of Medicine by Leroy Hood. Newsweek, published on line 6/27/09. Accessed 12/1/09 at www.newsweek.com/id/204227

Gene-Testing Machine for Doctors by Emily Singer. Technology Review Published by MIT, 12/2/09. Accessed 12/21/09 at www.technologyreview.com/printer_friendly_article.aspx?id=24042&channel=biomedicine&section=

Resources

Genetics and Genomics for Patients and the Public provides information about genetic disorders, background on genetic and genomic science, pharmacogenomics, tools to create your own family history and a list of online resources. http://www.genome.gov/19016903

Help Me Understand Genetics Handbook published by the National Institutes of Health. http://ghr.nlm.nih.gov/handbook

http://www.warfarindosing.org/Source/Home.aspx a site for doctors and other clinicians developed through international collaboration of biostatisticians, geneticists, pharmacists, and physicians who share anonymous data to improve warfarin dosing. Includes patient education materials.