The great promise of personalized medicine

The great promise of personalized medicine

By Michael O. Leavitt and Raju Kucherlapati | December 26, 2008

A PATIENT is diagnosed with non-small-cell lung cancer. A DNA test costing $1,000 reveals the subtype of his cancer. The test indicates that the most effective treatment will be an oral drug rather than chemotherapy. Thus, through genetic testing of the tumor, the patient is treated more effectively and with a longer survival benefit.

A woman with atrial fibrillation, a heart condition, is prescribed the widely used blood-thinning drug warfarin. A $350 genetic test is performed, looking for variations in two specific genes that affect the body's metabolism and response to the drug. Combined with other factors, the test indicates a proper dosage range for her. Thus, with a test that looks at her genetic profile, she is prevented from suffering uncontrolled bleeding or life-threatening blood clots and risk of stroke that can accompany the use of this powerful drug.

These are examples of personalized medicine in practice. Of course, physicians have always been alert to variations between patients. But the term "personalized medicine" reflects the growth of scientific understanding and medical tools that can help individualize care at a new level. Such tools can help match treatments to individual genetic variations, or differentiate between subtypes of disease. And that can help take the guesswork out of medicine, making healthcare decisions more precise and effective, often at lower cost.

The opportunity of personalized medicine stems from advances in molecular biology, especially the explosion of new knowledge of the human genome. It is already working for patients with some conditions, and it has the potential to transform the effectiveness of medical care in the immediate future.

For example, most drugs prescribed in the United States are effective for fewer than 60 percent of treated patients. This is not because of shortcomings of the drugs, but rather because each of us is biologically unique. The tools of personalized medicine can help direct the right treatment to the right patient. The potential improvements in health as well as savings in health costs are vast.

Likewise, our conception of disease needs to be more precise in order to better individualize care. For example, when we refer to asthma, it is a respiratory disease but there are many varieties. From a treatment perspective, they are different diseases, but we are just at the cusp of identifying them accurately and providing the right treatment on the first encounter. We refer to breast cancer, yet in reality there is no such single disease. Rather, cancers of different kinds may arise in breast tissue. One result is that most women who are treated with painful and expensive chemotherapies are receiving treatments that are actually ineffective for their condition.

With personalized medicine, we can improve the current paradigm. The explosive growth of scientific discoveries at the molecular level, accompanied by advances in technology and analytical capabilities, bring the promise of greater precision and effectiveness in medicine. Over time, we should be able to prescribe medicines with foreknowledge as to their effectiveness for individual patients and disease subtypes.

Over time, increased knowledge of genetics and molecular biology should also enable us to detect disease before symptoms appear, making possible earlier treatment and even preemption of the disease.

Personalized medicine, as promising and as transformative as it is, cannot be implemented if it is going to result in a great increase in healthcare costs. But the practice of personalized medicine can be an important part of achieving higher value in healthcare. In the case of warfarin, for example, adverse events related to dosage problems make this drug a leading cause of drug-related emergency room episodes. More accurate dosing, enabled by a relatively low-cost genetic test, might save as much as $1 billion per year while delivering better-quality care and better health.

We have an important opportunity to improve health and improve value in healthcare. Let us make personalized medicine an explicit goal of healthcare reform.

Michael O. Leavitt is secretary of health and human services. Raju Kucherlapati is a professor of genetics and medicine at Harvard Medical School.

http://www.boston.com/bostonglobe/editorial_opinion/oped/articles/2008/12/26/the_great_promise_of_personalized_medicine?mode=PF