You are here: MEDICA Portal. MEDICA Magazine. Topic of the Month. Volume archives. Our Topics in 2010. May 2010: Medicine in the Future. Blood.
“A Genetic Test for Your Graduation Present“
How drugs are metabolized in the
body is genetically determined;
MEDICA.de: Mr. Roots, physicians hope for the so-called personalized medicine in the future. Why do so many consider this a big step forward?
Ivar Roots: Current drug therapy does not only contain positive aspects. People with the same disease do not always react the same way to the same drugs. For some patients specific treatments work, but they don’t work for others and for yet others it causes side effects. Our genetic blueprint is responsible for that. If you know the patient’s individual genetic factors, you can adapt the treatment much better to him/her. There is a lot of research in this particular area.
MEDICA.de: How can you actually figure out, which patient responds to which drug?
Roots: At the moment, we use the trial-and-error-principle for many diseases. The patient is administered a drug and you see if it works. With pills for a stroke or a heart attack, this possibly could have disastrous consequences.
MEDICA.de: How can you determine whether the drugs work?
Roots: There are different ways, which differ depending on the disease. If somebody takes a high blood pressure drug and the blood pressure drops when measured, the drug works. For cancer drugs the effects are harder to prove. You could do some blood work for example. With it you can not only assess diagnostic biomarkers for diseases, but also drug-related biomarkers. Those provide clues to which active ingredients the patient is responding to. Another way is to do a genetic test, since cancer can also be triggered by genetic mutation. Some patients show similar genetic mutations. If you know which group a patient belongs with, you can administer specific drugs.
MEDICA.de: So the personalized treatment is not tailored to each individual patient, but to patient groups?
Roots: Initially, this is the case. A famous example that is already used today is the treatment for breast cancer with the drug Herceptin. It is a monoclonal antibody, that binds with the HER2-receptor and inhibits the growth of breast cancer cells. However, this drug only works for patients whose breast cancer is based on a hyper activity of the HER2-receptors. This is only the case for about one third of the patients. For all others, the targeting molecule of Herceptin is not the right area of attack. The drug is therefore ineffective for them.
MEDICA.de: Yet within a group, the patients also continue to vary.
Roots: Yes, which is why those groups need to be subdivided even further and drugs need to be individually dosed.
Prof. Ivar Roots; © private
MEDICA.de: And what is the individual dosage based on?
Roots: Drugs are metabolized in the body through enzymes, but enzymes are not equally active in each person. Some people even completely lack certain enzymes. To determine the correct dosage, this kind of information is very important. If certain enzymes are more active, they process active ingredients quicker in the body. This means the dosage needs to be increased. If enzymes are less active, drugs are metabolized slower and the dosage therefore needs to be decreased. The type of enzymes a person carries and how active they are, is genetically determined.
MEDICA.de: There also is reverse research. Pharmaceutical companies are trying to create drugs that are targeted to fit specific genetic preconditions. Does that also make sense?
Roots: Of course it is important to research for new agents that specifically fight diseases, but I see the implementation of personalized treatment less with pharmaceutical companies and their customized drugs, but rather with the physician at the hospital bed. Most drugs are already available, and ultimately it is the physician who determines which drug is best for whom and in what dosage.
MEDICA.de: Even though personalized medicine is already practiced in part, research is still not as advanced as it would like to be. What exactly makes the realization of this physician-dream so difficult?
Roots: Physicians today still don’t have the precise knowledge that they need. While the technical possibility of a complete genetic analysis already exists, it is still very expensive. That should change in a few years. I am optimistic that in the near future an analysis of all 25,000 human genes can be done for about 1,000 to 5,000 Euros.
MEDICA.de: That is still quite expensive.
Roots: You only need to test genes once in your life. I always joke by saying, that pretty soon parents can give their child a genetic test as a graduation present. You could save the test information on a smartcard for example and put it in your wallet. Compared to a MRI test, 1,000 Euros is actually not that much, because that’s also how much a comprehensive MRI costs. And those are done a lot. With a tailored treatment, health care costs can be reduced in the long run, because the wrong treatment gobbles up a lot of money and in addition means a lot of discomfort for the patient.
MEDICA.de: Which diseases have the best chances of being cured with tailored treatments?
Roots: You have to be very careful with that word. Whether we can really cure diseases with personalized treatment, is still unclear. Yet we hope that we can at least treat them better or perhaps even prevent them. We have our eye on common diseases like cancer, diabetes and Alzheimer’s disease.
This interview was conducted by Simone Heimann and translated by Elena O'Meara