Each person is an individual and there are no exceptions.
Personalised medicine is the study of how inherited variations in an individual’s genes affect how the body processes and responds to medications making it possible to tailor treatment to the person’s genetic profile.
In June 2007 I wrote for the first time about this amazing, revolutionary, new field of Medicine. One more time I revisited the subject in April 2012 and, when considering the subject for my next article, it came back to my mind… as there has been a non stop, fast evolution of Pharmacogenetics.
Genes, Dreams, and Reality
In old times, the knowledge, the art and the flair, were basics for a doctor to be “a good doctor”.
It has always been considered very important to know the person that is being treated, in order to achieve the best treatment according to the individual physical and psychological characteristics.
One of my favorite statements has always been “patients are not in the books, only diseases” as diseases present differently in different individuals and individuals react differently to the same treatment. In medicine, one size does not fit all.
Two people who take the same medication may have very different responses from severe, even life-threatening side effects, to few, if any side effects. A drug may be effective to treat a certain disease in one person but not in another.
Why does this happen? Blame the genes, the smallest units of heredity, as it is their fault if two people have drastically different reactions to the same medication. The way medication choices generally work today is often a matter of trial and error. Due to the evolution of genetics, doctors have available and are using, a progressively larger amount of tests to detect some of these genetic variations and predict how people are likely to respond to certain medications, thus customising treatment based on a person’s specific genetic characteristics, particularly in the area of cancer. Genetic tests eventually will make it possible to tailor drug therapy.
When the human genetic code was cracked about 10 years ago, it brought with it the expectation of immediate application to human disease as virtually all diseases except trauma have a genetic component. Humans vary in their responses to drugs. Genetic factors may account for 20-95% of this variation.
One day, hopefully, each patient will have his tailor made personalised treatment, his own, unique, treatment.
Personalising medicine with clinical pharmacogenetics
Pharmacogenetics is the study of inherited genetic differences in drug metabolic pathways which can affect individual responses to drugs, both in terms of therapeutic effect as well as adverse effects.
Clinical DNA-based testing began in 1978 and it has grown substantially over the past 30 years.
As scientists learn more about individual genetic variations, the potential of personalised medicine grows. Although many of the first available tests for genetic variations were most useful in alerting doctors about the likelihood of a severe adverse reaction to a drug, there are a growing number of tests to determine whether someone will respond to a particular medication making it possible to predict if a medication will actually help improve their condition.
Many recent genome-wide association studies (GWAS) have identified genes that contribute to some common diseases and complex traits, prompting the possibility of predictive genetic testing to evaluate personalised disease risk and the use of pharmacogenetic biomarkers to facilitate more effective drug therapy. Pharmacogenetics has become one of the leading and potentially most actionable areas of personalised medicine.
Changing the Future of Health Care
With personalised medicine, before taking a single dose of medication, you may be able to have a blood test to see which genetic variations you have and your unique genetic profile can help your doctor personalise your treatment.
Pharmacogenetics is based on the understanding that all drugs are taken through several biochemical pathways to break them down, after they are administered. The body needs to eliminate these drugs and does it by breaking them down through biochemical pathways, created by our genes, that are explicit for each and every pharmaceutical drug. For people that cannot biochemically break down the drugs in a normal fashion, the levels in their blood get very high and that contributes to bad side effects and even allergic reactions. One of the reasons for these problems is that the person does not have the genes that create the biochemical pathways to break down the medication.
The tests give us a chart showing which drugs your body is programmed to be able to break down in the normal fashion and which drugs you will not be able to. The companies do this for all categories of drugs including high blood pressure drugs, gastrointestinal drugs, urological drugs and even psychotropics and anti-anxiety drugs. This has application in all fields of medicine.
If a patient breaks down too quickly a certain pain relieve medicine, the medicine will not work as it will not have enough time to be effective. This patient must be given a different drug that the tests showed his metabolism can properly deal with.
Imagine someone is depressed and needs to start a psychotropic drug. Wouldn’t it be nice to know which drugs they have the pathways to break down? This is the power of pharmacogenetics.
This test is a once-in-a-lifetime test, does not need to be repeated because it shows which drugs genes can and cannot break down, based on individual DNA.
Advances in personalised medicine will create a more unified treatment approach specific to the individual and their genome providing better diagnoses, earlier intervention and more efficient drug development and therapies.
Personalised medicine may be able to reduce the number of deaths and hospitalisations from adverse reactions to drugs, avoid spending a lot of money trying medications that ultimately will not work and also reduce the cost of developing drugs by speeding up the clinical trial process.
This “next revolution in medicine” will fall on the shoulders of family physicians who provide primary care as they will face a challenging demand to provide information on genetic testing to their patients, help interpret test results for them and consider prescribing new genetic therapies that will become available.
The success of any type of personalised medicine will be critically dependent on accurate diagnosis. Of course, no doubt about it, a good doctor will still be necessary.The human factor cannot be forgotten. Even without the genetic factor, there is a lot that can be done to personalise treatment when there is a good patient/doctor relationship.
We should look forward to the future without neglecting what has always been there and has proved to be important.
Doctors should never forget to “look at the patient” whilst waiting for the future.
The future is coming now…
Best health wishes,
Dr. Maria Alice
Consultant in General and Family Medicine
General and Medical Director- Luzdoc International Medical Service
Medical Director- Grupo Hospital Particular do Algarve