Genetic testing may identify personalized treatments

Have you ever wondered why one drug works for one patient and not another? The answer may lie in pharmacogenomics. This growing field of personalized medicine studies how a person’s unique genetic makeup affects their response to medications and drugs.

“Just as our genes determine blood type and eye color, they are partly responsible for how our bodies respond to drugs,” says Murray Markman, MD, chief of medicine and science at Cancer Treatment Centers of America. ^® (CTCA). “Pharmacogenomics looks for changes in these genes that can determine whether a drug could be a viable treatment or cause specific side effects.”

Genetic factors and pharmacological treatments.

The field of study works by genotyping testing to see how patients can process a variety of drugs, including cancer treatments. Differences between individuals can affect the absorption, metabolism, or activity of a drug. “The only way to treat cancer is fast becoming a thing of the past,” says Dr. Markman. “It is being replaced by drugs and therapies that directly target a patient’s individual DNA.”

Currently, doctors base most of their prescriptions on clinical factors, such as the stage of the cancer and the age and sex of the patient. But a person’s genetics can be just as important as clinical factors. For a small subset of the drugs, the researchers identified genetic differences that affect how people respond. In these cases, clinicians can use pharmacogenomic information to choose the drug that is most likely to work and to identify people who need an unusually high or low dose.

The US Food and Drug Administration, which monitors the safety of all drugs in the United States, has included drug genetic information on the labels of more than 150 drugs. This information, which may cover dosing recommendations, potential side effects, or differences in effectiveness for people with certain genetic differences, can help clinicians tailor their drug prescriptions to individual patients.

Frontiers of pharmacogenomics

But there are limitations. Pharmacogenomics does not provide information on how patients respond to all medications. Some may need more than one test if they are taking more than one type of medication. “The tests are not a crystal ball. They cannot determine the ideal drug for your condition or provide information on drug interactions,” says Dr. Markman. “Alternatively, pharmacogenomics testing can narrow down your options and help clinicians prescribe the correct medication faster.”

Although the use of pharmacogenomics is limited, new approaches are being studied in clinical trials. The ultimate goal is to develop tests that will lead to the development of customized drugs to treat a wide range of health problems, including different types of cancer. “Precision medicine in cancer care is developing at a rapid rate,” says Dr. Markman. “Pharmacogenomics is also expected to become more standard as precision medicine is becoming more and more popular.”

Learn more about the precise treatment of cancer.