Personalised Medicine

Perspective What happens when one size does not fit all? Personalised Medicine

The first race-based combination pre‐scription drug, Hydralazine-plus-ni‐trate is used in the treatment of congestive heart failure. Among African Amer‐icans, life expectancy of those with heart failure is increased using this combination drug, whereas white Americans respond less effect‐ively to the drug. Another drug, Gefitinib, used in the treatment of certain cancers such as breast and lung cancer is more effective in Japanese than American patients as evidenced by clinical trials.

Therapeutics would be much easier if the same dose of drug always produced the same response. Enabling research to improve drug efficacy and minimise side effects. However, in reality, genetic and lifestyle variations between individuals, play a major role in how an indi‐vidual responds to a given drug. Personalised medicine and Pharmacogenomics testing offer the possibility of more precise therapeutics for several drugs and disorders. Personalised medi‐cine (precision medicine), is the concept of in‐dividualising drug therapy using the genomic information of an individual. Pharmacogen‐omics, also called pharmacogenetics or druggene testing, focuses on how an individual’s genes affect their response to medication. This is a field of intense research activity, rapid pro‐gress and high expectations. However, proving these tests add to present health diagnosis and improve patient outcomes remains a challenge. As researchers continue to look further into disease pathways and how drugs affect them, personalised medicine has the potential to in‐crease the quality of clinical care and become an

essential tool in medicine. The example ofGe‐fitinib: Researchers observed that Japanese pa‐tients over-express a certain protein: Epidermal Growth Factor Receptor (EGFR). Gefitinib works by inhibiting EGFR and consequently decreasing its activity. EGFR is a protein found in both normal cells and cancer cells. However, its over-expression can be a result of mutations. These mutations can cause EGFR to be con‐tinuously activated, leading to uncontrolled cell division, one of the hallmarks of cancer. Using this information, patients can be prescribed more personalised targeted therapy.

The use of pharmacogenomic testing can help healthcare providers determine the best medication for a patient. These tests can help determine the effectiveness, optimum dose and possible side effects of a drug. There are several pharmacogenomic tests currently in use for this purpose. One of these is the CYP2D6 genetic test, which tests for variants of this gene, pre‐dicting how patients will respond to different medications for the treatment of a variety of conditions like breast cancer, depression and anxiety disorder. Information from this test shows how a patient will metabolise a given drug, which can affect their responsiveness to it. “Therapeutics would be much easier if if the same dose of drug always produced the same response.”