Gene Sequencing Changing the Rules of Drug Prescription

Wed, 09/09/2015 - 15:58

As a result of the sequencing of the human genome in 2003, paradigms in medical research and treatment have shifted forever. Genomic science has brought personalized medicine closer to reality. The main effects are visible in clinical trials, when test groups are targeted according to speed of metabolism of certain drugs. This filter obtains more consistent results earlier, shortening the time-tomarket for new drugs.

Precision is the key word here. Around 2.2 million severe, adverse events occur every year in the US as a result of medications. One third of these are due to interactions between genes and drugs, not between drugs and drugs. Gene variations in leukemia patients can dictate the type of treatment they can receive. Some require 10% of the stated dose. Abacavir - an antiretroviral drug effective in combination with other drugs against HIV - causes hypersensitivity in between 5% and 8% of its patients during the first six months of treatment, a reaction which is associated with a gene variant. Screenings for the variant are now a standard part of treatment with regimens containing Abacavir. In an industry where the practice is to increase dosage when a patient is not responding, pharmacogenomics can guide doctors to a less risky resolution of the issue. Finally, studying the biochemical pathways traced by psychotropic drugs may be effective in helping patients choose between an array of options based on their side effects.

Pharmacogenomics is no magic solution, of course. Drugs act across more than one gene, and genetic diseases tend to be caused by variants or mutations in more than one gene. Nor do genes act in isolation. Thinking of genes as a kind of naturally occurring switch, environmental issues are the stimulus necessary to activate or deactivate them. Without these catalysts in a person’s surroundings, genetic illnesses may remain latent throughout the lifetime of the carrier.

One indisputable fact is the long-term financial worth of investment in genomic sciences. However, few laboratory chains and independent companies currently provide pharmacogenomic or otherwise personalized treatments to the general public. In Mexico, Genomica Médica, offers six different pharmacogenomics tests including a DNA test aimed at identifying genetic variations of SLCO1B1, which encodes the metabolizing protein of the cholesterol-reducing drug simvastatin. Another test focuses on identifying genetic variations of the enzyme CYP2C19, which is responsible for the metabolism of clopidogrel.