Is the future of pharmaceuticals really all me, me, me?
Gene tests could help doctors to identify the best treatment for each patient. Some gene variants, for example, affect how the body breaks down different drugs. Giving the right drug to the right patient at the right dose, when there is a choice, should increase effectiveness and reduce adverse reactions. A more complete knowledge of how genetics affects our responses to drugs – pharmacogenetics – could eventually lead to an era of personalised medicine.
Like disease risk, a person’s response to a drug is unlikely to be governed by one dominant allele or gene variant. In June 2013, US researchers identified two SNPs in two nearby genes that influenced how women responded to medicines for preventing breast cancer: both SNPs influenced the activity of another gene, BRCA1, which in certain forms is linked to breast cancer.
This new information suggested that use of the preventive drugs tamoxifen and raloxifene could be personalised. The researchers found that women with favourable versions of the two newly discovered SNPs were five times less likely to develop breast cancer when they took the preventive drugs than women with unfavourable versions. If high-risk women were routinely tested for these two SNPs, only those who will benefit would be given preventive drugs – sparing women who aren’t likely to respond the side-effects, which may include blood clots.
A year later, in 2014, another group of American researchers identified a pattern of gene expression (a gene-expression profile) associated with a greater risk of a fatal heart attack. They followed 338 patients with coronary artery disease for five years and examined the gene expression patterns in 31 of those patients who died of heart failure. This revealed a pattern in which genes affecting inflammation were upregulated, whereas genes affecting certain immune signals were downregulated.
Combined with other medical information and family history, the pattern could be used to assess a patient’s individual level of risk so that doctors would know when to maximise drug treatment. Many patients with coronary artery disease do not follow their drug regimens properly, but researchers think that a patient who knows they are at high risk of suffering a fatal heart attack might be more likely to comply.Lead image:
Medical Art Service, Munich, Wellcome Images CC BY NC ND