The dawn of personalised medicines – whereby an individual receives targeted therapy – could be at least 15 to 20 years away because of gaps in our understanding of how genetics relates to the cause of disease, according to a new report from the UK’s Royal Society.

Sir David Weatherall, Chair of the Working Group, commented: “Personalised medicines show promise, but they have undoubtedly been over-hyped. With the human genome sequenced, some people are expecting personalised medicines within a few years, but the reality is still many years away.” Current examples include Roche’s Herceptin (trastuzumab), which is used in cancer patients who score positive for the human epidermal growth factor receptor-2 gene: HER2 is a gene that helps control how cells grow, divide, and repair themselves, and it also directs the production of special proteins, called HER2 receptors. About one out of four breast cancers has too many copies of the HER2 gene or too many receptors.

Personalised medicines, or pharmacogenetics, recognises subsets of common diseases that can be treated differently, the identification of genes that make drugs effective or harmful and the use of differences in susceptibility to infectious diseases to develop new medicines or vaccines. “We need to lay the groundwork now if we are ever to realise the potential of personalised medicines,” added Sir David. “With the NHS expected to spend £11 billion on drugs in 2005-6, there is a need to invest in gathering data on how genes influence drug response in the patient population.”

However, he has also called for investment from both the public and private sectors, and said pharmaceutical companies should receive financial encouragement to develop personalised drugs for what would – essentially – be “relatively small potential markets.” Sir David concluded: “For new drugs, we would like to see better use made of the genetic data collected by pharmaceutical companies in clinical trials. Further private sector input should come from the companies that produce diagnostic DNA tests, [which] will be essential for correctly administering the drugs. Where a drug has been in use for some time and is no longer under patent, the onus will be on the Government to fund or provide incentives for carrying out pharmacogenetic investigations where appropriate.”