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Thursday, 8 September 2011

Networks and personalized medicine for better drugs?

For more on this theme see 
- article with Andrew Marsh in the inaugural March 2012 issue of Health Policy and Technology
- article in the October 2011 issue of Public Service Review: Science and Technology Review 

For many individual patients treatments may not exist, may not be very effective, or may result in unpleasant adverse effects. How can prescribers improve drug selection andreduce the harmful effects of medicines? Are there better ways to develop drugs for patients who are difficult to treat?  And what can we do to improve poor adherence to medicines? These elements underpin ‘personalized medicine’, in current use the concept that by considering differences among patients in genetics, disease burden and other factors, more effective and safer drugs can be developed. Personalizing medicine is a path to better disease prevention and control where limited treatment options exist, such as for many cancers, resistant infections and dementia syndromes, and better drug development for new medical challenges. These concepts have in recent years attracted interest from the Royal Society, the Nuffield Council on Bioethics and cognate international institutions.
It is clear that there needs to be consistent investment and support from policy makers and regulators to develop and sustain the academic and industry pharmacology expertise and activity needed for the long-term success of a personalized medicine strategy, so that we can continue to be able to improve the health of the public and individual patients.
NICE is an international leader in developing evidence-based treatment guidelines. Its reports increasingly recognize the need to refine drug choice based on patient characteristics. For example, updated national hypertension guidelines released in August 2011 advise drug selection guided by age, gender, ethnicity, and monitoring, with treatment modified depending on clinical response. NICE also recognizes the need for research on ways, tailored to patient preference, to improve long-term adherence to drug treatment.
Pharmacologists are developing two complementary approaches aimed at achieving “precision medicine” in as many patients as possible: better drug discovery combined with high definition biomarkers for drug selection and monitoring. Network pharmacology brings together sophisticated databases of genetic mechanisms for disease, pharmacological pathways, candidate drugs, and population data describing important variants among individuals in drug handling and responsiveness.  These methods also allow ways to find previously unexpected “off-target” actions of existing or new drugs, which may accelerate discovery of new treatments for serious diseases.
Diagnostic methods are increasingly being used to improve drug selection for individual patients. For example growth tyrosine kinase receptors can be blocked using the biological agent imatinib to treat particular patterns of Philadelphia chromosome-positive chronic myeloid leukaemia, and rare gastro-intestinal tumours. Understanding genes and drugs that influence enzymes that modify drugs in the body, improves accuracy in defining patients who will not respond to a given medicine, or may develop adverse effects.  For example, to minimize risk of serious harm, pharmacogenetic testing is recommended for variability in a specific liver enzyme before deciding whether or not to prescribe the anti-HIV drug abacavir. This knowledge also allows better prediction of a patient’s risk of harm from interactions between treatments, based on recognition of medicines and other remedies that interfere with how drugs are cleared by the body. 

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