Global variation exists for response to Hepatitis therapies

Thu, Jul 2011 04:00pm

In honor of the inaugural WHO World Hepatitis Day 2011, PGENI releases a Global Risk Map for response to Hepatitis therapies. The Hepatitis C virus affects 160 million people worldwide – approximately 2.4% of the world population and is associated with a chronic infection of the liver that results in organ failure or cancer.

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The foundation of treatment of hepatitis C is interferon (often with the medicine ribavirin), which are active in ~60% of patients, but associated with debilitating side effects. Recently a new class of anti-Hepatitis therapies were approved in the USA (protease inhibitors), although most of the world’s infected population will not have access to these medicines for many years due to cost and drug availability. For that reason, it is essential to understand when and where interferon will be active.

Recent studies have found that patients who do not respond to interferon have a different version of part of their genome. Genetic variations in the gene IL28B occur naturally, but can influence the response to interferon therapy for hepatitis C. Patients with the ‘bad’ genotype will only respond30% of the time, compared with 70% response in the ‘good’ gene version. This has important implications for the use of interferon, as the medicine is costly, causes significant side effects, and has to be administered by injection. Knowledge of the risk of interferon failure should be an important part of public health planning for controlling this devastating virus.

Fewer clinical studies have been conducted in developing countries, although they bear a disproportionate burden of disease. Yet, information on the genetic risk of treatment failure can be applied to predict therapeutic success.

The Pharmacogenetics for Every Nation Initiative (www.pgeni.org) works to collect, analyze, utilize, and disseminate information on genetic information to inform the selection of drugs for formularies in developing nations. The release of the 2011 Global Risk Map for response to Hepatitis C therapies on the PGENI website gives guidance for prioritization of interferon therapy and areas where new therapies need to be expedited. For example, a high risk of treatment failure is predicted in central sub-Saharan Africa, where as this same risk is not observed in most Asian countries. There is also a majority of developing countries where there is no data on the risk of interferon treatment failure, weakening the ability to apply these public health principles to improve the control of this virus.

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