Data suggest liver experts should take care when prescribing novel antiviral HCV drugs

(Press-News.org) Berlin, Germany, Saturday 02 April 2011: Data presented at the International Liver CongressTM highlight the fact that new novel antiviral compounds for the treatment of hepatitis C virus (HCV) must be prescribed and monitored by experts and specialists to ensure resistance is minimised.1,2,3,4,5,6

Several studies observed the rapid onset of HCV resistance in patients treated with NS3-protease, NS5b-polymerase and NS5a inhibitors. Although these direct anti-virals are effective in both treatment-naive HCV patients and those who've been previously unresponsive to current treatment options, the development of resistant viral variants may cause problems in the future. In fact, two studies found HCV strains resistant to novel antiviral compounds pre-existed in patients who had never previously been exposed to the new antiviral compounds. In these patients, the variants were selected out by treatment.

Professor Heiner Wedemeyer, EASL's Secretary General, said: "While the regulatory approval of these new treatments is a highly anticipated milestone in HCV therapy, these studies show that care must be taken in the prescription and use of the new compounds. What we want to avoid is a rapid spread of HCV resistance within the patient population, which could drastically lower the effectiveness of the new drugs."

The current standard of care for chronic HCV is the combination of pegylated interferon-alfa and ribavirin, but only 40-54% of patients infected with HCV genotype 1 achieve a sustained virological response (SVR).7,8 Novel antiviral therapeutics are much sought after to treat patients who don't respond to the current standard of care. As such, a large number of new drugs for HCV are at various stages of preclinical and clinical development.9

However, as each new copy of the HCV genome exhibits on average one nucleotide change per replication cycle, HCV's replication machinery allows the virus to quickly come up with mutations that render it resistant to antiviral drugs. This is a major concern for successful anti-HCV therapy.10

NS3 protease inhibitors block the function of the HCV NS3 protease, an enzyme essential for HCV's replication. NS5A replication complex inhibitors block the function of HCV nonstructural protein 5A, a multifunctional protein essential for HCV replication.10

### Notes to Editors

About EASL EASL is the leading European scientific society involved in promoting research and education in hepatology. EASL attracts the foremost hepatology experts and has an impressive track record in promoting research in liver disease, supporting wider education and promoting changes in European liver policy.

EASL's main focus on education and research is delivered through numerous events and initiatives, including: The International Liver CongressTM which is the main scientific and professional event in hepatology worldwide Meetings including Monothematic and Special conferences, Post Graduate courses and other endorsed meetings that take place throughout the year Clinical and Basic Schools of Hepatology, a series of events covering different aspects in the field of hepatology Journal of Hepatology published monthly Participation in a number of policy initiatives at European level

About The International Liver CongressTM 2011 The International Liver Congress™ 2011, the 46th annual meeting of the European Association for the study of the Liver, is being held at the Internationales Congress Centrum, Berlin, Germany from March 30 – April 3, 2011. The congress annually attracts over 7,500 clinicians and scientists from around the world and provides an opportunity to hear the latest research, perspectives and treatments of liver disease from principal experts in the field.

References 1. McPhee F et al. Charactarizaion of virologic escape in HCV gentotype 1 null responders receiving a combination of the NS3 protease inhibitor BMS-650032 and NS5A inhibitor BMS-790052. Abstract presented at The International Liver CongressTM 2011

2. Chevaliez S et a. Molecular characterization of HCV resistance to telaprevir by means of ultra-deep pyrosequencing: pre-existing resistant variants and dynamics of resistant populations. Abstract presented at The International Liver CongressTM 2011

3. Hebner C et al. Emergence and persistence of ns5b mutations following combination treatment with tegobuvir (gs-9190) plus standard of care--long-term follow-up from the phase iib study gs-us-196-0103. Abstract presented at The International Liver CongressTM 2011

4. Zeuzem S et al. Boceprevir Resistance-Associated Variants (RAVs) are observed more frequently in HCV (gt1)-infected Patients with poor response to peginterferon alfa- 2B/ribavirin. Abstract presented at The International Liver CongressTM 2011 (1621)

5. Svarovskaia E et al. Abundant minority drug-resistant ns3 mutants detected by deep sequencing in hcv patients as early as 24 hours after initiating antiviral treatment. Abstract presented at the international liver congresstm 2011 (1773)

6. Sullivan J et al. Evolution of Treatment-Emergent Resistant Variants in Telaprevir Phase 3 Clinical Trials. (1783)

7. Fried M.W et al. "Peginterferon alfa-2a plus ribavirin for chronic hepatitis C virus infection." New England Journal of Medicine 347.13 (2002): 975-82 8. Hadziyannis S J et al. "Peginterferon-alpha 2a and ribavirin combination therapy in chronic hepatitis C - A randomized study of treatment duration and ribavirin dose." Annals of Internal Medicine 140.5 (2004): 346-55.

9. Shiffman M L. "Treatment of hepatits C in 2011:what can we expect?" Curr.Gastroenterol.Rep. 12 (2010): 70-75

10. Raffaele De Francesco and Giovanni Migliaccio (2005). Challenges and successes in developing new therapies for hepatitis C. Nature, 436, 953-960