Minireviews
Copyright ©2013 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Hepatol. Sep 27, 2013; 5(9): 496-504
Published online Sep 27, 2013. doi: 10.4254/wjh.v5.i9.496
Hepatitis C genotype 6: A concise review and response-guided therapy proposal
Chalermrat Bunchorntavakul, Disaya Chavalitdhamrong, Tawesak Tanwandee
Chalermrat Bunchorntavakul, Division of Gastroenterology and Hepatology, Department of Internal Medicine, Rajavithi Hospital, College of Medicine, Rangsit University, Bangkok 10400, Thailand
Disaya Chavalitdhamrong, Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, University of Florida, Gainesville, FL 32610, United States
Tawesak Tanwandee, Division of Gastroenterology and Hepatology, Department of Internal Medicine, Siriraj Hospital, Faculty of Medicine, Mahidol University, Bangkok 10700, Thailand
Author contributions: Bunchorntavakul C conceptualized, researched and reviewed related literature, and drafted this paper; Chavalitdhamrong D and Tanwandee T conceptualized and critically reviewed this paper.
Correspondence to: Chalermrat Bunchorntavakul, MD, Assistant Professor of Medicine, Division of Gastroenterology and Hepatology, Department of Internal Medicine, Rajavithi Hospital, College of Medicine, Rangsit University, Rajavithi Road, Ratchathewi, Bangkok 10400, Thailand. dr.chalermrat@gmail.com
Telephone: +66-2-3548081 Fax: +66-2-3548179
Received: July 8, 2013
Revised: August 5, 2013
Accepted: August 12, 2013
Published online: September 27, 2013
Abstract

Hepatitis C genotype 6 is endemic in Southeast Asia [prevalence varies between 10%-60% among all hepatitis C virus (HCV) infection], as well as also sporadically reported outside the area among immigrations. The diagnosis of HCV genotype can be inaccurate with earlier methods of genotyping due to identical 5’-UTR between genotype 6 and 1b, hence the newer genotyping methods with core sequencing are preferred. Risk factors and clinical course of HCV genotype 6 do not differ considerably from other genotypes. Treatment outcome of HCV genotype 6 with a combination of pegylated interferon and ribavirin is superior to genotype 1, and nearly comparable to genotype 3, with expected sustained virological response (SVR) rates of 60%-90%. Emerging data suggests that a shorter course 24-wk treatment is equally effective as a standard 48-wk treatment, particularly for those patients who attained undetectable HCV RNA at week 4 (RVR). In addition, baseline and on-treatment predictors of response used for other HCV genotypes appear effective with genotype 6. Although some pan-genotypic direct-acting antivirals have completed phase II/III studies (sofosbuvir and simeprevir) with clinical benefit demonstrated in small number of patients with genotype 6, broad availability of these agents in Southeast Asia may not be expected in the near future. While awaiting the newer therapy, response-guided therapy seems appropriate for patients with HCV genotype 6. Patients with RVR (representing > 70% of patients) are suitable for 24-wk treatment with expected SVR rates > 80%. Patients without RVR and/or those with poor response predictors may benefit from 48 wk of therapy, and a detectable HCV RNA at week 12 (with no early virological response) serves as a stopping rule. This treatment scheme is likely to have a major economic impact on HCV therapy, particularly in Southeast Asia, wherein treatment can be truncated securely in the majority of patients with HCV genotype 6.

Keywords: Hepatitis C, Genotype 6, Epidemiology, Southeast Asia, Treatment, Pegylated interferon, Ribavirin, Response-guided therapy

Core tip: Hepatitis C genotype 6 is endemic in Southeast Asia [prevalence varies between 10%-60% among all hepatitis C virus (HCV) infection], as well as also sporadically reported outside the area among immigrations. The diagnosis of HCV genotype can be inaccurate with earlier methods of genotyping due to identical 5’-UTR between genotype 6 and 1b, hence the newer genotyping methods with core sequencing are preferred. Risk factors and clinical course of HCV genotype 6 do not differ considerably from other genotypes. Treatment outcome of HCV genotype 6 with a combination of pegylated interferon and ribavirin is superior to genotype 1, and nearly comparable to genotype 3. Emerging data suggests that a shorter course 24-wk treatment is equally effective as a standard 48-wk treatment, particularly for those patients who attained undetectable HCV RNA at week 4.