Bunchorntavakul Chalermrat, Chavalitdhamrong Disaya, Tanwandee Tawesak
Chalermrat Bunchorntavakul, Division of Gastroenterology and Hepatology, Department of Internal Medicine, Rajavithi Hospital, College of Medicine, Rangsit University, Bangkok 10400, Thailand.
World J Hepatol. 2013 Sep 27;5(9):496-504. doi: 10.4254/wjh.v5.i9.496.
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.
丙型肝炎病毒6型在东南亚呈地方性流行（在所有丙型肝炎病毒感染中患病率在10%至60%之间），在该地区以外的移民中也有零星报告。由于6型和1b型之间的5'-非翻译区相同，早期基因分型方法对丙型肝炎病毒基因型的诊断可能不准确，因此更倾向于采用核心测序的新型基因分型方法。丙型肝炎病毒6型的危险因素和临床过程与其他基因型没有显著差异。聚乙二醇化干扰素和利巴韦林联合治疗丙型肝炎病毒6型的疗效优于1型，与3型相近，预期持续病毒学应答率为60%至90%。新出现的数据表明，较短疗程的24周治疗与标准的48周治疗同样有效，特别是对于那些在第4周时丙型肝炎病毒RNA检测不到的患者（快速病毒学应答）。此外，用于其他丙型肝炎病毒基因型的应答基线和治疗期预测指标对6型似乎也有效。尽管一些泛基因型直接抗病毒药物已完成II/III期研究（索磷布韦和西米普明），且在少数6型患者中显示出临床益处，但近期在东南亚可能无法广泛获得这些药物。在等待更新疗法的同时，应答指导疗法似乎适用于丙型肝炎病毒6型患者。具有快速病毒学应答的患者（占患者的70%以上）适合24周治疗，预期持续病毒学应答率>80%。没有快速病毒学应答和/或应答预测指标较差的患者可能从48周治疗中获益，第12周时可检测到丙型肝炎病毒RNA（无早期病毒学应答）可作为停药标准。这种治疗方案可能会对丙型肝炎治疗产生重大经济影响，特别是在东南亚，在那里大多数丙型肝炎病毒6型患者的治疗可以安全缩短疗程。
