title: Loss of HBsAg and antiviral treatment: from basics to clinical significance.
abstract: Accurate prediction of the sustained virological response (SVR) to antiviral therapy against chronic hepatitis B (CHB) is still a crucial problem needing profound investigation. In recent years, quantification of hepatitis B surface antigen (HBsAg), a reliable predictor of SVR and an ideal endpoint of treatment, has attracted increasing attention. Serum HBsAg titer may reflect the level of intrahepatic hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) in most patients, and vary with natural phases of chronic HBV infection, genotypes and variants, antiviral therapy, and other related factors. Serum HBsAg <200 IU/mL or yearly reduction ≥0.5 log10IU/mL may be the optimum cut-off values for prediction of the chance of spontaneous seroclearance of HBsAg. Serum HBsAg <1,000 IU/mL with HBV DNA <2,000 IU/mL may identify most of the inactive HBV carriers from active HBeAg(-) hepatitis. Interferon-based therapy can lead to more significant HBsAg decline than therapy based on nucleoside and/or nucleotide analogues. Different patterns or kinetics of HBsAg decline during therapy are related to different probabilities of SVR. A low HBsAg level, <3,000 IU/mL at baseline, or HBsAg level, <1,500 IU/mL at week 12, or a rapid on-treatment HBsAg decline of ≥0.5 log10IU/mL at week 12, may predict higher probability of SVR. However these cut-off values must be further validated for larger cohort of patients across genotypes worldwide. Incorporation of serum HBsAg level, HBeAg status, HBV DNA load, HBV genotypes, and other related factors might help establish new concept of more practical "response-guided treatment (RGT)" rules for antiviral therapy.
authors.affiliation: Center of Liver Diseases, Bayi Hospital, Nanjing University of Chinese Traditional Medicine, Nanjing, 210002, Jiangsu, China. gslsycy@163.com.
authors.forename: Yuecheng
authors.initials: Y
authors.lastname: Yu
authors.affiliation: Hepatology Unit and Department of Infectious Diseases, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, Guangdong Province, China. jlhou@fimmu.com.
authors.forename: Jinlin
authors.initials: J
authors.lastname: Hou
authors.affiliation: Yamanashi Prefectural Hospital Organization, 1-1-1 Fujimi, Kofu, 400-8506, Yamanashi, Japan.
authors.forename: Masao
authors.initials: M
authors.lastname: Omata
authors.affiliation: National Institute for Viral Disease Control and Prevention, Chinese Center for Diseases Control and Prevention, Beijing, China. euy-tokyo@umin.ac.jp.
authors.forename: Yue
authors.initials: Y
authors.lastname: Wang
authors.affiliation: State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, China. ljli@zju.edu.cn.
authors.forename: Lanjuan
authors.initials: L
authors.lastname: Li
keywords: Chronic hepatitis B; Hepatitis B surface antigen; Interferon; Nucleosides; Nucleotides; Prediction of sustained virological response; Quantification