Cobas 6800 8800 system hbv

The HBsAg levels were measured in in vitro samples and in 50‐fold dilutions of in vivo serum samples using an chemiluminescent enzyme immunoassay (CLEIA; LUMIPULSE Presto HBsAg‐HQ; Fujirebio, Tokyo, Japan; lower limit of detection = 0.005 IU/mL). The hepatitis B e antigen (HBeAg) levels were measured in in vitro samples using CLEIA (LUMIPULSE Presto HBeAg, Fujirebio; lower limit of detection = 1.0 cutoff index). The HBV‐DNA levels were measured using the cobas 6800/8800 system HBV (Roche Diagnostics, Tokyo, Japan; lower limit of detection = 1.0 log IU/mL). The samples were diluted 10‐fold (in vitro experiments) or 100‐fold (in vivo experiments) for analysis.

Blood HBV DNA measurements were performed using the COBAS TaqMan HBV Test, v 2.0 (Roche Diagnostics, K.K. Tokyo, Japan) (~2017/4/2) and COBAS 6800-8800 system HBV (Roche Diagnostics K.K.) (2017/4/3~), which is based on the polymerase reaction assay. The HBV DNA values were measured before the start of treatment, every month for 3 mo after the start of treatment, and every 3 mo thereafter until the completion of treatment. If HBV DNA expression was undetected after treatment, the measurements were continued for 1 year from the completion of treatment. The frequencies at which the HBV DNA value was higher than the detection sensitivity and at which the HBV DNA value was 1.3 Log IU/mL or higher were examined.

The primary end point was the proportion of patients with HBV DNA <10 IU/ml, as determined by real‐time reverse transcriptase PCR assay (COBAS 6800/8800 system HBV) (Roche Molecular Diagnostics, Tokyo, Japan) at week 144 after switching to TAF. We used COBAS TaqMan HBV assay, Version 2.0, to determine the HBV DNA level (the lower limit of quantification: 20 IU/ml) by the end of 2019. This gave us the ability to measure the HBV DNA level of all patients at week 144 with a more sensitive assay than was previously available. Key prespecified secondary end points were the longitudinal change of alanine aminotransferase (ALT), quantitative HBsAg (qHBsAg) level, eGFR, serum phosphate and fasting lipid parameters, including total cholesterol, low‐density lipoprotein cholesterol (LDL‐C), high‐density lipoprotein cholesterol (HDL‐C) and triglycerides. A patient was determined to have ALT normalisation if ALT was less than 35 U/L for men or 25 U/L for women, according to the American Association for the Study of Liver Diseases (AASLD) normal range.²