Longitudinal profile of plasma pregenomic RNA in patients with chronic hepatitis B infection on long-term nucleoside analogues and its interaction with clinical parameters

Background: Plasma pregenomic hepatitis B virus RNA (pgRNA) is a novel biomarker in chronic hepatitis B infection (CHB). We aimed to describe the longitudinal profile of pgRNA and factors influencing its levels in CHB patients on nucleoside analogue (NUC).

Methods: Serial plasma samples from 1354 CHB patients started on first-line NUC were evaluated. Time of NUC initiation was taken as baseline (year 0), followed by 1-year, 3-year and 5-year of NUC therapy. pgRNA was measured by Research Use Only RealTime HBV RNA v2.0 (0.2 mL) (Abbott Diagnostics) with lower limit of detection of 0.8 log U/mL (~20 copies/mL).

Results: Among 1354 subjects (median age at baseline 49.8 (interquartile range [IQR] 40.2-57.3) years, 65.2% male, 16.1% HBeAg-positive, 28.6% cirrhotic), baseline median HBV RNA was 3.68 (IQR 2.42-5.19) log U/mL. Upon NUC therapy, median pgRNA levels were 2.45 (IQR 1.82-3.62), 2.23 (IQR 1.67-3.05) and 2.14 (IQR 1.48-2.86) log U/mL at 1, 3 and 5 years respectively, with the corresponding log U/mL reductions of 0.82, 1.20 and 1.54. Undetectable/ unquantifiable pgRNA was achieved in 13.5%, 15.9% and 20.1% of patients at 1, 3 and 5 years respectively. Older age, male sex, HBeAg-negativity and high PAGE-B score were associated with lower pgRNA.

Conclusion: Plasma pgRNA declines are modest under NUC therapy, with only 16.3% achieving RNA undetectability after 5 years of first-line NUC indicating cccDNA silencing has not been achieved in the majority of patients. Clinical characteristics should be taken into consideration when interpreting the plasma pgRNA level.