HBV RNA is a predictive marker for HBeAg loss during antiviral treatment with nucleoside/nucleotide analogues in patients with chronic hepatitis B virus (HBV) infection

Aims: Treatment with NUCs can completely suppress HBV DNA levels in most patients, however there are few markers for the prediction of long term response. Circulating HBV mRNA particles can be detected in the serum (Su et al., 2001). We studied the association of treatment response with serum levels of full-length (fl) and truncated (tr)HBV mRNA.

Methods: For specific detection and quantification of fl and trRNA species, two step real-time reverse transcription PCRs were developed (detection limit 450 and 600 copies/mL, respectively). Plasmid based positive controls and internal controls were generated for the assays. 67 patients (mean age 45±12.2[range, 18–74] years, 41 male, 45 HBeAg positive, 36 HBV genotype D, mean HBV DNA level 7.6±8[9–2.8] log10copies/mL) receiving either tenofovir (TDF) 300mg/day (n=34) or lamivudine (LAM) 100mg/day (n=33) were retrospectively analyzed. Inclusion criteria were treatment duration >24 months and availability of serum samples stored at –20°C representing the start and months 3, 6, 9, 12, and 24 of treatment. HBV DNA levels were measured by COBAS TaqMan HBV (Roche, detection limit 35 copies/mL). HBs-antigen levels were measured by Abbott Architect assay.

Results: Overall, at treatment months 0, 12, and 24 the mean fl and trRNA levels were 6.7±7.3 [8–2.6], 6.5±7 [7.9–2.6] and 5.9±6.5 [7.2–2.6], and 7.1±7.7 [8.5–2.7], 5.8±6.2 [7–2.7] and 5.1±5.5 [6.2–2.7]. Levels of mRNA did not correlate with HBsAg levels. Starting at month 3, patients receiving TDF showed a significantly stronger decrease in HBV DNA levels compared to patients receiving LAM (p=0.02), however there were no differences in fl, trRNA or HBsAg levels (p=n.s.). In patients remaining HBeAg positive (n=30) flRNA levels remained unchanged until month 12, however in patients who achieved HBeAg loss (n=15) flRNA were already lower at baseline (p=0.02) and decreased at months 3, 6, 9 and 12 (p<0.0001). HBV DNA and HBsAg levels showed no differences (p=n.s.). In 4 patients achieving HBsAg loss between month 7–24, fl and trRNA levels already became undetectable until month 5.

Conclusion: HBV RNA levels represent a strong predictor of HBeAg loss during treatment with NUCs. The value of this novel marker needs to be refined in future studies.