Top Journal Analysis | Dynamic Changes of HBV RNA in Chronic Hepatitis B Patients on Long-term Nucleoside

Chronic hepatitis B (CHB) infection affects 254 million people worldwide and led to 1.32 million deaths from cirrhosis and hepatocellular carcinoma (HCC) in 2024. Antiviral therapy can reduce the risk of complications, but viral biomarkers are crucial for evaluating treatment efficacy and long-term prognosis. Recently, Professor Mengfeng Yuan's team from Queen Mary Hospital, The University of Hong Kong, published a latest study in Clinical and Molecular Hepatology (IF=14). This study aims to describe the longitudinal changes in HBV RNA in CHB patients receiving five years of nucleos (t)ide analogue (NUC) therapy.

Research Background: HBV RNA is a novel biomarker for chronic hepatitis B (CHB), reflecting the transcriptional activity of covalently closed circular DNA (cccDNA) in the liver. In untreated patients, HBV RNA levels are typically 1–2 log lower than HBV DNA levels. The primary mechanism of nucleos(t)ide analogue (NUC) therapy is to inhibit the reverse transcription of HBV RNA into HBV DNA, leading to an inversion of the RNA-to-DNA ratio after treatment. While most studies have described the early kinetics of HBV RNA during antiviral therapy, the dynamic changes of HBV RNA under long-term NUC treatment remain unclear.

Research Methods: This study included 1,354 CHB patients from Queen Mary Hospital, Hong Kong, aged ≥18 years, and assessed plasma samples from those receiving first-line NUC therapy. The baseline was set at the initiation of NUC treatment (year 0), followed by evaluations at years 1, 3, and 5. The lower limit of detection (LLOD) and quantification (LLOQ) for HBV RNA were 0.8 log U/mL (~20 copies/mL).

Research Results:

A total of 1,354 patients were enrolled. At baseline, the median age was 49.8 years (interquartile range [IQR]: 40.2–57.3 years), with 65.2% being male. The majority (83.9%) were HBeAg-negative, and 28.6% had cirrhosis. The median HBV DNA and HBV RNA levels were 5.76 (IQR: 3.54–7.17) log IU/mL and 3.68 (IQR: 2.42–5.19) log U/mL, respectively.

Table 1. Baseline Characteristics of the Entire Cohort (n=1,354)

Dynamic Changes of HBV RNA and HBV DNA

For HBV DNA, the median levels at years 1, 3, and 5 were 1.00 (IQR: 1.00–2.23), 1.00 (IQR: 1.00–1.00), and 1.00 (IQR: 1.00–1.00) log IU/mL, respectively. The median serum HBV RNA 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 years 1, 3, and 5, respectively (Figure 1).

Figure 1: HBV DNA and HBV RNA Levels at Baseline, Year 1, Year 3, and Year 5 After NUC Treatment

At years 1, 3, and 5, the median decline in HBV RNA levels relative to baseline was 0.82 (IQR: 0.09–1.96) log U/mL, 1.20 (IQR: 0.30–2.30) log U/mL, and 1.54 (IQR: 0.53–2.67) log U/mL, respectively (Figure 2).

Figure 2: Violin Plot Showing the Relative Changes in HBV RNA Levels at Years 1, 3, and 5 Compared to Baseline Under NUC Treatment

Compared to patients treated with entecavir (ETV), those receiving tenofovir (TDF or TAF) showed a significantly smaller decline in HBV RNA levels at years 1 and 3, with statistically significant differences. However, by year 5, there was no significant difference between the groups (Figure 3).

Figure 3: Violin Plot Showing the Relative Changes in HBV RNA Levels at Years 1, 3, and 5 Compared to Baseline Under NUC (ETV, TDF, or TAF) Treatment

After 1, 3, and 5 years of NUC treatment, 69.2%, 88.9%, and 93.0% of patients, respectively, had HBV DNA levels below the detection limit. Correspondingly, the proportions of patients with HBV RNA below the detection limit were 13.5%, 15.9%, and 20.1%, respectively (Figure 4).

Figure 4: Proportion of Patients with Plasma HBV DNA and HBV RNA Below the Detection Limit at Baseline, Year 1, Year 3, and Year 5 After NUC Treatment

Compared to patients treated with entecavir, those receiving tenofovir were more likely to have HBV RNA below the detection limit at year 1 (11.8% vs. 20.7%, p=0.003) and year 3 (14.5% vs. 20.8%, p=0.023), with statistically significant differences (Figure 5).

Figure 5: Proportion of Patients with HBV RNA Below the Detection Limit at Years 1, 3, and 5 After NUC Treatment

At baseline, HBV RNA showed a moderate linear correlation with HBV DNA (r = 0.553, p < 0.001). After NUC treatment, the correlation between HBV RNA and HBV DNA weakened over time.（Year 1: r = 0.257, p < 0.001; Year 3: r = 0.276, p < 0.001; Year 5: r = 0.224, p < 0.001) (Figure 6).

Figure 6: Scatter Plot Showing the Correlation Between HBV RNA and HBV DNA at Different Time Points

Factors Affecting HBV RNA Levels
By analyzing baseline clinical parameters, the study identified subgroups with lower HBV RNA levels. The results showed that subgroups with a higher baseline PAGE-B score had lower HBV RNA levels at all time points. Additionally, cirrhosis was associated with lower HBV RNA levels after 1 year of NUC treatment (Figure 7).

Figure 7: HBV RNA Levels by Cirrhosis and PAGE-B Score Groups at Baseline, Year 1, Year 3, and Year 5 After NUC Treatment

Study Conclusion
During nucleos(t)ide analogue (NUC) therapy, the rate of decline in HBV RNA was much slower than that of HBV DNA, with a median reduction of 1.54 log. After 5 years of first-line NUC treatment, only 16% of patients had plasma HBV RNA levels below the detection limit. This suggests that the majority of patients did not achieve complete silencing of covalently closed circular DNA (cccDNA). Factors such as age, gender, HBeAg status, PAGE-B score, and the duration of NUC treatment were found to influence plasma HBV RNA levels.

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