Background and aim: Precore (PC) and basal core promoter (BCP) mutations are associated with responses to interferon-based treatment in HBeAg-positive chronic hepatitis B (CHB) patients. Here, we identify viral minority variants in these regions and assess association with response to peginterferon-alfa (Peg-IFN) and adefovir combination therapy.
Patients and methods: Ultra-deep pyrosequencing analysis of the BCP and PC region was performed for 89 CHB patients (42 HBeAg-positive; 47 HBeAg-negative), at baseline and during treatment. Specifically, associations of individual positions with the HBeAg-negative phenotype were studied, as well as the association of the most prevalent mutations with combined response in HBeAg-positive and -negative patients at week 72 (HBeAg negativity, HBV-DNA <2000 IU/mL and ALT normalization at 24 weeks of treatment-free follow-up).
Results: The mutations most strongly correlated with the HBeAg-negative phenotype were at positions 1762/1764 and 1896/1899 in the BCP and PC region, respectively. No major changes in nucleotide composition of these positions were observed during treatment. In HBeAg-negative patients, a combined presence of 1764A and 1896A was correlated with lower ALT levels (p = 0.004), whereas the presence of 1899A was correlated with higher age (p = 0.030), lower HBV-DNA level (p = 0.036), and previous IFN therapy (p = 0.032). The presence of 1764A/1896A or the absence of 1899A at baseline, was associated with lower response rates, after adjustment for HBV genotype (p = 0.031 and p = 0.017) and HBsAg level (p = 0.035 and p = 0.022).
Conclusion: We identified novel correlations between common BCP and PC variants with response to Peg-IFN and adefovir in HBeAg-negative patients. Ultimately, this may guide the selection of those patients most likely to benefit from Peg-IFN-based treatment.
Keywords: Adefovir; Hepatitis B e antigen; Mutation; Peginterferon alfa-2a; Response marker; Ultra-deep pyrosequencing.
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