Background
Treatment including tenofovir disoproxil (TDF) or alafenamide (TAF) is the standard of care in people living with HIV/HBV infection. Serum HBV-RNA is an emerging biomarker reflecting the activity of intrahepatic HBV reservoir.
The aim of the study was to describe HBV seroconversion (HBV-S) rate in HIV/HBV subjects on HBV-active therapy and to analyse markers of HBV activity after achieving HBsAg loss.
Methods
HIV/HBV individuals attending Modena HIV Clinic since 1985 with at least two HBV serology measurements and a follow-up (FU) of at least 6 months were included. Anti-HBV regimens during FU were collected.
HBV-S was defined as HBsAb>10UI/ml in presence of HBsAg loss. HBV-DNA and -RNA were quantified in subjects with HBsAg loss by highly-sensitive assays based on digital droplet PCR (LLOQ: 1IU and 2IU/ml, respectively) at last available FU.
Subjects were compared according to HBV-S using univariate analysis and multivariate logistic regression.
Results
Overall, 163 HBV/HIV subjects were included (77% males, 31% intravenous drug users, HIV and HBV duration of 16 [IQR 9-25] and 10 [IQR 5-19] years, respectively) (Table 1): 32 (20%) had HBsAg loss and 19 (12%) had HBV-S (incident rate: 0.26 per 10,000 PYFU).
HBV-S occurred more frequently if positive HCV-Ab (p=0.004), in liver transplant recipients (p=0.016) and on TDF-based regimen (p=0.013). Individuals without HBV-S had shorter exposure to TAF (p=0.025) and more frequently past AIDS events (p=0.011).
HBV-DNA and –RNA were available for 15(47%) subjects with HBsAg loss (8 with also HBV-S): of those, 12(80%) had residual HBV activity. In detail, 4(33%) had a positivity to both HBV-DNA and -RNA and 8(67%) to HBV-RNA alone. Notably, higher rate of positive HBV-RNA was found in subjects with HBV-S (8/8 [100%] vs 4/7 [57%], p=0.038).
HCV co-infection was associated with HBV-S (adjusted OR 6.4, 95% CI 2.2-19.1, p=0.001), while history of AIDS reduced the probability of HBV-S (aOR 0.1, 95%CI 0.01-0.61, p 0.016). No association with any HBV active regimen was found.
Conclusions
One out of 10 individuals with HIV/HBV co-infection in our cohort reached HBV seroconversion, in line with literature. Previous AIDS-related events did not favour seroconversion, while HCV co-infection seemed to be associated with the outcome.
A residual HBV activity persisted despite HBsAg loss during active HBV therapy: tenofovir discontinuation should be carefully evaluated in those patients and, if pursued, a proper monitoring of HBV markers should not be missed.
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