Entecavir, an antiviral proven superior to lamivudine in individuals infected only with hepatitis B virus (HBV), lowered HBV viral load in people coinfected with HBV and HIV, according to new research. One third of study participants taking entecavir reached a normal alanine aminotransferase (ALT) level in 24 weeks, reported Dr. Pessoa from Sao Paulo’s Emilio Ribas Infection Institute at the 12th Conference on Retroviruses and Opportunistic Infections held in Boston, Massachusetts.
Unlike 3 anti-HBV drugs used in coinfected people—lamivudine, adefovir, and tenofovir—entecavir has no activity against HIV and so does not promote evolution of HIV-resistant virus. Research shows no interaction between entecavir and these other three agents. Moreover, entecavir does not affect liver enzymes involved in metabolising protease inhibitors and nonnucleoside reverse transcriptase inhibitors.
The international trial enrolled 68 HBV/HIV-coinfected people already taking lamivudine. Researchers randomised 51 enrollees to 24 weeks of entecavir (1mg once daily) and 17 to take placebo, while continuing lamivudine. All study participants had detectable HBV viremia, and 88% had one or more lamivudine-related mutations.
The predominantly white and male study group began treatment with an average HBV viral load just above 9 log10 copies/mL. After 24 weeks the mean HBV viral load fell 3.66 log10 copies/mL with entecavir while rising 0.11 log10 copies/mL in the placebo group, a highly significant difference in an on-treatment analysis (P
Among individuals assigned to receive entecavir, 84% had an HBV viral load below 400 copies/mL or at least a 2 log (100-fold) HBV viral load drop from baseline after 24 weeks of treatment.
While 47% of patients taking entecavir reached an ALT level below 1.25 times the upper limit of normal, only 17% taking placebo did so. ALT readings fell below the upper limit of normal in 34% taking entecavir and 8% taking placebo, a difference that approached statistical significance (P = .08).
Laboratory abnormalities proved equivalent with entecavir and placebo, and only one person taking entecavir had serious complications: hepatic encephalopathy and esophageal varices judged to be unrelated to treatment.
Entecavir had no effect on HIV-1 viral load or CD4+ cell count, which averaged 2.15 log10 copies/mL and 508 cells/mm3 at study entry, respectively.
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Pessoa W et al. Entecavir in HIV/HBV-co-infected patients: safety and efficacy in a phase II study (ETV-038). Twelfth Conference on Retroviruses and Opportunistic Infections, Boston, abstract 123, 2005.