The HBV drug entecavir - effects on HIV-1 replication and resistance

Abstract

Entecavir, a drug approved by the Food and Drug Administration for the treatment of chronic hepatitis B virus (HBV) infection, is not believed to inhibit replication of human immunodeficiency virus type 1 (HIV-1) at clinically relevant doses. We observed that entecavir led to a consistent 1-log(10) decrease in HIV-1 RNA in three persons with HIV-1 and HBV coinfection, and we obtained supportive in vitro evidence that entecavir is a potent partial inhibitor of HIV-1 replication. Detailed analysis showed that in one of these patients, entecavir monotherapy led to an accumulation of HIV-1 variants with the lamivudine-resistant mutation, M184V. In vitro experiments showed that M184V confers resistance to entecavir. Until more is known about HIV-1-resistance patterns and their selection by entecavir, caution is needed with the use of entecavir in persons with HIV-1 and HBV coinfection who are not receiving fully suppressive antiretroviral regimens.

Figure 1

Entecavir therapy causes an acute drop in plasma levels of HBV and HIV-1. Viral loads for patients #1 (A), #2 (B), and #3 (C) are shown as a function of time after starting entecavir. Colored bars indicate treatment with entecavir (ETV), tenofovir (TDF), emtricitabine (FTC), efavirenz (EFV), zidovudine (AZT), lamivudine (3TC), and pegylated-interferon alpha-2a (IFN). The AZT and 3TC bars are interrupted to indicate the intermittent nature of this treatment. Dotted lines indicate the limits of detection of the relevant viral loads assays. Open symbols indicate assay values above or below the range of the relevant assays. Time zero values for patient #2 were estimated from the geometric mean of the 3 prior values. The Hepatitis B DNA value 1.2 months before entecavir therapy was used as the time zero value for patient #3.

Figure 2

Entecavir is a potent inhibitor of HIV infection in vitro. (A) Effect of entecavir and zidovudine on infection of primary CD4⁺ T cells in vitro with pseudoviruses carrying pol sequences from the wildtype HIV reference strain NL4-3 (solid lines) or from a wild type clone from patient #1 (dotted lines). Results are expressed as % of maximal infection = (number of infected cells observed in the presence of the indicated concentration of drug/the maximal number of infected cells observed in the absence of a drug effect) × 100. The dotted black line represents a 50% decrease in the number of GFP+ cells. Where they would be obscured by a symbol, error bars are shown at the edge of the symbol. Infection by pseudoviruses carrying Patient #1-derived pol sequence was inhibited by entecavir with an IC₅₀ of ~0.001 μM. Inhibition of infection by zidovudine is also shown for purposes of comparison to entecavir. (B) Effect of entecavir on infection of primary CD4⁺ T cells in vitro with pseudoviruses carrying HIV pol sequences isolated from other patients. Patient #3 is described herein. Patients #139 and #154 have been previously described (13). The dose-response curves were similar for all isolates. The isolate from patient #154 had no drug resistance mutations. The isolate from patient #3 had the non-nucleoside RT inhibitor resistance mutation K103N in RT. The isolate from patient #139 had the V108I and T215D mutations in RT. (C) Dose response curves for wildtype (wt, open symbols) and M184V point mutant (M184V, closed symbols) forms of the reference NL4-3 pseudovirus in the presence of increasing concentrations of entecavir, zidovudine, or lamivudine. The data represent three experiments. (D) Dose response curves for pseudoviruses carrying pol sequences from wild type (wt, open symbols) and M184V mutant (M184V, closed symbols) isolates from patient #1. The experiment was repeated three times with very similar results, and representative data from one experiment are shown. The curves in (A) for wildtype viruses in the presence of entecavir and zidovudine are identical to those in (B) and (C).

Figure 3

Selection for the M184V mutation in HIV-1 RT in a patient on entecavir. (A) Time course of sampling for patient #1. Plasma was obtained for genotypic analysis on the day that entecavir was started (time point 0) and after 2, 4, and 6 months of entecavir monotherapy (time points 1, 2, and 3, respectively). The plasma HIV-1 RNA levels during this period are indicated in the graph. See Figure 1 for full details on the clinical course of patient #1. (B) Fraction of independent plasma virus isolates carrying the M184V mutation at time points 0, 1, 2, and 3. The number of independent clones analyzed was 19, 41, 18, and 27 for time points 0, 1, 2 and 3, respectively. * denotes no resistant mutations detected. (C) Maximum likelihood phylogenetic tree of wild type (open symbols) and M184V mutants (closed symbols) from time points 0, 1, 2, and 3. All isolates from patient #1 cluster together and are clearly distinct (bootstrap value =99) from reference clade B isolates obtained from other patients (HXB2, SF2, RF, and NL4-3)