Safety and efficacy of adefovir dipivoxil in patients co-infected with HIV-1 and lamivudine-resistant hepatitis B virus: an open-label pilot study

Lancet Sept 1 2001; 358: 718≠23

Y Benhamou, M Bochet, V Thibault, V Calvez, M H Fievet, P Vig, C S Gibbs, C Brosgart, J Fry, H Namini, C Katlama, T Poynard

Summary

Background: Lamivudine-resistant hepatitis B virus (HBV) is found in about 15≠32% of infected patients with or without co-infection with HIV-1 after 1 year of lamivudine therapy. Adefovir dipivoxil is active in vivo and in vitro against wild-type and lamivudine-resistant HBV. We assessed the safety and efficacy of a once daily dose of adefovir dipivoxil in an open-label trial for the treatment of lamivudine-resistant HBV infection in HIV-1-infected patients.

Methods: 35 HIV-1/HBV co-infected patients receiving lamivudine therapy (150 mg twice daily) as part of their current HIV-1 antiretroviral regimen were enrolled. Patients received a 10 mg once-daily dose of adefovir dipivoxil for 48 weeks while maintaining their existing anti-HIV-1 therapy, including lamivudine. Patients were assessed every 4 weeks for safety and efficacy.

Findings: Four patients withdrew from the study (two because of adverse events), leaving 31 patients who received adefovir dipivoxil for a median of 48 weeks (range 44≠48). Mean decreases in serum HBV DNA concentrations from baseline (log 8∑64 copies/mL [SE log 0∑08]) were log 3∑40 copies/mL [log 0∑12] at week 24 (n=31) and log 4∑01 copies/mL [log 0∑17] at week 48 (n=29; p<0∑0001). Two patients underwent hepatitis B e antigen seroconversiončone at week 32 and one at week 36. Adefovir dipivoxil was generally well tolerated, but was associated with a transient increase in serum alanine aminotransferase concentrations in 15 patients. We found no significant changes in either HIV-1 RNA or CD4 cell count.

Interpretation: These results indicate that 48 weeks of 10 mg daily adefovir dipivoxil is well tolerated and active against lamivudine-resistant HBV in HIV-1/HBV co-infected patients.

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Resistance

Among patients with persistent HIV-1 replication at baseline (RNA log 3 copies/mL), no adefovir-dipivoxil-associated resistance mutations were recorded after 12, 24, and 48 weeks of treatment.

Introduction

More than 350 million people, or 5% of the world's population, are chronically infected with hepatitis B virus (HBV). About 10% of those with HIV-1 infection are also carriers of hepatitis B surface antigen (HBsAg).Patients with HIV-1 infection have a higher risk of HBV-related cirrhosis than HIV-1-negative HBV-infected patients, and co-infection with both viruses has been shown to decrease survival in affected individuals.

Lamivudine inhibits HBV replication in more than 80% of infected patients with or without HIV-1 co-infection. However, emergence of HBV resistance to lamivudine has been widely observed in both populations of patients. Resistance is conferred by a mutation in the HBV DNA polymerase gene--ie, substitution of the methionine residue at codon 550 in the YMDD (Tyr-Met-Asp-Asp) motif by either valine (M550V), or isoleucine (M550I). M550V and M550I mutations can be accompanied by a second mutation at codon 526 with the substitution of leucine by methionine (L526M).

HBV resistance to lamivudine is seen in 15-32% of immunocompetent patients after 1 year of continuous therapy. This rate increases to 38%, 49%, and 67% after 2, 3, and 4 years, respectively. Emergence of HBV resistance to lamivudine occurs in 50% and 90% of HIV-1/HBV co-infected patients after 2 and 4 years of therapy, respectively. Patients who develop lamivudine resistance after 1 year of therapy can show some improvement in liver histology compared with baseline measurements. However, the long-term effect of lamivudine resistance on subsequent changes in liver histology is not yet known. Cases of HBV resistance to lamivudine after liver transplantation, resulting in rapid progression to cirrhosis, have been reported. Although liver disease might be related to the host immune response to HBV, in HIV-1/HBV co-infected patients with persistent HBV replication who are receiving highly active antiretroviral therapy (HAART), immune restoration might actually increase progression of liver disease, leading to the rapid development of cirrhosis. An effective in-vivo treatment for lamivudine-resistant HBV strains no longer exists; therefore additional anti-HBV drugs are needed to treat patients with lamivudine-resistant HBV and thereby prevent the progression of liver disease in both HIV-1-positive and HIV-1-negative HBV-infected patients.

Adefovir dipivoxil is a nucleoside analogue with activity against a broad range of viruses, including hepadnaviruses and HIV types 1 and 2. In enzymatic assays, cell culture, and laboratory animals, adefovir dipivoxil is active against human wild-type and lamivudine-resistant HBV strains. To date, none of the described HBV mutations that cause lamivudine and famciclovir resistance have been associated with decreased in-vitro activity of adefovir dipivoxil. In immunocompetent and HIV-1 co-infected patients, adefovir dipivoxil (125 mg daily) was effective for the treatment of wild-type HBV infection. In a phase II placebo-controlled clinical trial,23 patients were given 5, 30, or 60 mg adefovir dipivoxil daily for 12 weeks. The 30 and 60 mg doses had similar efficacies, whereas the 5 mg dose had a less potent anti-HBV activity. However, in a subsequent long-term treatment protocol, chronic dosing over 48 weeks with adefovir dipivoxil at 30 mg resulted in mild, reversible nephrotoxicity (Gilead Sciences, Adefovir dipivoxil investigator's brochure). In ongoing studies, an intermediate 10 mg dose is being explored, since this dose is predicted to be better tolerated than the 30 mg dose during long-term dosing. The first in-vivo evidence of efficacy of the 10 mg daily dose of adefovir dipivoxil against HBV-resistant variants was in five liver-transplant recipients. These individuals had a sustained antiviral response over a mean treatment period of 13 months.24

We did a 48-week, open-label pilot study of the efficacy and safety of a 10 mg daily dose of adefovir dipivoxil in HIV-1-infected patients with lamivudine-resistant HBV.

Results

Patients

Of the cohort of 226 HIV-1-infected HBsAg carriers managed at our centre, 207 were treated with lamivudine. Of these 207 patients, 163 failed prescreening for the study (73 did not have HBV DNA results available 6 months before selection for the study, 66 had undetectable HBV DNA, 11 were co-infected with hepatitis delta virus, two were being treated with interferon alfa, and 11 had poor adherence to anti-HIV-1 therapy). Of the remaining 44 patients, nine did not meet the entry criteria (five had decompensated cirrhosis, one had polycystic renal disease and a serum creatinine concentration of 158 mol/L at screening, one had uncontrolled epilepsy, and two refused to be included). The remaining 35 patients (34 men and one woman, mean age 41∑2 years [SD 9∑1]) were included in the study. Four patients later withdrew from the study: two for adverse events, one for poor compliance, and one for personal reasons. The remaining 31 received adefovir dipivoxil for a median period of 48 weeks. The table summarises the main baseline characteristics, HBV DNA mutations, and HBV genotypes. 23 of the 35 patients had liver biopsies less then 18 months before enrolment. Liver necroinflammatory and fibrosis grades were assessed by the METAVIR scoring system. Five patients had cirrhosis, including two with episodes of liver decompensation with ascites. These two patients had a Child-Pugh score of B8 at baseline; the other three had a score of A5. Two patients were negative for HBeAg but positive for antibodies against HBe (presumed precore mutant). Patients had received lamivudine (150 mg twice daily) for a median of 42∑3 months (range 9≠81). HBV resistance to lamivudine was detected a median of 21∑8 (6≠44) months before receiving adefovir dipivoxil. All patients had detectable serum HBV DNA while on lamivudine therapy at 24 weeks and at 12 weeks before starting adefovir dipivoxil therapy (1583 ng/L and 1632 ng/L, respectively).

3TC Resistance Mutations at Baseline

Efficacy

There was a reduction in serum HBV DNA concentrations in all patients while on adefovir dipivoxil therapy, including in the two patients negative for HbeAg but positive for antibodies against HBe. At baseline, the mean concentration of HBV DNA in serum was log 8∑64 copies/mL (SE log 0∑08). HBV DNA viral load decreased from baseline to week 48. All decreases in HBV DNA were significant at each time point when compared with baseline (p<0∑0001, figure 1). A rebound in serum HBV DNA was seen in all five patients who had temporary (one patient) or permanent (four) discontinuation of adefovir dipivoxil. By week 36, serum HBV DNA concentrations were undetectable by PCR in three patients. In two of these patients, loss of detectable HBV DNA by PCR was followed by a transient acquisition of serum antibodies against HBe. In the other patient, 4 weeks after temporary discontinuation of adefovir dipivoxil for an adverse event, serum HBV DNA rebounded to log 5∑03 copies/mL. Reintroduction of adefovir dipivoxil resulted in a substantial decrease in serum HBV DNA (log 1∑0 copies/mL) after 4 weeks of retreatment. Two patients seroconverted at weeks 32 and 36. These patients remained positive for antibodies to HBe, and had persistently low concentrations of serum HBV DNA until week 48. The two cirrhotic patients with Child-Pugh scores of B8 at baseline improved to A5 by week 24 and remained as A5 at week 48.

Safety

Adefovir dipivoxil was generally well tolerated. None of the patients developed decompensated liver disease. Compared with the baseline concentration (102∑5 IU/L [11∑5]), concentrations of alanine aminotransferase in serum increased from week 8 until week 20, and then declined until week 48 (figure 2). A high degree of variability was seen in concentrations of alanine aminotransferase between patients at each timepoint. 15 patients had transient increases in alanine amino-transferase concentrations in serum of greater than twice the baseline value during the study. The frequency of raised alanine aminotransferase was higher in patients who had a reduction in HBV DNA of greater than log 4 copies/mL by week 48 (nine of 13) than in thwith a reduction BV DNA of less than this amount (six of 19; p=0∑03). None of the 15 patients with transient increases in alanine aminotransferase concentrations had associated clinical symptoms or significant changes in any additional biochemical markers of liver function, including prothrombin time (data not shown). Alanine aminotransferase concentrations declined in all 15 patients 4≠12 weeks after the increases, despite continuation of adefovir dipivoxil therapy.

There were no significant changes in blood-cell count, or mean concentrations in serum of creatinine, phosphate, bicarbonate, amylase, or lipase. Increases in concentrations of serum creatinine of greater than 44 mol/L above baseline, without changes in serum phosphorus concentrations, were seen in two patients. In one patient, creatinine concentration increased by 64 mol/L above baseline at week 28 (grade I toxicity). This patient was receiving concomitant anti-HIV-1 therapy (efavirenz, abacavir, and lamivudine) and had started taking oral aciclovir (200 mg five times daily) 1 week before the creatinine increase. After discontinuation of aciclovir, serum creatinine concentrations returned to normal within 1 week. Adefovir dipivoxil therapy was not interrupted in this patient. In the other patient, an increase in creatinine concentration of 59 mol/L above baseline was seen at week 32 (grade I toxicity). This patient was cirrhotic and was receiving indinavir, stavudine, and lamivudine. Serum creatinine returned to baseline 4 weeks after interruption of adefovir dipivoxil and all antiretroviral drugs. Adefovir dipivoxil was reintroduced at week 36, with a new combination of antiretroviral drugs excluding indinavir (ie, didanosine, stavudine, lamivudine, and lopinavir plus ritonavir). No subsequent increases in serum creatinine were seen thereafter.

An increase in concentrations of glucose in serum and urine was noted in one patient at week 7. This patient, who had a family history of diabetes and who was receiving stavudine and zalcitabine therapy concomitantly, developed diabetes mellitus that required insulin therapy. Another patient withdrew from the study at week 7 owing to insomnia, possibly as a result of adefovir dipivoxil therapy; the insomnia disappeared after discontinuation of adefovir dipivoxil. In these two patients, serum HBV DNA returned to pretreatment concentrations within 4 weeks after discontinuation of adefovir dipivoxil.

Discussion

Despite ongoing lamivudine therapy, patients had raised HBV DNA concentrations that rebounded to prelamivudine levels in the 3≠6 months before enrolment. HBV DNA concentrations decreased rapidly after the commencement of adefovir dipivoxil and continued to decline over 48 weeks of treatment. Anti-HBV efficacy is especially important in HIV-1/HBV co-infected patients since immuno-suppression related to HIV-1 infection intensifies HBV replication.

The kinetics of inhibition of HBV DNA replication were biphasic, with a rapid decrease in the first 2 weeks of treatment (about log 1∑5 copies/mL) and slower but constant reduction thereafter (about log 0∑3 copies/mL per month of treatment).

Prolonged treatment with 10 mg adefovir dipivoxil per day in HIV-1/HBV co-infected patients might be necessary to obtain complete and sustained inhibition of viral replication and HbeAg seroconversion.

The prevalence of lamivudine resistance is related to duration of treatment: 15%, 37%, 49%, and 67% of HIV-1 seronegative patients treated for 1, 2, 3, and 4 years, respectively, develop lamivudine resistance. In HIV-1/HBV co-infected patients, lamivudine resistance accumulates at a rate of 25% per year. Therefore almost all HBV-infected patients chronically treated with lamivudine as maintenance therapy will probably develop resistance at some point. Lamivudine resistance has been associated with the mutations M550V, M550I, L526M, and L526M/M550V in the HBV polymerase gene. The L526M mutation has been reported to confer resistance to lamivudine and famciclovir. In our study, all but one of the patients had the L526 mutation in association with either the M550V or M550I mutation. Adefovir dipivoxil was effective irrespective of the pattern of baseline mutations.

The increase in serum alanine aminotransferase concentrations in 15 patients might be related to activation of the immune response against HBV rather than to hepatotoxicity, as has been seen in HIV-1-infected patients who develop antibodies against HBeAg. Adefovir-dipivoxil-associated hepatotoxicity was difficult to assess in our group of patients because of the many agents they were receiving simultaneously as part of their background antiretroviral drug therapy.

 

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