Hepatitis B therapy: the plot thickens

Hepatitis B virus Quantification and Detection of YMDD Mutants in a Single Reaction by Real-Time PCR and Annealing Curve Analysis

Background

Long-term antiviral therapy, although effective for treatment of hepatitis B, might select the emergence of drug-resistant hepatitis B virus (HBV) mutants. Detection of HBV mutants and determination of viral titre are two crucial parameters for monitoring treatment response and occurrence of mutants. In this study, we take lamivudine resistance as an example to develop a method that can determine both parameters in a single-tube PCR reaction.

Methods

The method contained two consecutive steps: in the first step, real-time PCR was used for quantification; in the second step, a novel annealing curve analysis was used for detecting YMDD mutants. For accurate quantification, PCR primers and hybridization probes were chosen from highly conserved regions to ensure the equivalent amplification of all HBV genotypes. Within the sensor probe, there were signature nucleotide polymorphisms that could effectively differentiate YMDD mutants from wild type by distinct melting temperatures (Tm) values. The clinical applicability of the assay was tested in serial samples from 90 patients receiving lamivudine treatment.

Results

This assay could readily differentiate YMDD, YIDD and YVDD mutants by their distinct Tm values. The quantification results showed great consistency in a linear range from 103 to 1011 copies/ml. Moreover, this assay could detect YMDD mutants accounting for ≤10% of the total viral population. Its clinical feasibility has been verified in primary specimens.

Conclusions

The newly designed YMDD detection method is simple, sensitive, cost-effective, time-saving and provides a useful tool for follow-up of patients treated with lamivudine or other antiviral drugs.

The current management of HBV drug resistance

Lamivudine and adefovir have potent inhibitory effects on hepatitis B virus (HBV) replication. Although short-term therapy is feasible in a selected subgroup of patients, prolonged therapy is required for sustained suppression in the majority of patients. However, HBV species with mutations in the tyrosine-methionine-aspartate-aspartate (YMDD) locus of the HBV RNA-dependent DNA polymerase (rtM204 I/V) conferring resistance to lamivudine may emerge after 9-10 months therapy. The incidence increases with duration of therapy up to 70% after 5 years lamivudine therapy. Serum alanine aminotransferase (ALT) elevation and HBV DNA rebound ( I log) occur in >90% of the patients with rtM204 I/V during continued lamivudine therapy. Marked flare of serum ALT may occur, sometimes severe, and may be complicated with decompensation or even fatality. The initial clinical and histologic improvement may also reverse after emergence of rtM204 IN Studies do suggest that stopping seems better than continuing lamivudine therapy. Limited data show that interferon therapy seems ineffective. Add-on adefovir therapy is effective in suppressing rtM204 I/V in both compensated and decompensated patients. Switching to adefovir monotherapy is effective and safe even in cirrhotic patients with decompensation. The overall incidence of adefovirresistant rtN236T and A181V is low, being 0 after one year and 5.9% after 3 years' therapy. The impact of adefovir resistance is less clear but is responsive to lamivudine therapy. In conclusion, monitoring of viral breakthrough to start effective intervention is mandatory during direct antiviral therapy.

High rates of progressive hepatic functional deterioration whether lamivudine therapy is continued or discontinued after emergence of a lamivudine-resistant mutant: a prospective randomized controlled study

BACKGROUND

The management of patients with lamivudine-resistant mutants remains challenging, and no clear evidence has been presented concerning the discontinuation of lamivudine.

METHODS

Seventy-four patients with lamivudine-resistant mutants were prospectively enrolled and randomized; 37 patients continued (group A) and 37 patients discontinued lamivudine therapy (group B). The median follow-up was 20 months.

RESULTS

Serum albumin levels were reduced and prothrombin time was prolonged in both groups versus baseline (P = 0.015 and 0.045, respectively). Four patients in group A (10.8%) and six in group B (16.2%) experienced hepatitis flare, but the difference was not significant (P > 0.05). Multivariate analyses identified a younger age as a risk factor for hepatitis flare (P = 0.021). Seven (18.9%) decompensations occurred in group A and five (13.5%) in group B, which was not a significant difference (P > 0.05). Multivariate analyses revealed higher alanine aminotransferase and a lower platelet count as risk factors for hepatic decompensation (P = 0.001 and 0.001, respectively). The patients whose platelet count was <65 000/microl experienced hepatic decompensations more frequently (50%) than those with platelet counts >65 000/microl (13.2%) during follow-up (P = 0.05).

CONCLUSIONS

The clinical course of group B was not significantly different from that of group A. Therefore, the discontinuation of lamivudine may be a feasible option when other antiviral agents active against lamivudine-resistant mutants are unavailable.

Lamivudine treatment in maternally transmitted chronic hepatitis B virus infection patients

BACKGROUND

Lamivudine treatment in chronic carriers who acquired hepatitis B virus through maternal transmission were investigated.

METHODS

A total of 29 subjects (Male:Female, 24:5; mean age, 14.7 +/- 5.6 years) who were hepatitis B e antigen (HBeAg) seropositive for >6 months, alanine aminotransferase (ALT) was >1.3 times of upper limit of normal value, and receiving a 52 week-long treatment, received open-label lamivudine (3 mg/kg per day, maximum 100 mg/day). Another 29 subjects matched for gender, age, liver function, and HBeAg status followed up before the introduction of lamivudine served as the control group. The control group did not receive any treatment and were evaluated at week 52 after the onset of abnormal ALT. Mothers of all study subjects were hepatitis B surface antigen (HBsAg) carriers. A successful treatment response at week 52 was defined as: (i) undetectable hepatitis B virus DNA by real time polymerase chain reaction; (ii) normal ALT; and (iii) HBeAg/anti-HBe seroconversion. Lamivudine-resistant YMDD mutants were checked at week 52.

RESULTS

The lamivudine group did not reach a better successful treatment response rate than the control group (17 vs 10%, P = 0.44), except in patients with a baseline ALT >5 times of the upper limit of normal value. YMDD mutants developed in 34% of patients in the lamivudine group.

CONCLUSION

Lamivudine treatment is effective for maternally transmitted subjects with high ALT.

Transformation of hepatitis B serologic markers in babies born to hepatitis B surface antigen positive mothers

AIM: To better understand the clinical significance of hepatitis B serologic markers in babies born to hepatitis B surface antigen (HBsAg) positive mothers, the incidence of maternal serologic markers of hepatitis B via placenta and its transformation in these babies were investigated.

METHODS: Mothers with positive HBsAg were selected in the third trimester of pregnancy. Their babies received immunoprophylaxis with hepatitis B immunoglobulin and hepatitis B vaccine after birth, and were consecutively followed up for hepatitis B serologic markers and HBV DNA at birth, mo 1, 4, 7, 12, and 24.

RESULTS: Forty-two babies entered the study, including 16 born to hepatitis B e antigen (HBeAg)-positive HBsAg carrier mothers and 26 to HBeAg-negative HBsAg carrier mothers. Apart from four babies born to HBeAg-positive carrier mothers and demonstrated persistent positive HBeAg eventually became HBV carriers, all other babies developed anti-HBs before 12 mo of age. Among the other 12 babies born to HBeAg-positive carrier mothers, HBeAg was detected in 7 at birth, in 4 at mo 1, and in none of them thereafter. No antibody response to the transplacental HBeAg was detected. Among the babies born to HBeAg-negative carrier mothers, anti-HBe was detected 100% at birth and mo 1, in 88.5% at mo 4, in 46.2% at mo 7, in 4.2% at mo 12 and none in mo 24. Among all the immunoprophylaxis-protected babies born to either HBeAg-positive or HBeAg-negative carrier mothers, anti-HBc was detected in 100% at birth, mo 1 and mo 4, in 78.9% at mo 7, in 36.1% at mo 12 and in none at mo 24.

CONCLUSION: HBeAg can pass through human placenta from mother to fetus and become undetectable before 4 mo of age, but no antibodies response to the transplacental HBeAg can be detected till mo 24 in the immunoprophylaxis-protected babies. The sole existence of anti-HBe before 1 year of age or anti-HBc before 2 years of age in babies born to HBsAg carrier mothers may simply represent the transplacental maternal antibodies, instead of indicators of HBV infection status.

Clinical emergence of entecavir-resistant hepatitis B virus requires additional substitutions in virus already resistant to Lamivudine

Entecavir (ETV) exhibits potent antiviral activity in patients chronically infected with wild-type or lamivudine (3TC)-resistant (3TC(r)) hepatitis B virus (HBV). Among the patients treated in phase II ETV clinical trials, two patients for whom previous therapies had failed exhibited virologic breakthrough while on ETV. Isolates from these patients (arbitrarily designated patients A and B) were analyzed genotypically for emergent substitutions in HBV reverse transcriptase (RT) and phenotypically for reduced susceptibility in cultures and in HBV polymerase assays. After 54 weeks of 3TC therapy, patient A (AI463901-A) received 0.5 mg of ETV for 52 weeks followed by a combination of ETV and 100 mg of 3TC for 89 weeks. Viral rebound occurred at 133 weeks after ETV was started. The 3TC(r) RT substitutions rtV173L, rtL180M, and rtM204V were present at study entry, and the additional substitutions rtI169T and rtM250V emerged during ETV-3TC combination treatment. Reduced ETV susceptibility in vitro required the rtM250V substitution in addition to the 3TC(r) substitutions. For liver transplant patient B (AI463015-B), previous famciclovir, ganciclovir, foscarnet, and 3TC therapies had failed, and RT changes rtS78S/T, rtV173L, rtL180M, rtT184S, and rtM204V were present at study entry. Viral rebound occurred after 76 weeks of therapy with ETV at 1.0 mg, with the emergence of rtT184G, rtI169T, and rtS202I substitutions within the preexisting 3TC(r) background. Reduced susceptibility in vitro was highest when both the rtT184G and the rtS202I changes were combined with the 3TC(r) substitutions. In summary, infrequent ETV resistance can emerge during prolonged therapy, with selection of additional RT substitutions within a 3TC(r) HBV background, leading to reduced ETV susceptibility and treatment failure.

Hepatitis B virus variants in an HIV-HBV co-infected patient at different periods of antiretroviral treatment with and without lamivudine

Background

Lamivudine inhibits replication of both human immunodeficiency virus (HIV) and hepatitis B virus (HBV) and is commonly used as part of antiretroviral therapy. The main limitation in the use of lamivudine is resistant mutation selection. Most of these mutations affect the YMDD motif of the HBV DNA polymerase. The resistance occurs through M550V or M550I aminoacid replacements. The M550V variation may be accompanied by L526M mutation, notably in HIV-HBV co-infected patients. The aim of this study was to investigate mutations associated with lamivudine resistance in a hemodialysis patient chronically co-infected with HIV-1 and HBV, who was submitted to several antiretroviral treatments.

Methods

HBV isolates derived from three blood samples collected at different times of antiretroviral therapies with and without lamivudine, were titred and submitted to nucleotide sequencing.

Results

HBV isolate derived from a sample collected in 1999 during an antiretroviral treatment with lamivudine showed the lamivudine resistant double mutation (L526M, M550V). However, no mutation associated with lamivudine resistance was observed in the HBV genome derived from the sample collected during a period of treatment without lamivudine (2001). After reinstitution of lamivudine (2002), the predominant HBV population exhibited a rare triple mutation (V519L, L526M, M550V), which has previously been associated with an in vitro reduction of virus antigenicity (escape mutant). HBV DNA was detected at high levels (10⁸–10⁹ copies/ml) in the three blood samples.

Conclusions

Reintroduction of lamivudine as part of antiretroviral treatment in a patient who had developed lamivudine resistant HBV strains favored the predominance of an HBV isolate with reduced antigenicity. The absence of hepatitis acute exacerbation in this patient may be correlated to the absence of significant variations of the viral load, which was independent of the presence of mutations in the HBV DNA polymerase.

Fatal liver failure due to reactivation of lamivudine-resistant HBV mutant

We report a case of fatal liver failure due to reactivation of lamivudine-resistant HBV. A 53-year-old man was followed since 1998 for HBV-related chronic hepatitis. Serum HBV-DNA was 150 MEq/mL (branched DNA signal amplification assay) and ALT levels fluctuated between 50-200 IU/L with no clinical signs of liver cirrhosis. Lamivudine (100 mg/d) was started in May 2001 and serum HBV-DNA subsequently decreased below undetectable levels. In May 2002, serum HBV-DNA had increased to 410 MEq/mL, along with ALT flare (226 IU/L). The YMDD motif in the DNA polymerase gene had been replaced by YIDD. Lamivudine was continued and ALT spontaneously decreased to the former levels. On Oct 3 the patient presenting with general fatigue, nausea and jaundice was admitted to our hospital. The laboratory data revealed HBV reactivation and liver failure (ALT: 1828 IU/L, total bilirubin: 10 mg/dL, and prothrombin INR: 3.24). For religious reasons, the patient and his family refused blood transfusion, plasma exchange and liver transplantation. The patient died 10 d after admission. The autopsy revealed remarkable liver atrophy.

No Benefit to Continue Lamivudine Therapy after Emergence of Ymdd Mutations

Background

Mutations in the sequence of the conserved tyrosine-methionine-aspartate-aspartate (YMDD) locus of the HBV RNA-dependent DNA polymerase (rt M 204 I/V) may develop after 6–9 months of lamivudine therapy. The current practice of continuing lamivudine therapy has been associated with hepatitis flares or even hepatic decompensation. In addition, experiments have shown that the defective replication competency of rt M 204 I/V restores upon addition of lamivudine.

Aim

To evaluate whether continuing lamivudine therapy after emergence of rt M 204 I/V is appropriate.

Patients and methods

The clinical courses of 66 patients with continuing lamivudine therapy (continued group) and 68 patients who discontinued lamivudine therapy (discontinued group) were monitored monthly or more frequently if condition required. Hepatitis flare, jaundice, hepatic decompensation and hepatitis B e antigen (HBeAg) seroconversion in HBeAg-positive patients were documented as events.

Results

In a 12-month period, hepatitis flares and decompensations occurred in 67 and 11%, respectively, in patients who continued lamivudine therapy, as compared with 54 and 7%, respectively ( P>0.05), in those who stopped therapy. HBeAg seroconversion rate was 19% in continued group and 35% in discontinued group ( P=0.08). Serum HBV DNA increased in 48 (73%) of the continued group, and the median level increased from 46 pg/ml upon first detection of mutation to 330 pg/ml ( P<0.001) at the end of 12 months continuing therapy. In contrast, serum HBV DNA level in the discontinued group increased in 22 (33%) patients but decreased in 39 patients, and median level decreased from 172 to 55 pg/ml at the end of 12 months after stopping lamivudine.

Conclusion

These results suggest that there is no benefit to continued lamivudine therapy after emergence of rt M 204 I/V. Presented in part at the Digestive Disease Week, San Francisco, Calif., USA, May 2002.

Clinical outcome and virologic profiles of severe hepatitis B exacerbation due to YMDD mutations

BACKGROUND/AIMS

To study the outcome and the virologic profiles of severe hepatitis exacerbations due to YMDD mutants in lamivudine-treated patients.

METHODS

Eighteen lamivudine-treated patients with severe hepatitis exacerbations due to YMDD mutants were recruited. Laboratory and clinical parameters were monitored. Viral genotypes and YMDD mutations were determined.

RESULTS

None of the 18 patients had YMDD wild-type during exacerbations. Three (17%) and 15 (83%) patients had genotypes B and C, respectively. Elevated bilirubin levels and prolonged prothrombin time were found in 11 (61%) and six patients (33%) respectively. Three patients (17%) had adverse outcome with the development of ascites and/or encephalopathy. One of these patients required liver transplantation and one died. Both patients had evidence of cirrhosis before treatment and hepatitis B e antigen (HBeAg) seroreversion from anti-HBe positivity. The remaining 16 patients (89%) have no evidence of pre-existing cirrhosis. Thirty seven percent of patients had normal alanine aminotransferase levels at the last follow-up. The median HBV DNA level at the last follow-up was significantly lower than the pre-treatment level (P=0.009).

CONCLUSIONS

Though the majority of patients with severe hepatitis exacerbations due to YMDD mutants had uneventful course, early liver transplantation should be considered in patients with pre-existing cirrhosis and HBeAg seroreversion.

Long-term outcomes of thymosin-alpha 1 and interferon alpha-2b combination therapy in patients with hepatitis B e antigen (HBeAg) negative chronic hepatitis B

Hepatitis B e antibody (HbeAb) and hepatitis B virus (HBV) DNA positive chronic hepatitis is a clinical entity, distinct from classical hepatitis B e antigen (HbeAg) positive chronic hepatitis B. Our aim was to evaluate the long-term therapeutic efficacy of the combination of interferon alpha-2b and thymosin-alpha1 compared with lamivudine plus interferon alpha-2b and interferon alpha-2b alone. Fifty-two patients with HbeAg-negative chronic hepatitis B were assigned to three different groups in a nonrandomized manner. Group 1 (n = 27) received thymosin-alpha1 [1.6 mg subcutaneously (sc), twice a week] and interferon alpha-2b (10 MIU sc, three times per week) for 26 weeks, subsequently followed by interferon alpha-2b monotherapy at the same dosage for an additional 26 weeks. Group 2 (n = 10) received interferon alpha-2b (10 MIU sc, three times per week) for 52 weeks. Group 3 (n = 15) received interferon alpha-2b (10 MIU sc, three times per week) and lamivudine [100 mg orally (po), q.d.] for 52 weeks, followed by continuous lamivudine (100 mg po, q.d.) therapy. By the end of 78 weeks, a sustained response (SR-6 mo) was seen in 74% (20/27) of the patients within Group 1. On the contrary, Groups 2 and 3 had sustained response rates of 40 (4/10) and 53.3% (8/15), respectively (p = 0.13). At the end of 12 months post-treatment in Group 1, a virological and biochemical response rate was seen in 70.3% of patients (19/27); in contrast, Groups 2 and 3 had response rates of 20 (2/10) and 26.6% (4/15), respectively (p = 0036). At the end of the 18-month post-treatment follow-up period, 71.4% (19/27) of patients in Group 1, 10% of patients in Group 2 (1/10), and 20% of patients in Group 3(3/15) preserved their sustained response (p = 0.0003). Interferon alpha-2b and thymosin-alpha1 combination therapy results in significant virological and biochemical response rates compared with standard therapeutic regimens and is well tolerated.

Management of YMDD mutations during lamivudine therapy in patients with chronic hepatitis B

Lamivudine is a nuleoside analog with potent inhibitory effects on hepatitis B virus (HBV) replication. Prolonged therapy is required for sustained suppression. However, HBV species with mutations in the tyrosine-methionine-aspartate-aspartate (YMDD) locus of the HBV-RNA-dependent DNA polymerase confering resistance to lamivudine may emerge after 6-9 months therapy with an incidence of 38% and 67% after 2 and 4 years of lamivudine therapy, respectively. During continued lamivudine therapy, patients with YMDD mutant HBV usually show serum alanine aminotransferase (ALT) and HBV-DNA elevations at lower median levels than their baseline. Marked flare of serum ALT or acute exacerbation may occurred as the results of cytotoxic T lymphocyte mediated immune response directed against YMDD mutant. Although viral clearance with or without emergence of distinct lamivudine resistant mutants may occur after such exacerbations, 20% of the exacerbations are complicated with decompensation or even fatality. The exacerbations appear to be more severe than those occur during the natural course of wild type HBV chronic infection. The current practice of continuing lamivudine therapy, therefore, requires careful evaluation. Alternatives include interferon therapy but this seems ineffective. Adefovir dipivoxil and entecavir may effectively suppress the YMDD mutant but these treatments have not yet been available for use. Recent studies have shown no benefit to continuing lamivudine therapy in patients with YMDD mutantions. Before a rescue drug becomes available, the most cost-effective strategy is to select patients with stronger endogenous anti-HBV immunity to increase efficacy and to shorten the duration of lamivudine therapy to avoid the emergence of YMDD mutations.

Outcome of anti-HBe positive chronic hepatitis B in alpha-interferon treated and untreated patients: a long term cohort study

BACKGROUND/AIMS

We studied the influence of biochemical and virologic patterns and interferon on the outcome of anti-HBe positive chronic hepatitis B in 164 (103 treated) consecutive patients, followed-up prospectively for a mean of 6 years (21 months-12 years).

METHODS

Histology, biochemical and virologic profiles were characterized by monthly monitoring during the first 12 months of follow-up. Thereafter patients underwent blood and clinical controls every 4 and 6 months, respectively. Cirrhosis at follow-up histology or end stage complications of cirrhosis served as end points for the analysis of factors influencing disease progression in patients with baseline chronic hepatitis or cirrhosis, respectively.

RESULTS

Disease progression was associated with older age (P<0.001), absence of previous HBeAg history (P=0.017) and higher serum HBV-DNA levels (P=0.009) (more frequently observed in unremitting disease profile, P=0.012) at multivariate analysis. Fluctuations of IgM anti-HBc levels (associated with disease exacerbations, P=0.045) correlated with end stage complications in cirrhotics (P=0.011). Disease improved in 14.6 and 1.6% of treated and untreated patients, respectively (P=0.015): interferon slowed disease progression (P<0.001).

CONCLUSIONS

The outcome of anti-HBe positive chronic hepatitis B is worsened by older age and persistent viral replication or hepatitis exacerbations in chronic hepatitis or in cirrhotic patients, respectively. Interferon reduces by 2.5-folds disease progression.

Induction of cytotoxic T lymphocyte responses against hepatitis delta virus antigens which protect against tumor formation in mice

The cellular immune response is a crucial defense mechanism against hepatotropic viruses and in chronic viral hepatitis prevention. Moreover, hepatitis delta virus (HDV) immunogenicity may be an important component in the development of prophylactic and therapeutic vaccines. Therefore, we evaluated the immunogenicity of the small (HDAg) or large delta antigen (LHDAg) to be used as a DNA-based vaccine. We immunized different mouse haplotypes, determined cellular immune responses, and tested protection of animals against tumor formation using syngeneic tumor cells stably expressing the delta antigens. Both LHDAg and HDAg primed CD4+ and CD8+ T cell immunity against both forms of delta antigens. CD8+ T cell frequencies were about 1% and antigen-specific CD8+ T cells remained detectable directly ex vivo for at least 35 days post-injection. No anti-delta antibody responses could be detected despite multiple detection systems and varied immunization approaches. We observed protection against syngeneic tumor formation and growth in mice immunized with DNA plasmids encoding secreted or intracellular forms of HDAg and LHDAg but not with recombinant HDAg establishing the generation of significant cellular immunity in vivo. Both CD4+ and CD8+ T cells were required for antitumoral activity as determined by in vivo T cell depletion experiments. The results indicate that DNA-based immunization with genes encoding LHDAg and HDAg induces strong T cell responses and, therefore, is an attractive approach for the construction of therapeutic and prophylactic T cell vaccines against HDV.

[Diagnosis and treatment of hepatitis B]

Hepatitis B constitutes a serious public health problem. It has been estimated that 350 million people--approximately 5% of the world population--have been infected by this virus. Of the people infected, in 90% to 95% of them there will be a spontaneous resolution of the disease. In 5% to 10% of the cases, though, the infection will persist and a chronic hepatitis will develop that may evolve leading, in the end, to liver cirrhosis, liver failure and/or carcinoma of the liver. The diagnosis of the different stages of the disease (i.e., acute, chronic infection) is performed using modern serologic techniques. Physicians, more recently, are having access to a series of laboratory tests which permit them to evaluate the viral load, replication of the virus and to testing of the efficacy of new anti-viral drugs. For the treatment of chronic hepatitis B new agents have been tested and some are being used with different degrees of success, such as, alfa-interferon, lamivudine, famciclovir, and adefovir dipivoxil, among others. Active immunization, using modern recombinant vaccines, are lately, the most important instrument of control of the infection caused by the hepatitis B virus.