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Gastroenterology MedPulse

[B]Re-Treatment of Patients With Anti-HBe-Positive Chronic Hepatitis B Who
Relapsed After an Initial Course of Lamivudine[/B]

Interferon and lamivudine are the only agents which have been approved for
the treatment of chronic hepatitis B.
Aliment Pharmacol Ther 18(9) 2003


Gene Expression in HCV-Associated Hepatocellular Carcinoma - Upregulation of
a Gene Encoding a Protein Related to the Ubiquitin-Conjugating Enzyme
Hepatocellular carcinoma (HCC) develops most frequently as a consequence of
chronic hepatitis B or C.
Liver Int 23(5) 2003

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Re-Treatment of Patients With Anti-HBe-Positive Chronic Hepatitis B Who Relapsed After an Initial Course of Lamivudine


G. A. Niro, T. Santantonio, R. Fontana, M. Insalata, D. Facciorusso, F. Signorile, F. Perri, A. Guastadisegni, D. Gioffreda, O. Palmieri, G. Pastore, A. Andriulli
Aliment Pharmacol Ther 18(9):933-940, 2003. © 2003 Blackwell Publishing
Posted 11/20/2003
Summary and Introduction
Summary
Aim: To evaluate the efficacy of a long-term course of lamivudine monotherapy in patients with anti-HBe-positive chronic hepatitis B who relapsed after the first course of either lamivudine/interferon (n = 16; Group 1) or lamivudine (n = 20; Group 2).
Methods: Biochemical and virological tests were performed every 3 months. At baseline and breakthrough, the region coding for the YMDD amino acid motif was sequenced.
Results: The length of re-treatment averaged 24 months. The virological response peaked at 6 months (94.4%), and declined to 66.7% and 50% at 12 and 24 months, respectively. The rates of breakthrough were 2.9%, 31.4% and 48.6% at 6, 12 and 24 months, respectively. By the second year, responders amounted to 62.5% and 40% in Groups 1 and 2, respectively (P = 0.10). The 18 responders at month 24 are still on therapy after 25-51 months of treatment: 14 still maintain a response, nine from Group 1 and five from Group 2.
Conclusions: Re-treatment with lamivudine can control viral replication. This effect is maintained for the initial 12 months in two-thirds of patients, but afterwards the duration of response lessens due to the development of viral resistance.
Introduction
Interferon and lamivudine are the only agents which have been approved for the treatment of chronic hepatitis B. In hepatitis B e antigen (HBeAg)-negative chronic hepatitis B, randomized clinical trials with interferon therapy have shown that the end-of-treatment response is in the range 38-90% in treated patients;[1-5] however, approximately one-half of responders relapsed when therapy was discontinued,[5] so that a sustained response was achieved in 15-25% of patients.[6]
Lamivudine has been shown to be of benefit in patients with HBeAg-negative chronic hepatitis B, providing a 1-year response rate of 70%; however, only 10% of patients maintained the response when the drug was withdrawn.[7-9] The safety of lamivudine has suggested that continuous therapy may be beneficial. The major shortcoming of prolonged therapy is the time-related increasing risk of the emergence of lamivudine-resistant hepatitis B virus (HBV) mutants.[10] Moreover, acute exacerbations of hepatitis may occur after the discontinuation of lamivudine.[11]
In a previous study, we demonstrated that a 12-month course of combination therapy with lamivudine plus interferon was able to prevent the emergence of YMDD mutants;[12] however, the combination regimen failed to prevent both relapse and hepatitis flares when treatment was withdrawn.[12] Rescue therapies for HBeAg-negative chronic hepatitis B patients with worsening liver disease caused by lamivudine-resistant mutants are being evaluated. Recent data have shown that adefovir dipivoxil, a promising anti-HBV agent that has been approved by the Food and Drug Administration, but is not yet licensed in Italy, effectively inhibits replication of YMDD mutants resistant to lamivudine and hence averts the resultant disease.[13] Furthermore, in HBeAg-positive patients, re-treatment with lamivudine was usually effective in controlling exacerbations.[11] Whether this therapeutic option might also be effective for patients with HBeAg-negative chronic hepatitis B remains to be established.
Herein, we have evaluated the benefits of long-term re-treatment with lamivudine monotherapy in HBeAg-negative chronic hepatitis B patients who relapsed after a previous course of either lamivudine monotherapy or combination therapy with lamivudine plus interferon.
Patients and Methods
Patients
This is a follow-up study of our previous controlled trial which evaluated the efficacy of a 12-month course of lamivudine, administered as either monotherapy (100 mg/day), or in combination with interferon (5 MU three times a week; cumulative dose, 780 MU), in Caucasian patients from the Apulia region in southern Italy. All patients were anti-HBe positive, negative for hepatitis C and D virus (HCV and HDV) and human immunodeficiency virus (HIV) infections and similar with respect to age, sex, alanine transaminase and HBV-DNA levels at baseline.[12] In the initial cohort of patients, therapy had to be discontinued per protocol after 1 year of treatment in all cases; of the 50 patients enrolled in the initial trial, five patients who developed a YMDD mutant during the first course of therapy were judged to be unsuitable for lamivudine re-treatment; they showed a virological breakthrough before month 12 and YMDD mutants were detected by sequence analysis. They were excluded because re-treatment in this setting is ineffective due to the prompt reappearance of viral resistance.
Nine more patients from the initial cohort were enrolled in experimental clinical trials using entecavir or adefovir dipivoxil and were also excluded from the present study. The remaining 36 agreed to be re-treated with lamivudine when the disease relapsed after therapy discontinuation; none had experienced a virological breakthrough or had developed YMDD mutants during the previous course of therapy.
Lamivudine Re-Treatment
After an initial evaluation, the 36 patients were administered lamivudine orally at a dose of 100 mg once daily. Patients were seen in the out-patient clinic and had blood drawn at baseline and routinely every 3 months throughout treatment. According to recent guidelines, lamivudine was continued thereafter as long as there was evidence of biochemical and virological response.[6] The initial protocol called for therapy to continue for 5 years. Normal alanine transaminase values and undetectable HBV-DNA (< 0.5 pg/mL) were used as criteria for response. Breakthrough was defined as the reappearance of serum HBV-DNA by molecular hybridization during treatment after an initial virological response, and biochemical breakthrough was defined as an increase in alanine transaminase activity. For patients with virological and biochemical breakthrough, re-treatment had to be stopped whenever alanine transaminase levels reached > 10 times normal, or persistently abnormal alanine transaminase values were found; lamivudine was continued for another 6-9 months in the case of a lower or sporadic increase in alanine transaminase levels.
All patients were treated as part of a two-centre, open-label, prospective trial of long-term therapy of hepatitis B. The protocol was approved by the ethics committees at the two centres, and all patients gave written informed consent.
Laboratory and Virological Testing
Routine laboratory tests, performed on each clinical visit, included serum alanine and aspartate transaminase, serum direct and total bilirubin, albumin and complete blood counts. HBV, HDV, HCV and HIV serological markers were detected by commercial enzyme immunoassays (Abbott Laboratories, North Chicago, IL, USA; Sorin Biomedica, Saluggia, Italy; Ortho Diagnostic Systems, Raritan, NJ, USA). Serum HBV-DNA was detected by a sandwich capture hybridization assay (Digene Diagnostics, Hybrid Capture II, Abbott Laboratories, North Chicago, IL, USA), which has a lower detection limit of 0.5 pg/mL (1.42 x 105 copies/mL). Virological resistance was evaluated by direct sequencing of the polymerase gene at baseline and during treatment in patients with breakthrough, as described previously.[12] With this method, the lower detection limit of a minor viral population is about 20% of the total population.[14] In addition, at baseline, the HBV polymerase region was amplified and analysed by means of the line probe assay (INNO LiPA HBV-DR, Innogenetics, Ghent, Belgium), which identifies 5% of a specific variant within a mixed viral population.[15]
Statistical Analysis
Data were analysed using the SPSS statistical package (version 6.1.3; SPSS Inc., Chicago, IL, USA). Continuous variables were checked for normality using the Shapiro-Wilks test. If normally distributed, Student's t-test was used to evaluate differences between mean values. Otherwise, the Mann-Whitney U-test was carried out to test differences between median values. Pearson's chi-squared test (or Fisher's exact test, when appropriate) was used for categorical variables. A P value of less than 0.05 was considered to be significant. Kaplan-Meier statistics were used to evaluate differences in the cumulative risk of breakthrough occurrence between the two groups of patients, sorted according to the previous course of treatment.
Results
Baseline Features
The 36 patients enrolled in the present study included 16 (44%) patients initially treated with lamivudine-interferon combination therapy (Group 1) and 20 patients previously treated with lamivudine monotherapy (Group 2) (Table 1). The majority of patients in both groups were males (86%), with an age range of 18-64 years (mean, 47 years). The average age and sex were similar in the two patient groups.
The time elapsed between the initial treatment and current re-treatment was 8.1 ± 7.2 months (range, 2-23 months), and was shorter in Group 1 (3.3 ± 1.8 months) than in Group 2 (12.7 ± 7.4 months). At the start of re-treatment, the median alanine transaminase level was 340 IU/L; 39%, 19% and 42% of patients had alanine transaminase levels below five times normal values, 5-10 times normal values and more than 10 times normal values, respectively. Alanine transaminase levels more than eight times the norm were more frequent in patients from Group 1 (P = 0.04). HBV-DNA was positive in all patients, with a mean value of 157 pg/mL; at baseline, 58.3% of patients had HBV-DNA levels of less than 100 pg/mL and 41.6% had HBV-DNA levels of more than 100 pg/mL. The numbers of patients with median HBV-DNA levels of < 100 pg/mL were significantly different in the two patient groups, and values of > 100 pg/mL were more frequently observed in Group 1 (P = 0.02).
At the time of initiation of lamivudine re-treatment, no drug-resistant HBV variant was identified by sequence analysis. Negative results were also obtained by the INNO LiPA HBV-DR assay in all but one patient, in whom a mixture of predominant wild-type and mutated virus strains was detected (wt + L528M/YVDD + L528M/YIDD).
Virological Changes During Therapy
At the time of this analysis, the total treatment duration ranged from 12 to 51 months, and averaged 24 months. The percentages of virological response at different time points during lamivudine re-treatment are provided in Figure 1: serum HBV-DNA levels decreased rapidly in all but one patient and were no longer detectable by hybridization assay within 3 months in 32 patients (88.9%). Of the four non-responders at 3 months, three were HBV-DNA negative at 6 months, whereas the remaining patient was still HBV-DNA positive at 6 months and was considered as a primary non-responder. The virological response peaked at 6 months of re-treatment with a value of 94.4%; thereafter, the percentages of responders began to decline and were 66.7% at 12 months, 55.6% at 18 months and 50.0% at 24 months. The decline in responders was counterbalanced by the number of patients with a virological breakthrough; of the 35 patients with an initial response to re-treatment (32 patients at 3 months and three patients at 6 months), the rates of breakthrough at 6, 12, 18 and 24 months were 2.9%, 31.4%, 42.9% and 48.6%, respectively.

Figure 1. Virological response during long-term re-treatment of 36 anti-HBe-positive patients with chronic hepatitis B who relapsed after an initial course of lamivudine with or without interferon.
The frequencies of virological response and breakthrough during long-term lamivudine re-treatment are reported separately for the 16 patients initially treated with lamivudine-interferon combination therapy (Group 1) and the 20 patients previously treated with lamivudine monotherapy (Group 2) (Figure 2). At 3 and 6 months of re-treatment, responders amounted to 94% and 100%, respectively, in Group 1 patients, and 85% and 90%, respectively, in Group 2 patients. After 1 year of treatment, 12 patients (75%) from Group 1 were still in full remission, whereas the proportion of responders from Group 2 had decreased to 60% (12 of 20); this difference was not statistically significant (P = 0.48). By the second year of re-treatment, the number of responders had declined further to 10 (62.5%) and eight (40%) in Group 1 and Group 2, respectively (P = 0.10). These 18 responders are still on therapy; at present, the re-treatment duration is in the range 25-51 months; 14 of the 18 patients have maintained a therapeutic response, nine in Group 1 and five in Group 2.

Figure 2. Percentage of response (R) and breakthrough (BR) during long-term re-treatment with lamivudine. Patients were divided according to the previous course of therapy: combination therapy with lamivudine and interferon (Group 1) and lamivudine monotherapy (Group 2).
At 6 months of re-treatment, all Group 1 patients were still responding, whereas a virological breakthrough was detected in one of the 19 initial responders (5.3%) in Group 2. At 12 and 24 months of re-treatment, a virological breakthrough had occurred in four (25%) and six (37.5%) patients from Group 1, and in seven (31.8%) and 11 (57.9%) patients from Group 2; these differences were not statistically significant (P = 0.49 and P = 0.31, respectively). By Kaplan-Meier analysis, at 42 months of continuous re-treatment with lamivudine monotherapy, the cumulative proportions of patients who were lamivudine resistant were 82% in Group 2 and 44% in Group 1 (log-rank test: P = 0.154) (Figure 3).

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Figure 3. Kaplan-Meier analysis of virological breakthrough in anti-HBe-positive patients with chronic hepatitis B re-treated with lamivudine monotherapy. Patients were divided according to the previous course of therapy: combination therapy with lamivudine and interferon (IFN + LAM; Group 1) and lamivudine monotherapy (LAM; Group 2).
The predictors of long-term response to re-treatment are evaluated in Table 2. Responders did not differ from those who experienced a breakthrough with regard to gender, alanine transaminase values, HBV-DNA levels, presence of cirrhosis and previous treatment with lamivudine-interferon or lamivudine monotherapy. However, they differed in age [responders being older than those who developed an HBV mutant (P = 0.04)] and in the time interval between initial treatment and re-treatment [responders being re-treated after a shorter period (P = 0.01)]. Two features of responders approached statistical significance: higher baseline alanine transaminase levels and previous treatment with lamivudine-interferon.
Biochemical Changes During Therapy
Serum alanine transaminase levels declined during lamivudine therapy, generally after the decrease in HBV-DNA levels. Alanine transaminase levels were normal in 68% of patients at 3 months, in 83% at 6 months, in 61% at 1 year and in 44% at 2 years. The rise in alanine transaminase levels during treatment followed the development of resistance. The alanine transaminase deviation pattern at the time of virological breakthrough differed: alanine transaminase reached values of acute hepatitis (10 times normal values) in nine patients, five of whom demonstrated an alanine transaminase peak which coincided with the reappearance of HBV-DNA and the detection of YMDD variants; in the remaining four patients, the peak occurred within 8 months from breakthrough. Apart from general malaise and asthenia, no patient became icteric or developed signs of liver decompensation. These nine patients were maintained on lamivudine for another 6 months; alanine transaminase levels were persistently elevated (five times normal) during treatment. In the remaining 12 breakthrough patients, milder elevations of alanine transaminase levels were observed.
Viral Resistance
The detection of YMDD mutants was demonstrated in all 21 patients at breakthrough. The YIDD mutant was detected in eight patients; YVDD mutants were found in nine patients in combination with L528M; YIDD mutants in combination with L528M were detected in four patients.
Characterization of Non-Responder
A 58-year-old man with histologically demonstrated liver cirrhosis agreed to re-treatment for biochemical and virological relapse which occurred 2 months after the first course of lamivudine monotherapy. At baseline before re-treatment, the patient had high serum alanine transaminase levels and was HBV-DNA positive by hybridization assay; a wild-type YMDD sequence was detected by direct sequencing. The virological and biochemical profile of this patient on re-treatment is reported in Figure 4. After 2 months of re-treatment, the YVDD/L528M mutant replaced the wild-type virus and, subsequently, the YIDD mutant replaced the YVDD mutant. Lamivudine was withdrawn at month 16 and interferon therapy was initiated on a compassionate basis. After a transient hepatitic flare, during which the re-emergence of L528M/YVDD as the dominant mutant viral population was observed, alanine transaminase normalized and HBV-DNA tested negative. The baseline serum sample was also analysed by the INNO LiPA HBV-DR test, and a mixture of wild-type virus, L528M/YVDD and L528M/YIDD mutants was found.

Figure 4. Biochemical, virological and molecular analysis of an anti-HBe-positive chronic hepatitis B patient treated with lamivudine and interferon (IFN). ALT, alanine transaminase; HBV-DNA, hepatitis B virus DNA; WT, wild type.
Discussion
In patients with HBeAg-negative/HBV-DNA-positive chronic hepatitis B (pre-core mutant), a 12-month course of lamivudine monotherapy provides promising on-therapy results, but poor efficacy off therapy due to virological and biochemical relapses.[7] For this reason, long-term therapy with lamivudine has been recommended in order to suppress viral replication and control liver disease.[6] The major shortcoming of this approach is the development of resistance, which limits efficacy in a high proportion of patients. In a previous controlled study, we demonstrated that the emergence of lamivudine-resistant mutations can be prevented by combining lamivudine with interferon: no patient receiving combination therapy developed YMDD mutants as long as therapy was administered, whereas 19% of patients treated with lamivudine alone experienced a virological breakthrough due to YMDD mutants during the 12-month course of monotherapy. However, this beneficial effect was lost after discontinuation of therapy, when marked increases in HBV-DNA and serum alanine transaminase levels were observed in all patients.[12] Although it remains to be ascertained whether prolonging combination therapy for more than 12 months could maintain the response and avoid the appearance of mutants, dual therapy with lamivudine and interferon rather than lamivudine monotherapy alone may be suggested as a first-line therapeutic option for anti-HBe-positive patients with chronic hepatitis B.
At present, therapeutic options for anti-HBe-positive patients with chronic hepatitis B who develop resistance to lamivudine, and for those who relapse after the discontinuation of lamivudine, are being evaluated. Adefovir has been proven to be effective in both instances;[13] however, at the time of initiation of the present study, this drug was available only in the liver transplant setting and interferon had been temporarily withdrawn from prescription by Italian health authorities. Therefore, we were forced to rely on lamivudine. In the present study, we evaluated the efficacy of a second lamivudine course in anti-HBe-positive patients who had failed a previous course.
Our study demonstrated that the 6- and 12-month virological responses were 94.4% and 66.7%, respectively, which are comparable with the 81.7% and 65% response rates reported in the largest published trial by Tassopoulos et al.[7] For the first time, these results establish the benefit of re-treatment with lamivudine monotherapy for anti-HBe-positive patients.
A crucial issue is how long re-treatment with lamivudine monotherapy should be maintained in this setting. In the industry-sponsored multi-national ongoing study of extended lamivudine therapy in anti-HBe-positive patients naive to this drug, the response declined from 67% at 6 months, to 51%, 34% and 29% after 12, 24 and 36 months, respectively.[16] In four additional clinical studies, approximately 30% of patients maintained a full virological and biochemical response after 3 years of therapy.[17-20] The observed 60% response rate at 24 months of therapy found in our study, together with the actuarial 39% response rate at 42 months, are similar to the results obtained in published series and establish the benefit of long-term re-treatment with lamivudine monotherapy in anti-HBe-positive patients who have failed a previous course of treatment with the drug. In our trial, responders are still on lamivudine therapy and are scheduled to undergo repeat liver biopsy after 5 years of continuous therapy in order to evaluate the benefits of continuing lamivudine therapy. Moreover, long-term re-treatment was associated with the development of resistance and a loss of response in 21 of the 36 enrolled patients after 6-38 months of lamivudine monotherapy.
Interestingly, the first appearance of mutants in patients from Group 1 was delayed by 6 months compared with that in patients from Group 2. In addition, at 12 and 24 months of re-treatment, the rates of breakthrough were 25% and 37.5%, respectively, in Group 1, and 36.8% and 57.9%, respectively, in Group 2; by Kaplan-Meier analysis, breakthroughs at month 42 of re-treatment were 42% in Group 1 and 82% in Group 2. These differences, although not significant, probably due to the small sample size, underline the beneficial effect of combination therapy in preventing or delaying the emergence of drug-resistant mutants.
Only one patient in this study did not respond; in this patient, the presence of subpopulations of YMDD mutants at low levels in the serum sample obtained before treatment was shown by INNO LiPA HBV-DR assay, but not by direct sequencing. This observation confirms the clinical importance of methods which are more sensitive than direct DNA sequencing for the detection of mixed viral populations and are especially useful for predicting the response to therapy in patients already exposed to lamivudine.
In conclusion, in patients with anti-HBe-positive chronic hepatitis B with a relapse after lamivudine therapy, re-treatment is capable of controlling viral replication. This effect is maintained for the initial 12 months of therapy, after which a high rate of viral resistance limits the long-term efficacy of this therapeutic strategy.

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Tables
Table 1. Demographic and Baseline Features of 36 Patients with Hepatitis B e Antigen (HBeAg)-negative Chronic Hepatitis B Divided According to a Previous Course of Either Lamivudine Plus Interferon (Group 1) or Lamivudine Monotherapy (Group 2)


Group 1Group 2P
No. of patients1620
Age (years) (mean ± s.d.)47.4 ± 7.544.2 ± 11.80.32
Gender, males (n, %)14 (87)17 (85)0.82
Cirrhosis at histology (n, %)4 (25)5 (25)1
Time elapsed between two treatments (months) (mean ± s.d.)3.3 ± 1.812.7 ± 7.40.0001
ALT (IU/L), median value (Q3-Q1)*459 (201-768)192 (114-466)0.01
ALT < 8 x normal (n, %)5 (31)13 (65)0.04
HBV-DNA (pg/mL), median value (Q3-Q1)*82 (12-179)307.5 (80-684)0.06
HBV-DNA < 100 pg/mL (n, %)10 (63)5 (25)0.02

ALT, alanine transaminase; HBV-DNA, hepatitis B virus DNA.
* Q3-Q1 indicates the difference between the 75th and 25th percentile values.


Table 2. Occurrence of Breakthrough in Anti-HBe-positive Patients with Chronic Hepatitis B During Lamivudine Re-Treatment in Relation to their Baseline Characteristics


Responders (R)Breakthroughs (BR)P (BR vs. R)
No. of patients1421
Age (years) (mean ± s.d.)49.1 ± 6.842.7 ± 11.10.044
Gender (male/female)12/218/31
Previous IFN/LAM (n, %)9 (64)7 (33)0.07
Cirrhosis (n, %)4 (29)4 (19)0.68
Time elapsed between two treatments (months) (mean ± s.d.)4.9 ± 5.610.8 ± 7.50.01
ALT (IU/L), median value (Q3-Q1)*379 (172-799)221 (117-481)0.07
ALT < 8 x normal (n, %)5 (36)13 (62)0.13
HBV-DNA (pg/mL), median value (Q3-Q1)*92 (11-653)174 (54-554)0.53
HBV-DNA < 100 pg/mL (n, %)8 (57)7 (33)0.16

ALT, alanine transaminase; HBV-DNA, hepatitis B virus DNA; IFN, interferon; LAM, lamivudine.
* Q3-Q1 indicates the difference between the 75th and 25th percentile values.


References
Hadziyannis S, Bramou T, Makris A, Moussoulis G, Zignego L, Papaioannou C. Interferon alpha-2b treatment of HBeAg negative/serum HBV-DNA positive chronic active hepatitis type B. J Hepatol 1990; 11: S133-6.
Fattovich G, Farci P, Rugge M, et al. A randomized controlled trial of lymphoblastoid interferon-alpha in patients with chronic hepatitis B lacking HBeAg. Hepatology 1992; 15: 584-9.
Pastore G, Santantonio T, Milella M, et al. Anti-HBe-positive chronic hepatitis B with HBV-DNA in the serum: response to a 6-month course of lymphoblastoid interferon. J Hepatol 1992; 14: 221-5.
Lampertico P, Del Ninno E, Manzin A, et al. A randomized controlled trial of a 24-month course of interferon alfa 2b in patients with chronic hepatitis B who had hepatitis B virus DNA without hepatitis B e antigen in serum. Hepatology 1997; 26: 1621-5.
Manesis EK, Hadziyannis SJ. Interferon a treatment and retreatment of hepatitis B e antigen-negative chronic hepatitis B. Gastroenterology 2001; 121: 101-9.
Lok AS, Heathcote EJ, Hoofnagle JH. Management of Hepatitis B 2000 - Summary of a Workshop. Gastroenterology 2001; 120: 1828-53.
Tassopoulos NC, Volpes R, Pastore G, et al. Lamivudine Precore Mutant Study Group. Efficacy of lamivudine in patients with hepatitis B e antigen-negative hepatitis B virus DNA-positive (precore mutant) chronic hepatitis B. Hepatology 1999; 29: 889-96.
Santantonio T, Mazzola M, Iacovazzi T, Miglietta A, Guastadisegni A, Pastore G. Long-term follow-up of patients with anti-HBe/HBV DNA-positive chronic hepatitis B treated for 12 months with lamivudine. J Hepatol 2000; 32: 300-6.
Rizzetto M, Volpes R, Smedile A. Response of pre-core mutant chronic hepatitis B infection to lamivudine. J Med Virol 2000; 61: 398-400.
Liaw YF, Leung NWY, Chang TT, et al. Effects of extended lamivudine therapy in Asian patients with chronic hepatitis B. Gastroenterology 2000; 119: 172-80.
Honkoop P, de Man RA, Niesters HGM, Zondervan PE, Schalm SV. Acute exacerbation of chronic hepatitis B virus infection after withdrawal of lamivudine therapy. Hepatology 2000; 32: 635-9.
Santantonio T, Niro GA, Sinisi E, et al. Lamivudine/interferon combination therapy in anti-HBe positive chronic hepatitis B patients: a controlled pilot study. J Hepatol 2002; 36: 799-804.
Perrillo R, Schiff E, Yoshida E, et al. Adefovir dipivoxil for the treatment of lamivudine-resistant hepatitis B mutants. Hepatology 2000; 32: 129-34.
Schuurman R. State of the art of genotypic HIV-1 drug resistance. Curr Opin Infect Dis 1997; 10: 480-4.
Stuyver L, Van Geyt C, De Gendt S, et al. Line probe assay for monitoring drug resistance in hepatitis B virus-infected patients during antiviral therapy. J Clin Microbiol 2000; 38: 702-7.
Esteban R. Clinical and histologic outcome of extended lamivudine in patients with HBeAg negative chronic hepatitis. Hepatology 2001; 34: 1097A.
Hadziyannis SJ, Papatheodoridis GV, Dimou E, Laras A, Papaioannou C. Efficacy of long-term lamivudine monotherapy in patients with hepatitis B e antigen-negative chronic hepatitis B. Hepatology 2000; 32: 847-51.
Lok AS, Hussain M, Cursano C, et al. Evolution of hepatitis B virus polymerase gene mutations in hepatitis B e antigen-negative patients receiving lamivudine therapy. Hepatology 2000; 32: 1145-53.
Paganin S, Barbon V, Ciancio A, et al. Long-term lamivudine monotherapy in chronic e-antigen negative hepatitis B: efficacy and breakthrough. J Hepatol 2001; 34(Suppl. 1): 134.
Buti M, Cotrina M, Jardi R, et al. Two years of lamivudine therapy in anti-HBe-positive patients with chronic hepatitis B. J Viral Hepat 2001; 8: 270-5.
Reprint Address

Correspondence to: Dr G. A. Niro, Division of Gastroenterology, Casa Sollievo della Sofferenza Hospital, Viale Cappuccini, 71013 San Giovanni Rotondo (FG), Italy. E-mail: [email protected]



G. A. Niro*, T. Santantonio?, R. Fontana*, M. Insalata?, D. Facciorusso*, F. Signorile?, F. Perri*, A. Guastadisegni?, D. Gioffreda*, O. Palmieri*, G. Pastore? & A. Andriulli*

*Division of Gastroenterology, Hospital 'Casa Sollievo della Sofferenza' IRCSS, San Giovanni Rotondo, Italy; ?Department of Internal Medicine, Immunology and Infectious Diseases, University of Bari, Bari, Italy