HBsAg Seroclearance in Chinese Patients Receiving Lamivudine Therapy for Chronic Hepatitis B Virus Infection

Abstract

We report two Chinese patients in whom lamivudine treatment resulted in HBsAg seroclearance. One patient received lamivudine, and another patient received 12-week famciclovir treatment followed by lamivudine. Lamivudine was maintained after HBeAg seroconversion. These two patients lost HBsAg at 24 and 27 months (ages, 23 and 19.3 years, respectively) and developed measurable titer of anti-HBs after 65 and 71 months of therapy, respectively. The liver biochemistry was normal after HBeAg seroconversion. The serum hepatitis B virus (HBV) DNA levels were undetectable (<200 copies/ml) both at the time of HBeAg seroconversion and at the last follow-up. Liver biopsy of one patient showed nearly normal histology, with undetectable intrahepatic total HBV DNA and covalently closed circular DNA. In conclusion, lamivudine therapy can result in HBsAg seroclearance at an early age even though the phenomenon is rare.

CASE REPORTS

Case 1.

The first Chinese patient, a 21-year-old male, was randomized to receive 100 mg of lamivudine daily from the start of the trial (August 1997). He was found to be HBsAg positive during a routine checkup at age 16. He probably had chronic hepatitis B virus (HBV) infection since childhood, as his sister was also an HBV carrier. He had HBV genotype B (determined by the line probe assay INNO-LiPA HBV Genotyping; Innogenetics NV, Ghent, Belgium). The pretreatment liver biochemistry was as follows: albumin, 45 g/liter; bilirubin, 9 μmol/liter; alanine aminotransferase (ALT), 398 U/liter. The HBV DNA level measured by the Cobas Amplicor HBV Monitor test (Roche Diagnostics, Branchburg, N.J.; lower limit of detection of 200 copies/ml) was 7.7 × 10⁶ copies/ml. After reaching the peak ALT level of 554 U/liter at week 4 of lamivudine treatment, he had HBeAg seroconversion with undetectable HBV DNA level (<200 copies/ml) at month 3 of therapy (November 1997). He was maintained on lamivudine after HBeAg seroconversion. The HBV DNA level remained undetectable at month 6 of therapy. He had follow-up every 8 weeks under the trial protocol till week 48. From then on, he had regular follow-up every 3 to 6 months in the Hepatitis Clinic, Queen Mary Hospital, The University of Hong Kong, Hong Kong. The ALT levels were normal throughout the subsequent follow-up. HBsAg became negative at 24 months (at 23 years of age; July 1999). Anti-HBs first became positive, with a titer of 17 MU/ml, at 65 months (at 26.4 years of age; January 2003). The liver biochemistry at the last follow-up (71.5 months; July 2003) was as follows: albumin 45 g/liter; bilirubin, 8 μmol/liter; ALT, 37 U/liter. The serum HBV DNA remained undetectable. Liver biopsy showed minimal necroinflammation (grade 1 out of 18) and fibrosis (grade 1 out of 4) according to the Knodell scoring system (histologic activity index). Both the intrahepatic total HBV DNA and the covalently closed circular (ccc) DNA were undetectable, as measured by the Invader HBV DNA assay (Third Wave Technologies, Inc., Madison, Wis.; lower limits of detection for the relaxed circular and ccc forms of DNA were 10⁵ and 10⁴ copies/ml of DNA extract, respectively). With all these favorable results, the lamivudine was stopped at 71.5 months (August 2003). Six months after cessation of lamivudine (February 2004), the HBV DNA and HBsAg remained undetectable and the anti-HBs titer was 93 MU/ml.

Case 2.

The second Chinese patient was a 17-year-old male randomized to receive 500 mg of famciclovir three times a day in September 1997 for 12 weeks, followed by 100 mg of lamivudine daily. He was found to be HBsAg positive by screening his blood for donation at age 16. He had HBV genotype C. The pretreatment liver biochemistry was as follows: albumin, 50 g/liter; bilirubin, 8 μmol/liter; ALT, 59 U/liter. The HBV DNA level measured by the Cobas Amplicor HBV Monitor test was 6.7 × 10⁶ copies/ml. The HBV DNA level decreased to 2.1 × 10⁴ copies/ml at month 6 of therapy. He had follow-up every 8 weeks under the trial protocol till week 48. From then onwards, he had regular follow-up every 3 to 6 months in our Hepatitis Clinic, Queen Mary Hospital, The University of Hong Kong. He had fluctuating ALT levels, ranging from 29 to 132 U/liter before achieving HBeAg seroconversion at month 15 of therapy (December 1998). The HBV DNA level was undetectable at the time of HBeAg seroconversion. HBsAg became negative at 27 months (at 19.3 years of age; December 1999). Lamivudine was maintained after HBeAg seroconversion but was stopped after 30 months of therapy on the patient's own initiative (March 2000). Anti-HBs was detectable at the titer of 421.2 MU/liter at the last follow-up (71 months; at 22.9 years of age; August 2003). He had persistent normal ALT levels till the last follow-up. The latest liver biochemistry was as follows: albumin, 43 g/liter; bilirubin, 11 μmol/liter; ALT, 12 U/liter. The serum HBV DNA was undetectable. The option of liver biopsy was declined by the patient.

The ideal goal for the treatment of chronic HBV infection is total eradication of HBV.

To date, the best indicators for achieving this goal are HBV surface antigen (HBsAg) seroclearance, with or without the development of antibodies against HBsAg (anti-HBs), and the absence of detectable serum and intrahepatic HBV DNA, as indicated by sensitive assays. HBsAg seroclearance occurs spontaneously at around 1 to 1.7% per year in Caucasian patients and at 0.1 to 0.8% per year in Asian patients (1, 6, 9, 10). Following alpha interferon treatment, 65% of Caucasian patients who lose the HBV e antigen (HBeAg) also become HBsAg negative upon subsequent follow-up (3). However, this phenomenon occurs only in around 2.4% of the Asian population according to a long-term study of patients receiving alpha interferon (11).

Lamivudine has been widely used to treat chronic hepatitis B and is equally efficacious in Caucasian and Asian populations. There is an incremental increase in the HBeAg seroconversion rate with prolonged therapy (16 to 32% for the first year and 50% for the fifth year) (12). Dienstag and his colleagues have reported that 23% of Caucasian patients receiving lamivudine who have HBeAg seroconversion lose HBsAg after a median period of 36 months (2). However, HBsAg seroclearance in Chinese nontransplant patients receiving lamivudine has never been described. HBsAg seroclearance in Chinese patients receiving lamivudine has been reported only for patients with either bone marrow or liver transplantation (5, 7, 8). In these patients, the HBsAg seroclearance is most likely not related to lamivudine but due to adoptive immunity transfer from the donors (5, 7, 8). We report two Chinese patients in whom lamivudine treatment resulted in HBsAg seroclearance. Both patients were in a previously reported randomized trial comparing lamivudine and famciclovir (4).

Randomized trial.

One hundred patients with chronic hepatitis B were recruited into a comparative trial of lamivudine (n = 50) versus famciclovir (n = 50) (NUCB 4003) sponsored by GlaxoSmithKline Research Laboratories (4). The study was approved by the Ethics Committee, Institute Review Board, The University of Hong Kong, and Queen Mary Hospital, Hong Kong, and performed in the Department of Medicine, Queen Mary Hospital, The University of Hong Kong. The trial was started in August 1997. Patients were positive for HBsAg and HBeAg for at least 6 and 3 months, respectively, before entering the trial. Patients who were positive for anti-hepatitis C virus or anti-hepatitis D virus were excluded. Trial patients were randomized to receive either 100 mg of lamivudine daily or 500 mg of famciclovir three times a day for the first 12 weeks (the comparative phase). After the comparative phase, all patients were given lamivudine on an open-label basis. Patients were followed up at weeks 2, 4, 8, and 12 during the comparative phase and then at 8-week intervals till week 48. Sera were taken for liver biochemistry, HBeAg/anti-HBe, and HBsAg/anti-HBs during every follow-up. The result of this trial at the 24-week point has been reported previously (4).

Discussion.

The phenomenon of HBsAg seroclearance in nontransplant chronic hepatitis B patients has been reported only for the Caucasian population (2). We believe that the HBsAg seroclearance in these two Chinese patients was attributable to the use of lamivudine. According to our previous study of 92 patients with spontaneous HBsAg seroclearance, the mean age of patients with HBsAg seroclearance is 48 years (13). Our patients in the present study had HBsAg seroclearance occurring at a very early age (19.3 and 23 years). Both patients were maintained on lamivudine after HBeAg seroconversion. Whether the achievement of HBsAg seroclearance was related to the continued viral suppression is unknown.

Spontaneous HBsAg seroclearance at an early age is advantageous since patients with HBsAg seroclearance before 50 years of age have better liver histology and reduced risk of development of hepatocellular carcinoma (13). It would be interesting to study whether lamivudine-induced HBsAg seroclearance before 50 years of age is associated with a reduced risk of development of cirrhosis-related complications and hepatocellular carcinoma. The liver biopsy of the first patient showed nearly normal histology. In addition, the serum ALT, albumin, and bilirubin levels of both patients were persistently normal after HBsAg seroclearance till the time of last follow-up. Both patients also developed anti-HBs.

The serum HBV DNA levels of these two patients, measured by the highly sensitive PCR assay, became undetectable both at the time of HBeAg seroconversion and at the last follow-up. For patient 2, it is highly likely that the HBV has been eradicated since there has been no reappearance of HBsAg 41 months after cessation of lamivudine therapy. For patient 1, longer follow-up after cessation of lamivudine therapy is required to determine whether HBV has been totally eradicated, though both the total HBV DNA and the ccc DNA inside the hepatocytes were undetectable in the liver biopsy sample.

In conclusion, lamivudine therapy can result in HBsAg seroclearance at an early age even though the phenomenon is rare. At least in patient 2, the persistence of anti-HBs for 41 months after cessation of lamivudine therapy suggested that HBV had been totally eradicated.