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发表于 2004-8-10 04:28
Discussion
Lamivudine can overcome cytotoxic T-lymphocyte hyporesponsiveness,[5,6] and this may serve as a bridge to subsequent HBV-specific immune therapies, which may cause changes in the balance between viral replication and the host's immune response in favor of eradication of chronic HBV infection. In contrast, therapeutic vaccination may act better and more safely under conditions of low viremia. It was shown that therapeutic vaccination of chronically infected woodchucks under conditions of low viremia shifts the cytokine profile against viral antigens toward Th0/Th1.[7] In an open-labeled trial, it was also reported that inoculating those patients with vaccine containing HBsAg creates a situation where immune system cells secrete beneficial cytokines, augmenting the effects of lamivudine therapy.[8] For this purpose, we aimed to evaluate therapeutic immunostimulation in a chronic hepatitis B patient who received 18 monthly intramuscular vaccinations with HBsAg/pre-S2 in combination with daily lamivudine, and it was hoped that the immune cytotoxic restoration associated with lamivudine therapy would be synergistically added to the specific proliferative responses associated with vaccination.[9]
Usually, serum HBV DNA levels become undetectable within a few months of lamivudine therapy.[10] In the present case, HBV DNA levels were persistently detectable until the ninth month of therapy, and the patient did not normalize ALT activity during the entire period of therapy. In contrast to other studies, we failed to show any synergism between lamivudine therapy and vaccination.[7,8] In the European trial, two groups of chronic hepatitis B patients received combination HBV vaccine/lamivudine therapy or combination HBV vaccine/lamivudine/interleukin-2 therapy. After the therapy was stopped, seven of nine vaccine/lamivudine and two of five vaccine/lamivudine/interleukin-2 recipients had undetectable HBV DNA. Ultimately, four patients demonstrated viral clearance, although one experienced viral reactivation, with spontaneous clearance shortly thereafter.[8] In another uncontrolled trial, it was reported that simultaneous administration of interferon α and HBsAg vaccination in patients previously not responding to interferon alone appears to be a safe and well-tolerated procedure, and response rates are similar to or even higher than to interferon in naive patients.[11]
In the current case, there was a viral breakthrough at month 11, and sequence analysis of the reverse-transcriptase domain of the resistant viral strain revealed the selection of mutant virus (L180M). Thus, combination of lamivudine and anti-HBV vaccine therapy did not have any effect on preventing viral resistance, which is one of the main problems during lamivudine therapy that limits the efficacy of the drug. In addition, HBV vaccination administered after negativation of serum HBV DNA on treatment with lamivudine did not prevent viral multiplication relapse and did not induce HBeAg seroconversion. The clinical course of chronic hepatitis B in patients with lamivudine-resistant mutants is variable.[2] HBeAg seroconversion has been reported in approximately 25% of the patients who continued treatment after the detection of lamivudine-resistant mutants.[1] In the presented case, the additional 6-month course of combination therapy again did not have any beneficial effect on the prevention of the occurrence of breakthrough during therapy or on relapse after the emergence of the drug-resistant mutant. The patient did not experience any side effects-neither evidence for immune complex-mediated disease nor severe worsening of liver disease-during the period of vaccination or during the follow-up period, indicating the safety of therapeutic vaccinations.
Although it appears to be a safe and well-tolerated regimen, the data from the present case demonstrated that combination of anti-HBV vaccine and lamivudine did not eliminate viral DNA despite prolonged treatment and did not have any effect on preventing resistant-type HBV. However, due to the single-patient experience, no firm conclusions can be drawn concerning the combined effect of lamivudine administration and vaccination. Whether combination of reinforced specific vaccination and lamivudine might have an effect in limiting the occurrence of breakthrough during therapy and relapse after lamivudine discontinuation needs to be analyzed in further randomized trials.
Reprint Address
Reprint requests to Kendal Yalcin, MD, Division of Hepatology, Dicle University School of Medicine, 21280 Diyarbakir, Turkey. Email: [email protected]
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