Antiviral therapy: Hepatitis B

Transcription

1 British Medical Bulletin (1990) Vol. 46, No. 2, pp The British Council 1990 Antiviral therapy: Hepatitis B M R Jacyna H C Thomas Department of Medicine and Hepatology, St Marys Hospital Medical School, Imperial College, University of London, London Antiviral therapy for chronic hepatitis B virus infection can result in clearance of replicating virus from the liver and prevention of progression to cirrhosis in a substantial proportion of patients. Adenosine arabinoside monophosphate, a potent inhibitor of HBV replication, is of limited usefulness because it causes significant neuromuscular toxicity. Acyclovir alone is relatively nontoxic, but is clinically ineffective in eliminating HBV from the liver. Lymphoblastoid or recombinant alpha-interferons are the best option at present and offer up to a 50% chance of long-term inhibition of HBV replication (with only minor side-effects) in patients who acquire the infection in adulthood. However alpha-interferon therapy alone is not effective when infection is acquired from birth. In this latter group of patients, prednisolone pre-treatment followed by alpha-interferon is currently under evaluation. Most adults infected with the hepatitis B virus (HBV) will develop a clinical or subclinical self-limiting acute hepatitis, with spontaneous clearance of hepatocytes supporting HBV replication within a few weeks of infection. No specific antiviral therapy is required for this group of patients. Rarely, a very small number of individuals will develop a more severe fulminant hepatitis, the treatment of which is described elsewhere in this issue. Some patients (5-10%) become chronically infected with HBV, and this group run the major risk of developing cirrhosis and liver cell cancer. At present, antiviral therapy is indicated for patients with chronic HBV infection who have active viral replication within the liver usually, but not invariably, 'e' antigen positive and who /90/ /$ 10.00

2 ANTIVIRAL THERAPY 369 also have biochemical and/or histological evidence of liver cell injury. The relationship between active HBV replication and liver cell damage has been well described 1 " 3 and the goal of antiviral therapy is permanent elimination of hepatocytes supporting HBV replication. Several studies have now shown that disappearance of HBeAg from the serum and the development of anti-hbe (either spontaneously 1 "" 3 or after antiviral therapy 4 ) results in a biochemical and histological remission in the majority of infected individuals. However 5% of anti-hbe positive patients will still continue to have disease activity, 5 albeit sometimes severe. 6 As there is a natural rate of spontaneous seroconversion from HBeAg to anti-hbe, varying from 5-16% per annum, 5 ' 7 studies evaluating anti-viral therapies should include a matched but untreated control group. Unfortunately many antiviral studies have not been performed in this way, making interpretation of results difficult. HBe ANTIGEN POSITIVE CHRONIC HBV INFECTION These patients are potentially infectious and have chronic hepatitis of variable severity. Single agent studies Adenine arabinoside and adenine arabinoside monophosphate The purine analogue, adenine arabinoside (ARA-A) is a potent inhibitor of DNA polymerase activity. The clinical usefulness of ARA-A is limited by its poor aqueous solubility, which results in it having to be given by intravenous (i.v.) infusion. A controlled study of i.v. ARA-A has shown that a 10 day course produced HBe to anti-hbe seroconversion rates of 40%. 8 Most clinical trials on ARA-A have focussed on its highly water-soluble derivative, adenine arabinoside monophosphate (ARA-AMP) which can be given by intramuscular injection. Six recent controlled studies of ARA-AMP are summarized in Table 1. 9 ~ 14 As can be seen, there are wide variations in response rates, as low as 5% in some studies 12 and as high as 80% in others. 15 The most likely reason for this variation is heterogeneity in the populations being studied: the highest seroconversion rates are seen in heterosexuals and the lowest in male homosexuals. 16 The major problem with ARA- AMP is its toxicity and many patients develop painful sensory

3 370 VIRAL HEPATITIS Table 1 Controlled trials of treatment of chronic hepatitis B infection with ARA- AMP Regimen 10 mg/kg/day 4-8 weeks 10 mg/kg/day for 5 days, 5 mg/kg/day for the remaining 23 days 1 cycle as above 1 cycle as above 2 cycles as above 1 cycle as above 3 cycle Patients Untreated 10% (1/10) 20% (2/10) 9 55% (10/18) 26% (5/9) 10 40% (4/10) 20% (2/10) 11 5% (1/18) 5% (1/17) 12 40% (6/15) 0% (0/14) 13 9% (2/22) 14% (4/27) 14 References peripheral neuropathies and severe myalgias. Some of these sideeffects may cause long-standing disability, as a result of which ARA-AMP has recently been withdrawn for use as a single agent in chronic hepatitis B infection. Ways of reducing the toxicity of ARA-AMP are to limit the duration of treatment to less than 28 days, 17 and also to conjugate ARA-AMP with lactosaminated albumin, a neoglycoprotein which specifically penetrates hepatocytes. This allows a much lower dose (a third to a sixth) of ARA- AMP to be used, with a resultant reduction in toxicity. An uncontrolled pilot study of this compound given i.v. to 5 subjects with chronic hepatitis B infection, resulted in seroconversion in 3 of the patients and with no side effects observed. 18 There seems to be no doubt that ARA-A and its derivatives inhibit hepatitis B viral replication and may be successful in some patients in producing a seroconversion response, but the poor results in some patient groups (particularly male homosexuals) and the toxicity of ARA-A and ARA-AMP restrict their usefulness. Further studies of short courses of ARA-AMP (to rapidly reduce HBV replication) preceding other types of therapy (including immune modulation), and more work on the lactosaminated albuminated ARA-AMP derivative are needed.

4 ANTIVIRAL THERAPY 371 Acyclovir Acyclovir, which is used to treat herpes infections, has also been used in chronic hepatitis B infection. Given intravenously over 7 days, it causes a reduction in DNA-polymerase 19 and HBV-DNA levels. 19 ' 20 Very few controlled studies in patients. with chronic hepatitis B infection have been performed (Table 2;ref 21). Acyclovir, if given rapidly intravenously, is nephrotoxic, 20 and attempts to give it orally are limited by its poor absorption from the gut. The pro-drug of acyclovir, 6-deoxy-acyclovir, is essentially completely absorbed when taken orally. Only one pilot study has been performed with this agent with disappointing results and no seroconversions. 22 As a single agent, acyclovir and its derivatives are not a valid option. Type I Interferons (alpha and beta) The mechanism of action of interferons in chronic hepatitis B infection is unknown, but several changes in the immune system and in the infected hepatocyte are believed to be important. An increase in MHC Class I protein display 23 and viral protein expression 24 in the hepatocyte occur within 24 hours of starting therapy. An increase in the helper/suppressor T lymphocyte cell ratio occurs at 6-8 weeks in those subjects who successfully undergo HBe to anti-hbe seroconversion. Changes in humoral immunity also occur. Patients who respond to therapy either have IgM anti-hbc present before treatment or develop it during the course of therapy. 25 Changes in cell-mediated immunity may also occur but have not yet been documented. Alpha-interferon, mainly derived from monocytes and transformed B lymphocytes, was initially obtained from buffy-coat leucocytes, but most recent studies have used lymphoblastoid Table 2 Controlled acyclovir trials of treatment of chronic hepatitis B infection with Regimen Patients Treated Untreated References 45 mg/kg/day Intravenously for 28 days 30 26% (4/15) 6% (1/15) 21

5 372 VIRAL HEPATITIS (obtained from a stimulated lymphoblastoid cell line) or recombinant alpha-interferons. Beta-interferon, obtained from fibroblasts, is produced by recombinant DNA technology. Leucocyte alpha interferon: A randomized controlled study of human leucocyte alpha-interferon in chronic hepatitis B infection 26 showed that low doses for 6 weeks produced no short or long term response (Table 3). Lymphoblastoid alpha interferon: Several controlled studies of human lymphoblastoid alpha-interferon in chronic hepatitis B infection have been published 27 " 30 and are summarized in Table 4. Seroconversion rates vary widely. The largest of these Table 3 Controlled trial of treatment of chronic hepatitis B infection with leucocyte interferon Regimen Patients Treated Untreated References < 12 x 10 6 MU daily for 6 weeks 20 20% (2/10) 40% (4/10) 26 Table 4 Controlled trials of treatment of chronic hepatitis B infection with lymphoblastoid interferon Regimen Patients Treated Untreated References 10 U( x 10 6 )/m 2 thrice weekly for 6 months U( x 10 6 )/m 2 daily for 28 days U( x 10 6 )/m 2 daily for 1 month then thrice weekly for 5 months U(xl0 6 )/m 2 thrice weekly for 3 months 61 26% (6/23) 0% (0/23) 27 14% (2/14) 0% (0/16) 28 88% (8/9) 22% (2/9) 29 32% (12/37) 4% (1/24) 30

6 ANTIVIRAL THERAPY 373 studies, a multicentre study from Italy, has shown very promising early results, with a very high seroconversion rate of 88% in the first 18 patients recruited. 29 However, the latest data on 66 patients enrolled to this study has shown a more modest overall serocon version rate of 50 %. 31 Another study comparing 3 months of lymphoblastoid interferon with ARA-AMP therapy similarly indicated a 45% seroconversion rate for the interferon-treated patients. 32 Further studies reveal that 6 months of therapy is no better (and tolerated worse) than only 3 months therapy, 33 and also that thrice weekly injections for 3 months are more effective and better tolerated than daily injections for one month. A review of the factors that appear to predict a seroconversion response indicate that Chinese chronic carriers (presumably infected from birth) show a very poor response, whereas European heterosexual carriers (who usually acquire their infection in adulthood) respond the best. 24 Other factors that are predictive of a seroconversion response are high serum transaminases, 30 marked hepatic inflammatory activity, 30 the presence of serum IgM anti-hbc 25 and low serum HBV-DNA. 34 Recombinant alpha interferon: Results from several controlled trials 34 " 39 indicate that recombinant alpha-interferon used alone will induce complete remissions in certain HBsAg carriers (Table 5). Once again, homosexual males seem less responsive than heterosexuals, in particular those who are anti-hiv antibody positive. 34 Poor results have been obtained in Chinese adults 37 and children. 40 Many of these carriers have been infected from birth and it is possible that this alters their capacity to respond to interferon, although immunogenetic factors have not been excluded. Development of interferon antibodies whilst on recombinant alpha-interferon occurs in about 25% of patients 41 and may reduce the chances of successful seroconversion, particularly if they appear whilst the patient is still HBV-DNA positive. Beta interferon An uncontrolled study from Japan using 3-6 U( x 10 6 )/m 2 given daily by intravenous infusion suggested a seroconversion rate of about 35%. 42 One preliminary small controlled study from Germany however indicated that, as a single agent, beta-interferon did not contribute significantly to clinical improvement in chronic HBV infection. 43

7 374 VIRAL HEPATITIS Table 5 Controlled trials of treatment of chronic hepatitis B infection with recombinant human alpha interferon Regimen Patients Treated Untreated References U( x 10 6 )/m 2 thrice weekly for 3-6 months U( x 10 6 )/m 2 every other day for 4 months U( x 10 6 )/m 2 thrice weekly for 3 months U( x 10 6 )/m 2 thrice weekly for 3-6 months U( x 10 6 )/m 2 thrice weekly for 3-6 months 24 U( x 10 6 )/m 2 /day or 10 U(xlO 6 )/m 2 thrice weekly for 4 months 45 Type II Interferon (gamma) 19% (6/32) 0% (0/9) 34 32% (10/31) 14% (2/14) 35 19% (7/37) 0% (0/23) 36 16% (7/45) 0% (0/15) 37 33% (6/18) 17% (1/6) 38 32% (10/31) 7% (1/14) 39 No controlled studies of gamma interferon in chronic hepatitis B infection have yet been published. Uncontrolled studies have shown immunomodulatory effects and slight reductions in HBV DNA-polymerase activity but no seroconversions after 8 weeks therapy with MU daily. 44 As a single agent, gamma interferon is unlikely to be of much clinical value, but combination studies with type I interferons may be more promising. Interleukin-2 Again, no controlled studies using this agent in chronic hepatitis B have been published. An uncontrolled pilot study has shown that DNA-polymerase levels fell in some treated individuals and HBe antigen to antibody seroconversion was observed in 3 out of 10 treated patients at one year. 45 Without a control group these data are encouraging but difficult to interpret.

8 ANTIVIRAL THERAPY 375 Combination therapies Although it is believed that the liver damage in chronic hepatitis B infection is immunologically mediated, 46 immunosuppressive therapy in the form of corticosteriod therapy alone has largely been abandoned. The immune system cannot be safely suppressed to a degree that prevents liver damage and several studies have now shown that, particularly in patients with more advanced liver disease, serious hepatic decompensation may occur when the steroids are withdrawn. 47 ' 48 However, a short course of steroids can provide a 'rebound' immunostimulatory effect when the steroids are stopped which, in combination with other antiviral and immunomodulatory therapies, may provide a useful approach, particularly in chronic carriers who have acquired their infection at birth. Prednisolone and interferon A small uncontrolled study on 5 patients pre-treated with steroids followed by interferon, resulted in 3 of the patients seroconverting. 49 The results of the only controlled study so far 50 suggest slightly better seroconversion rates than after interferon alone (Table 6). It should however be noted that in this study the interferon was given daily, whereas most other studies interferon is administered thrice weekly. An interesting aspect of this study is that 3 anti-hiv antibody positive patients were treated and 2 seroconverted. Both of these patients had normal CD4 to CD8 ratios, and this indicates that anti-hiv positivity per se should not be used as a predictor of treatment failure. Patients with serious Table 6 Controlled trials of treatment of chronic hepatitis B infection with prednisolone pre-treatment followed by interferon Regimen Patients Treated Untreated References 6 weeks of mg of prednisolone, followed by 3 months interferon 5 U( x 10 6 )/m 2 /day 39 44% (8/18) 19% (4/21) 50

9 376 VIRAL HEPATITIS hepatic disease, however, must be excluded from this type of therapy. Encouraging preliminary results have also been obtained in a study from Taiwan, where the combination of prednisolone pre-treatment followed by lymphoblastoid interferon is being compared to placebo and interferon alone. 51 Long-term results of this study are awaited with interest. Prednisolone and adenine arabinoside Two controlled studies of prednisolone pre-treatment followed by ARA-A 9 or ARA-AMP 12 have been performed (Table 7). The seroconversion rates are encouraging, but once again the toxicity of ARA-A and ARA-AMP is the limiting factor. Acyclovir and interferon A pilot uncontrolled study has shown that this combination may be better than either agent alone. 52 One small controlled study on acyclovir plus interferon in chronic hepatitis B infection has been performed. 53 In this study, 40% of 18 patients treated with lymphoblastoid interferon and oral deoxy-acyclovir for 4 months seroconverted from e to anti-e, compared to 0% of 18 patients in the control group. Interferon alone may seroconvert up to 60% and, as no comparison with an identical treatment period of Table 7 Controlled trials of treatment of chronic hepatitis B infection with prednisolone pre-treatment followed by ARA-A or ARA-AMP Regimen Patients Treated Untreated References Prednisolone 40 mg/day for 4 weeks then ARA-A 10 mg/kg 4-8 weeks 19 55% (6/9) 20% (2/10) 9 Prednisolone 40 mg/day for 8 weeks then ARA-A 10 mg/kg for 5 days then 5 mg/kg for 23 days 28 73% (8/11) 0% (1/17) 12

10 ANTIVIRAL THERAPY 377 interferon alone was performed, interpretation is difficult. A further case-report from The Netherlands has also suggested that the combination of acyclovir and interferon may also be useful in HBV-associated glomerulonephritis. 54 Interferon and adenine arabinoside One study of a 6 month combination of ARA-AMP (given twice daily every other month) and leukocyte interferon (given twice daily, alternating every other month with ARA-AMP) in 13 patients, showed no benefit of the combination over placebo alone. 14 Many of the patients in this study suffered considerable neuromuscular toxicity, but the cumulative dose of ARA-AMP used in this study was large, and the interferon was administered twice daily, rather than thrice weekly. Tailored regimes that utilize a shorter course of lactosaminated albuminated ARA-AMP pretreatment (to reduce HBV-DNA levels) followed by thrice weekly interferon, may be more succesful and less toxic. Type I and Type II Interferons Two small studies on the combination of alpha and gamma interferons have been performed. 55 ' 56 Although a therapeutic effect was seen in one of these studies, 55 the other study did not suggest any benefit from the combination, and gamma interferon alone had minimal inhibitory activity on viral replication, did not show any additive or synergistic effects when added to alphainterferon, and contributed greatly to side-effects. 56 In a pilot controlled study of beta and gamma interferons in combination (Table 8), 50% of the treated patients succesfully lost HBV infection. 57 No comparison with either of the interferons alone was undertaken and further studies are needed to evaluate these preliminary results. ANTI-HBe POSITIVE CHRONIC HBV INFECTION The majority of anti-hbe positive patients with chronic HBs antigenaemia have no evidence of inflammatory liver disease (serum transaminases and liver histology are normal). A minority of patients however are HBe antigen negative, have seroconverted to anti-hbe, yet remain viraemic and frequently have a more severe and rapidly progressive liver disease. 58 ' 59 This disease is

11 378 VIRAL HEPATITIS Table 8 Controlled trials of treatment of chronic hepatitis B infection with combination beta and gamma interferon Regimen Patients Treated Untreated References 3 MU Beta-IFN daily and 1 MU gamma-1fn for 23 days 20 50% (5/10) 10% (1/10) 57 cause by a mutant virus that has a novel translational stop codon in the pre-core/core gene of HBV. 60 Hepatocytes infected with this mutant virus cannot secrete HBe antigen. The anti-hbe positive patients with continuing viraemia due to replication of the mutant HBV have been treated with recombinant interferon without success. 61 This remains an outstanding problem. Conclusions As single antiviral agent therapy for chronic HBV infection, lymphoblastoid or recombinant alpha-interferons appear to be the best choice, and offer up to a 50% change of HBe antigen seroconversion (elimination of replicating virus) in those patients who acquired their infection after the neonatal period. Higher seroconversion rates may be obtained with combination therapies, in particular those utilizing a pre-treatment period with prednisolone, but it will be important to compare these regimes with treatment by alpha-interferon alone. One major advantage of the combined prednisolone-interferon approach is that patients acquiring the infection at birth, who do not respond to alphainterferon alone, may respond in up to 50% of cases. These patients constitute by far the largest proportion of chronic carriers (mostly Chinese and South-East Asian carriers). Further studies of newer single agents and also of different combination regimes are required. REFERENCES 1 Realdi G, Alberti A, Rugge M, et al. Seroconversion from hepatitis Be antigen to anti-hbe in chronic hepatitis B virus infection. Gastroenterology 1980; 79:

12 ANTIVIRAL THERAPY Liaw YF, Chu CM, Su IJ, Huang MJ, Lin DY, Chang-Chien CS. Clinical and histological events preceding hepatitis B e antigen seroconversion in chronic type B hepatitis. Gastroenterology 1983; 84: Hoofnagle JH, Dusheiko GM, Seef LB et al. Seroconversion from hepatitis B e antigen to antibody in chronic type B hepatitis. Ann Intern Med 1981; 94: Brook MG, Petrovic L, McDonald JA, Scheuer PJ, Thomas HC. Histological improvement after anti-viral treatment for chronic hepatitis B infection. J Hepatol 1989; 8: Fattovitch G, Rugge M, Brollo L et al. Clinical, virologic and histologic outcome following seroconversion from HBeAg to anti-hbe in chronic hepatitis type B. Hepatology 1986; 6: Wu JC, Lee S-D, Tsay S-H, et al. Symptomatic anti-hbe positive chronic hepatitis B in Taiwan with special reference to persistant HBV replication and HDV superinfection. J Med Virol 1988; 25: Viola LA, Barrison IG, Coleman JC, et al. Natural history of liver disease in chronic hepatitis B surface antigen carriers; A survey of 100 patients from Great Britain. Lancet 1981; ii: Bassendine MF, Chadwick RG, Salmeron J, et al. Adenine arabinoside therapy in HBsAg-positive chronic liver disease; a controlled study. Gastroenterology 1981; 80: Yokosuka O, Omata M, Imazeki F, et al. Combination of short term prednisolone and adenine arabinoside in the treatment of chronic hepatitis B. Gastroenterology 1985; 89: Trepo C, Hantz O, Ouzan D, et al. Therapeutic efficacy of ARA-AMP in symptomatic, HBeAg positive CAH:a randomized placebo controlled study. Hepatology 1984; 4: Hoofnagle JH, Hanson RG, Minuk GY, et al. Randomized controlled trial of adenine arabinoside monophosphate for chronic type B hepatitis. Gastroenterology 1984; 86: Perillo R, Regenstein F, Bodicky C, et al. Comparative efficacy of adenine arabinoside 5'-monophosphate and prednisolone withdrawel followed by adenine arabinoside 5'-monophosphate in the treatment of chronic active hepatitis type B. Gastroenterology 1985; 88: Weller IVD, Lok ASF, Sherlock S, et al. Randomised controlled trial of adenine arabinoside 5'-monophosphate in chronic hepatitis virus infection. Gut 1985; 26: Garcia G, Smith CI, Weissberg JI, et al. Adenine arabinoside monophosphate (vidarabine) in combination with human leukocyte interferon in the treatment of chronic hepatitis B. Ann Intern Med 1987; 107: Trepo C, Ouzan D, Fontagnes T, et al. Therapeutic activity of vidaribine in symptomatic chronic active hepatitis related to HBV. J Hepatol 1986; 3 (Suppl 2): S97-S Novick DM, Lok ASF, Thomas, et al. Diminished responsiveness of homosexual men to antiviral therapy for HBsAg positive chronic liver disease. J Hepatol 1984; 1: Lok ASF, Wilson LA, Thomas HC. Neurotoxicity associated with adenosine arabinoside monophosphate in the treatment of chronic hepatitis B virus infection. J Antimicrob Chemother 1984; 14: Fiume L, Cerenzia MRT, Bonino F, et al. Inhibition of hepatitis B virus replication by vidaribine monophosphate conjugated with lactosaminated serum albumin. Lancet 1987; ii: Smith CI, Scullard GH, Gregory PB, Robinson WS, Merigan TC. Preliminary studies of acyclovir in chronic hepatitis B. Am J Med 1981; 73: Weller IVD, Carreno V, Fowler MJF, et al. Acyclovir in hepatitis B antigenpositive chronic liver disease; inhibitiion of viral replication and transient renal

13 380 VIRAL HEPATITIS impairment with IV bolus administration. J Antimicrob Chemother 1983; 11: Alexander GJM, Fagan EA, Hegarty JE, Yeo J, Eddleston ALWF, Williams R. Controlled clinical trial of acyclovir in chronic hepatitis B virus infection. J Med Virol 1987; 21: Weller IVD, Tedder RS, Karayiannis P, Thomas HC, Fiddian AP. A pilot study of BW A515U (6-deoxyacyclovir) in chronic hepatitis B infection. J Hepatol 1986; 3 (Suppl 2): S119-S Pignatelli M, Waters J, Lever AML, et al. HLA class I antigens in hepatocyte membrane: Increased expression during interferon therapy of chronic hepatitis B infection. Hepatology 1986; 6: Thomas HC, Scully LJ. Antiviral therapy in chronic hepatitis B virus infection. Brit Med Bull 1986; 41: Chen G, Karayiannis P, McGarvey MJ, et al. Subclasses of anti-hbe in chronic HBV carriers: Changes during treatment with interferon and predictors of response. Gut 1989 (In Press) 26 Schalm SW, Heijtink RA. Spontaneous disappearance of viral replication and liver cell inflammation in HBsAg-positive chronic active hepatitis; results of a placebo vs. interferon trial. Hepatology 1982; 2: Alexander GJM, Brahm J, Fagan EA, et al. Loss of HBsAg with interferon therapy in chronic HBV infection. Lancet 1987; ii: Anderson MG, Harrison TJ, Alexander GJM, Zuckerman AJ, Murray-lyon IM. Randomised controlled trial of lymphoblastoid interferon for chronic active hepatitis B. J Hepatol 1986; 3 (Suppl 2): S225-S Barbara L, Mazzella G, Baraldini M, et al. A randomized controlled trial with human lymphoblastoid interferon vs no therapy in chronic hepatitis B infection. J Hepatol 1986; 3 (Suppl 2): S235-S Brook MG, Chan G, Yap I, et al. Randomised controlled trial of treatment with lymphoblastoid alpha-interferon in Caucasian males with chronic hepatitis B virus infection. Brit Med J 1989; 299: Mazzella G, Saracco G, Rizetto M, et al. Human Lymphoblastoid Interferon for the treatment of chronic hepatitis B. Am J Med 1988; 85 (Suppl 2A): Lok ASF, Novick DM, Karayiannis P, et al. A randomised study of the effect of adenine arabinoside 5'-monophospate (short or long course) and lymphoblastoid interferon on hepatitis B replication. Hepatology 1985; 5: Scully LJ, Shein R, Karayiannis P, McDonald JA, Thomas HC. Lymphoblastoid interferon therapy of chronic hepatitis B infection; a comparison of 12 vs. 24 weks of thrice weekly treatment. Hepatology 1987; 5: McDonald JA, Caruso L, Karayiannis P, et al. Diminished reponsiveness of male homosexual chronic hepatitis B carriers with HTLV-III antibodies to recombinant alpha-interferon. Hepatology 1987; 7: Hoofhagle JH, Peters M, Mullen KD, et al. Randomised controlled trial of a four month course of recombinant alpha interferon in patients with chronic type B hepatitis. Hepatology 1985; 5: Dusheiko GM, Kassianides C, Song E, et al. Loss of hepatitis B surface antigen in three controlled trials of recombinant alpha-interferon for treatment of chronic hepatitis B. In: Zuckerman AJ, ed. Viral hepatitis and liver disease. New York: Alan R Liss, 1988; pp Lok ASF, Lai CL, Wu PC, Leung EKY. A randomized controlled trial of recombinant alpha-2 interferon in Chinese patients with chronic hepatitis B virus infection, In: Zuckerman AJ, ed. Viral hepatitis and liver disease. New York: Alan R Liss, 1988; pp Perez V, Tanno H, Fay O, Barclay CA. Treatment of chronic active hepatitis B with recombinant interferon alpha A. In: Zuckerman AJ, ed. Viral hepatitis and liver disease. New York: Alan R Liss, 1988; pp

14 ANTIVIRAL THERAPY Hoofnagle JH, Peters M, Mullen KD, et al. Randomized, controlled trial of recombinant human alpha-interferon in patients with chronic hepatitis-b. Gastroenterology 1988; 95: Lai CL, Lok ASF, Lin HJ, et al. Placebo-controlled trial of recombinant alpha interferon in Chinese HBsAg carrier children. Lancet 1987; ii: Porres JC, Carreno V, Ruiz M, Marron JA, Bartolome J. Interferon antibodies in patients with chronic HBV infection treated with recombinant interferon. J Hepatol 1989; 8: Suzuki H, Ichida F, Fujisawa K, et al. Long term follow-up of HBe antigen positive chronic hepatitis treated with human interferon beta. Hepatology 1986; 6: Muller R, Deinhardt F, Hofschneider PH, Schmidt FW, Siegert W, Vido I. Long-term treatment with human fibroblast interferon in chronic hepatitis B infection. In: Szmunesss W, Alter HJ, Maynard JE, eds. Viral hepatitis. Philadelphia; The Franklin Institute Press, 1982; Lisker-Melman M, Peters M, Ambrus JL, et al. Effect of recombinant human gamma interferon therapy on immune function in patients with chronic type B hepatitis. In: Zuckerman AJ, ed. Viral hepatitis and liver disease. New York: Alan R Liss, 1988; pp Kakumu S, Fuji A, Yoshioka K, et al. Pilot study of recombinant human interleukin 2 for chronic type B hepatitis. Hepatology 1988; 8: Dienstag JL, Bhan AK, Klingenstein RJ, Savarese AM. Immunopathogenesis of liver disease associated with hepatitis B. In: Szmuness W, Alter HJ, Maynard JE, eds. Viral hepatitis. Philadelphia. Franklin Institute Press 1982; pp Nair PV, Tong MJ, Stevenson D, Roskamp D, Boone C. Effects of short-term high dose prednisone treatment of patients with HBsAg-positive chronic active hepatitis. Liver 1985; 5: Hoofnagle JH, Davis GL, Pappas C, et al. A short course of prednisolone in chronic type B hepatitis: report of a randomised, double blind, placebo controlled trial. Ann Intern Med 1986; 104: Omata M, Imazeki F, Yokosuka O, et al. Recombinant leukocyte A interferon treatment in patients with chronic hepatitis B virus infection. Pharmacokinetics, tolerance and biologic effects. Gastroenterology 1985; 88: Perillo R, Regenstein FG, Peters M, et al. Prednisone withdrawal followed by recombinant alpha interferon in the treatment of chronic hepatitis B. Ann Intern Med 1988; 109: Liaw YF, Lin SM, Sheen IS, Chen TJ, Chu CM. Treatment of chronic type B hepatitis in South-East Asia. Am J Med 1988; 85 (Suppl 2A): Schalm SW, Heijtink RA, Van Buuren HR, De Man RA. Acyclovir enhances the antiviral effect of interferon in chronic hepatitis B. Lancet 1986; ii: De Man RA, Schalm SW, Heijtink RA, et al. Long-term follow-up of antiviral combination therapy in chronic hepatitis B. Am J Med 1988; 85 (Suppl 2A): De Man RA, Schalm SW, Van Der Heijden, Ten Kate FWJ, Wolff ED, Heijtink RA. Improvement of hepatitis B associated glomerulonephritis after antiviral combination therapy. J Hepatol 1989; 8: Carreno V, Mora I. Combination of recombinant interferons alpha and gamma in treatment of chronic hepatitis B. Lancet 1987; ii: Di Bisceglie AM, Rustgi VK, Kassianides C, et al. Therapy of chronic hepatitis B with recombinant human alpha and gamma interferons. Hepatology (in press) 57 Caselmann WH, Eisenburg J, Hofschneider PH, Koshy R. Beta and Gamma interferons in chronic active hepatitis B. A pilot trial of short-term combination therapy. Gastroenterology 1989; 96: Chu CM, Karayiannis P, Fowler MJF, Monjardino J, Liaw YF, Thomas HC. Natural history of chronic hepatitis B virus infection in Taiwan: Studies of hepatitis B virus DNA in serum. Hepatology 1985; 5:

15 382 VIRAL HEPATITIS 59 Bonino F, Rosina F, Rizetto M, et al. Chronic hepatitis in HBsAg carriers with serum HBV-DNA and anti-hbe. Gastroenterology 1986; 90: Carman WF, Jacyna MR, Hadziyannis S, et al. Mutation preventing formation of heoatitis B e antigen in patients with chronic hepatitis B infection. Lancet 1989; ii: Brunetto MR, Oliveri F, Rocca G, et al. Natural course and response to interferon of chronic hepatitis B accompanied by antibody to hepatitis Be antigen. Hepatology 1989; 10: