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The significance of interferon and ribavirin combination therapy followed by interferon monotherapy for patients with chronic hepatitis C in Japan
Hepatology Research 29 (2004) 142–147
The significance of interferon and ribavirin combination therapy followed by interferon monotherapy for patients with chronic hepatitis C in Japan Naoki Hiramatsu a , Akinori Kasahara b , Fumihiko Nakanishi c , Takashi Toyama c , Masahiko Tsujii c , Shingo Tsuji c , Tatsuya Kanto a , Tetsuo Takehara a , Michio Kato d , Harumasa Yoshihara e , Masafumi Naito f , Kazuhiro Katayama f , Taizo Hijioka g , Hideki Hagiwara h , Shinji Kubota i , Masahide Oshita j , Haruya Meren j , Manabu Masuzawa j , Yoshimichi Haruna k , Eiji Mita l , Kunio Suzuki l , Norio Hayashi a,∗ a
Department of Molecular Therapeutics, Osaka University Graduate School of Medicine, 2-2, Yamadaoka, Suita City, Osaka 565-0871, Japan b Department of General Medicine, Osaka University Graduate School of Medicine, Osaka, Japan c Department of Internal Medicine and Therapeutics, Osaka University Graduate School of Medicine, Osaka, Japan d Osaka National Hospital, Osaka, Japan e Osaka Rousai Hospital, Osaka, Japan f Osaka Kouseinenkin Hospital, Osaka, Japan g National Osaka South Hospital, Osaka, Japan h Higashiosaka City Central Hospital, Osaka, Japan i Kansai Rousai Hospital, Hyoga, Japan j Osaka Police Hospital, Osaka, Japan k Osaka Prefectural Hospital, Osaka, Japan l Saiseikai senri Hospital, Osaka, Japan Received 26 December 2003; received in revised form 16 March 2004; accepted 25 March 2004
Abstract One hundred seventy-one patients with chronic hepatitis C were included in this study (genotype1 and high viral loads (1H), n = 130; non-1H, n = 37; N.D., n = 4). The combination therapy of interferon and ribavirin for 24 weeks with an additional 24 weeks of interferon monotherapy (48-week treatment) was undergone by 42 1H patients and 5 non-1H patients. The combination therapy of interferon and ribavirin was administered for 24 weeks in 67 1H patients and 22 non-1H patients. Among the 1H patients, the HCV relapse rate was significantly higher in those receiving 24-week combination treatment than in those receiving 48-week treatment (78% versus 42%, P = 0.003). Among the non-1H patients, no significant difference was found between them. Sustained virological response (SVR) rates were observed to decrease as the timing of HCV RNA disappearance was delayed. In spite of the small rate (16%), SVR was obtained from the patients who became negative for HCV RNA by week 24 (beyond week 12) only in those receiving 48-week treatment. In 1H patients, 24-week combination treatment followed by interferon monotherapy for 24 weeks was concluded to be the treatment offering the most hope among those that the medical insurance can be applied in Japan. © 2004 Published by Elsevier B.V. Keywords: Chronic hepatitis C; Interferon and ribavirin combination therapy; Combination therapy followed by IFN monotherapy
1. Introduction Interferon is the only available treatment for patients with chronic hepatitis C since HCV was discovered in ∗ Corresponding author. Tel.: +81-6-6879-3441; fax: +81-6-6879-3449. E-mail address: [email protected] (N. Hayashi).
1386-6346/$ – see front matter © 2004 Published by Elsevier B.V. doi:10.1016/j.hepres.2004.03.008
1989 [1–4]. Thirty percent of patients with chronic hepatitis C achieved SVR by interferon therapy but the efficacy was not satisfactory. Furthermore, in the patients considered to be the most treatment-resistant, that is, the 1H patients, only 5–8% showed SVR. In Japan, 40–50% of the patients with chronic hepatitis C belong to the 1H group. Therefore, finding how to eradicate the HCV RNA
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of 1H patients is most important for the treatment of chronic hepatitis C. Recently, ribavirin, a nucleic acid analogue, exhibiting in vitro activity against various kinds of DNA and RNA viruses has been developed. The combination therapy of ribavirin and interferon has been shown to be very useful in the eradication of HCV in patients with chronic hepatitis C [5–7], although the mechanism of action of ribavirin remains speculative and ribavirin monotherapy led to no significant decrease of the amount of HCV RNA in the patients with chronic hepatitis C [8]. Most recent studies, performed with large numbers of na¨ıve patients, have shown that the combination therapy of interferon and ribavirin can increase the SVR rate two-fold compared with interferon monotherapy for patients with chronic hepatitis C [9–12]. Especially, in the 1H patients, the combination therapy of interferon and ribavirin was more useful than in the other patients. Furthermore, Poynard et al. [10] showed that 1H patients treated by combination therapy for 48 weeks had a higher SVR rate than those treated for 24 weeks (28% versus 8%). Therefore, the combination therapy of interferon and ribavirin for 48 weeks is recommended as the standard therapy for 1H patients in Europe and the United States [13,14]. In Japan, the combination therapy of interferon and ribavirin was approved in 2001. However, the duration of the combination therapy is limited to 24 weeks in the medical insurance. As mentioned above, the SVR rate in 1H patients treated by the combination therapy for 24 weeks was clearly lower than those treated for 48 weeks. Furthermore, prolonged interferon monotherapy was reported to suppress relapse after cessation of therapy and to achieve a higher SVR rate in patients with chronic hepatitis C [15]. This study assessed the efficacy of the combination therapy of interferon and ribavirin for 24 weeks with an additional 24 weeks of interferon monotherapy compared with that of the combination therapy for 24 weeks.
2. Patients and methods 2.1. Patients The current study was conducted at Osaka University Hospital and the institutions of the Osaka Liver Disease Study Group. The 171 patients included in this study had HCV RNA detectable in serum by the polymerase chain reaction (PCR) method, had elevated ALT (above the upper limit of the normal) and had been histologically proven to have chronic hepatitis. No patients were positive for hepatitis B surface antigen and anti-human immunodeficiency virus antibody or had other forms of liver disease (such as alcoholic liver disease and autoimmune liver disease). This study protocol was carried out according to the ethical guidelines of the 1975 Declaration of Helsinki and informed consent was obtained from each patient.
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2.2. Determination of HCV RNA levels and HCV genotype Serum HCV RNA levels were quantified using branched DNA (bDNA) probe assay (version 2; Chiron, Dai-ichi Kagaku, Tokyo) [16,17] or combined PCR assay (AmplicorHCV monitor assay) [18]. In this study, a high viral load, as described previously [16,18,19], was designated as the condition of a serum HCV RNA level of more than 106 equivalents/ml by bDNA assay or more than 105 copies/ml serum by Amplicor-HCV monitor assay. HCV genome typing was classified by serological genotyping assay [20]. 2.3. Treatment schedule Of the 171 patients with chronic hepatitis C enrolled in this study, 130 had HCV RNA with genotype 1 and high viral loads (1H group), which were difficult to eradicate by anti-viral therapy. Of the remaining 41 patients, 37 had HCV RNA with genotype 2 or low viral loads (non-1H group); genotype or viral levels could not be determined for four. One hundred thirty-six patients in whom treatment had been done without the discontinuation of interferon till the end of the scheduled duration were studied (1H, n = 109; non-1H, n = 27). The combination therapy of interferon-␣-2b and ribavirin was administered for 24 weeks in 67 patients of the 1H group and 22 patients of the non-1H group. In this protocol, interferon-␣-2b was given intramuscularly every day for the first 2 weeks and then three times a week for the following 22 weeks in combination with ribavirin at a daily dose of 600 or 800 mg, depending on body weight (<60 or ≥60 kg, respectively). The combination therapy of interferon-␣-2b and ribavirin for 24 weeks, followed by interferon-␣-2b monotherapy three times a week for a further 24 weeks, was administered to 42 patients of the 1H group and 5 patients of the non-1H group. The pretreatment characteristics of the patients were similar (Table 1). The starting doses of interferon-␣-2b were 10 MU per day for 38, 6 MU per day for 127, and 3 MU per day for 6 patients. With ribavirin, 800 mg per day was started in 92, 600 mg per day in 77, and 400 mg per day in 2 patients. Among the 171 patients, the interferon dose was decreased in six patients during the treatment, and the interferon was stopped along with ribavirin in 33 patients (19%) due to side effects. The ribavirin dose was decreased in 43 patients (25%) during the treatment, and stopped without discontinuance of interferon in six patients. Eighty-seven patients (51%) completed treatment without discontinuance or dosage decrease of both drugs. After the sufficient informed consent at the end of the combination therapy of interferon and ribavirin, the patients themselves decided whether to be treated for 24 or 48 weeks. The information included the results of clinical trials of the combination therapy for 24 and 48 weeks in other countries, such as the SVR rate, HCV relapse rate.
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Table 1 Baseline characteristics of patients according to therapeutic protocol 24-week treatment
Age (yo) M/F ALT (IU/L) Fibrosis
1H group
Non-1H group
48-week treatment 1H group
67 55.8 ± 10.9 40/27 107 ± 71 1.9 ± 0.9
22 55.7 ± 12.8 15/7 102 ± 45 1.9 ± 1.2
42 54.0 ± 11.7 28/14 103 ± 58 1.8 ± 1.1
History of IFN treatment Na¨ıve 34 Relapser 21 Non-responder 11 Unknown 1
11 7 4 0
17 17 8 0
Note: All comparisons are not significant. Twenty-four-week treatment, interferon plus ribavirin treatment for 24 weeks; 48-week treatment, interferon plus ribavirin treatment for 24 weeks followed by interferon monotherapy for 24 weeks. 1H group, patients with genotype 1 and high viral load; non-1H group, patients other than 1H group. Fibrosis, Knodell’s histological score (category 4).
Also, side effects were presented and the combination therapy of interferon-␣-2b and ribavirin for 48 weeks was explained as not being covered by medical insurance in Japan. In the 47 patients who agreed to receive the additional 24 weeks of interferon monotherapy, the starting doses of interferon-␣-2b were 10 MU per day for 10, 6 MU per day for 35, and 3 MU per day for 2 patients. All patients completed the additional treatment although interferon was decreased only in one patient from 10 to 6 MU per day. 2.4. Statistical analysis Age, histological scores before interferon therapy, and serum ALT levels are expressed as mean ± S.D. The chi-squared test was used for statistical analysis of the comparison between group frequencies. When appropriate, the clinical and laboratory features of the two groups were compared by Student’s t-test. Histological evaluation was
substituted as a variable for Knodell’s histological scores [21]. 3. Results 3.1. Results of interferon and ribavirin combination therapy Seventy-five percent of all of the patients of 1H group (82/109), including not only patients who received 24-week treatment but also those who received 48-week treatment, had no detectable HCV RNA at 24 weeks after the beginning of combination therapy of interferon and ribavirin. This was also the case for 100% of the non-1H patients (27/27). In patients given 24-week treatment of combined interferon and ribavirin, 45 out of 67 of the 1H group were negative for HCV RNA at the end of therapy, but only 22% of the patients (10/45) showed no detectable HCV RNA at 24 weeks after cessation of therapy. On the other hand, HCV RNA was negative in all non-1H patients at the end of the 24-week treatment, and the SVR rate was 86% (19/22) (Fig. 1). In patients with 48-week treatment (24-week combination treatment, followed by 24-week interferon monotherapy), HCV RNA reappeared during interferon monotherapy (break through) in 11 out of 37 patients (30%) who were negative for HCV RNA at the end of 24-week combination therapy: SVR was finally reached in 15 out of 26 patients who continued to be sero-negative for HCV RNA at the end of 48-week treatment. On the other hand, HCV RNA was not cleared even by 48-week treatment in all five patients who were positive for HCV RNA at the end of 24-week treatment (Fig. 2). In the non-1H patients who received 48-week treatment, HCV RNA was negative in all five patients at the end of the 24-week treatment, and SVR was attained by 80% (4/5). The HCV RNA relapse rate after treatment was compared according to the duration of treatment. In all patients, 57% of those receiving 24-week treatment (38/67) had HCV RNA relapse, as compared with 39% of those receiving 48-week treatment (12/31). Among the 1H patients, a significant dif-
24wks (EOT) HCV (-) n=45
1H
HCV (-) n=10
n=67 HCV (+) n=35
SVR = 0% 0/22
HCV (+) n=22
Non-1H
Relapse rate = 78% 35/45
n=22
HCV (-) n=22
HCV (-) n=19
SVR = 86% 19/22
HCV (+) n=3
Fig. 1. Efficacy of the combination therapy (24-week treatment). 1H group, patients with genotype 1 and high viral load; non-1H group, patients other than those of the 1H group. EOT, end of treatment. HCV, serum HCV RNA positivity by polymerase chain reaction.
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48wks (EOT)
24wks
RNA (-) n=37
1H
n=42
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RNA (-) n=15
RNA (-) n=26
RNA (+) n=11
RNA (+) n=11
Relapse rate = 42% 11/26
SVR = 0% 0/11
BT = 30% 11/37 SVR = 0% 0/5
RNA (+) n=5
Fig. 2. Efficacy of the combination therapy followed by interferon monotherapy (48-week treatment). 1H group, patients with genotype 1 and high viral load; non-1H group, patients other than those of the 1H group. EOT, end of treatment. HCV, serum HCV RNA positivity by polymerase chain reaction. BT, break through.
The relationship between the timing of HCV RNA disappearance and SVR rate according to the duration of treatment was evaluated. As shown in Fig. 3A, in all patients receiving 24-week treatment, 71% (12/17) of the patients who had no detectable HCV RNA by week 4, 61% (11/18) by week 8 (beyond week 4), and 21% (4/19) by week 12 (beyond week 8) had SVR. Although 11 patients became negative for HCV RNA by week 24 (beyond week 12), none of them attained SVR. A tendency for a decrease in the SVR rate was observed as the timing of the HCV RNA disappearance was delayed. In the patients receiving 48-week treatment, 86% (6/7) of those who had no detectable HCV RNA by week 4, 100% (6/6) by week 8 (beyond week 4), 40% (4/10) by week 12 (beyond week 8), and 16% (3/19) by week 24 (beyond week 12) attained SVR. Among the 1H patients, the same tendency was also observed (Fig. 3B). In the patients receiving 24-week treatment, 50% (3/6) of those who had no detectable HCV RNA by week 4, 40% (4/10) by week 8 (beyond week 4), and 18% (3/17) by week 12 (beyond week 8) attained SVR. None of the 10 patients who became negative for HCV RNA by week 24 (beyond week 12) showed SVR. In the patients receiving 48-week treatment, 80% (4/5) of those who had no detectable HCV RNA by week 4, 100% (5/5) by week 8 (beyond week 4), 38% (3/8) by week 12 (beyond week 8), and 16% (3/19) by week 24 (beyond week 12) had SVR. In spite of the small rate (16%), SVR was obtained from the patients
1 00
100 80 SVR rate (%)
3.2. Timing of HCV RNA disappearance and efficacy of treatment
who became negative for HCV RNA by week 24 (beyond week 12) only in those receiving 48-week treatment. Fig. 4 shows the relationship between the timing of HCV RNA disappearance and the prediction value in 1H patients who received the combination therapy of interferon and ribavirin for 24 weeks. As the timing of the HCV RNA disappearance was late, the positive prediction value decreases and the negative prediction value increases. In particular, the negative prediction value at week 12 was 100%, that is, none
86 71 61
60 40 40 21
16
20 0 0 week 4
(A)
week 8 week 12 week 24 Timing of HCV RNA disappearance 1 00
100 80 80 SVR rate (%)
ference was found in HCV relapse rate between those receiving 24-week treatment and those receiving 48-week treatment (78% versus 42%, P = 0.003). Among the non-1H patients, HCV RNA relapsed in 14% (3/22) of those receiving 24-week treatment (Fig. 1) and 20% (1/5) of those receiving 48-week treatment.
60
50 40
38
40 20
18
16 0
0
(B)
week 4 week 8 week 12 week 24 Timing of HCV RNA disappearance
Fig. 3. Timing of HCV RNA disappearance and SVR rate (A) all patients, (B) patients with genotype 1 and high viral loads. (ⵦ) Combination therapy of interferon and ribavirin (24-week treatment); ( ) combination therapy followed by interferon monotherapy (48-week treatment).
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Predictive value (%)
100 80 60 40 20 0 4W
8W
12W
24W
Timing of HCV RNA disappearance Fig. 4. Timing of HCV RNA disappearance and prediction value in patients with genotype 1 and high viral loads who received the combination therapy of interferon and ribavirin for 24 weeks. (ⵦ) Positive prediction value; ( ) negative prediction value; ( ) predictive accuracy.
of the patients who were positive for HCV RNA at week 12 attained SVR.
4. Discussion In Japan, randomized control studies were performed on the combination therapy of interferon and ribavirin for 24 weeks in patients with chronic hepatitis C, and the combination therapy was approved in November 2001. However, the duration of the combination therapy is limited to 24 weeks in the medical insurance because of the lack of clinical mega-trial evidence for the combination therapy for 48 weeks in Japan. From the results of international trials, the SVR rate in 1H patients treated by the combination therapy for 48 weeks has been shown to be higher than that of those treated for 24 weeks [10]. Moreover, for interferon monotherapy, prolonged interferon treatment was reported to suppress relapse after cessation of therapy and to lead to a higher SVR rate in patients with chronic hepatitis C [15]. Our strategy, the interferon and ribavirin combination therapy with an additional 24 weeks of interferon monotherapy, was conducted against this background. Poynard et al. [22,23] evaluated the HCV RNA relapse rates after cessation of the combination therapy in na¨ıve patients with chronic hepatitis C. Among patients with genotype 1, the relapse rates were 62% in those treated by interferon and ribavirin combination therapy for 24 weeks and 26% in those treated for 48 weeks: among patients with genotype 2/3, 21% in those for 24 weeks and 15% in those for 48 weeks. Among patients with genotype 1, the SVR rate increased due to suppression of the relapse rate by the combination therapy for 48 weeks. On the other hand, the patients with genotype 2/3 require only 24 weeks of therapy. In our study, patients with genotype 1 and high viral load (1H group) were evaluated, distinguishing them from others (non-1H group) since the efficacy of anti-viral therapy for the 1H patients has been known to be remarkably low. Among the 1H patients, the HCV relapse rate
was significantly higher in those receiving 24-week combination treatment than in those receiving 48-week treatment, 24-week combination treatment followed by interferon monotherapy for 24 weeks (78% versus 42%, P = 0.003). Among the non-1H patients, no significant difference was found between those receiving 24-week treatment and those receiving 48-week treatment (14% versus 20%). These results indicate that our strategy of 48-week treatment is useful for the 1H group; the non-1H group seems to require only 24 weeks of therapy, similar to the patients with genotype 2/3 in the above-mentioned. In the 1H patients receiving 48-week treatment, HCV RNA reappeared during interferon monotherapy in 11 out of 37 patients (30%) who were negative for HCV RNA at the end of 24-week combination therapy. The break through phenomenon should be taken into account when the efficacy of this treatment is evaluated. The SVR ratio in 1H patients receiving 48-week treatment can be calculated from the prevalence of undetectable HCV RNA at 24 weeks after the beginning of combination therapy of interferon and ribavirin (75%, 82/109), of break though (30%, 11/37) and of HCV relapse rate (42%, 11/26); the expected SVR is 30% ((82/109) × (1 − (11/37)) × (1 − (11/26)) 0.30). In the same manner, the SVR ratio in 1H patients receiving 24-week treatment is expected to be 17% (82/109) × (1 − (35/45)) 0.17. In 1H patients, 48-week treatment, 24-week combination treatment followed by interferon monotherapy for 24 weeks, may be the useful treatment which can be actually performed in Japan. The relationship between the timing of HCV RNA disappearance and the SVR rate according to the duration of treatment was evaluated. SVR rates decreased with a delay in the timing of HCV RNA disappearance in patients receiving 24-week treatment; the negative prediction value at week 12 was 100%, that is, none of the patients who were positive for HCV RNA at week 12 had SVR. In spite of the small rate (16%), SVR was attained for patients who became negative for HCV RNA by week 24 (beyond week 12) only in those receiving 48-week treatment. Accordingly, treatment withdrawal should be offered to patients who remain HCV RNA-positive after 12 weeks of therapy if the patient cannot continue treatment for 48 weeks for reasons including side effects and social issues. The patients who were positive for HCV RNA at week 24 should stop treatment because additional interferon monotherapy for 24 weeks could not clear HCV RNA in all five patients who were positive for HCV RNA at week 24. Pol et al. [24] have reported the synergistic effect of ribavirin and interferon in 343 patients with the genotype 1b. In the study, ribavirin was administered for 4, 6, 12 months in combination with interferon-␣ for 12 months. A 12-month course of ribavirin achieved significantly greater virological efficacy than 6 or 4 months at the end of the 12-month course of interferon-␣ (59, 49, and 29%), the same trend seen at the end of follow-up duration (43, 36, and 21%). These results indicate that the maximum efficacy can be obtained
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when ribavirin is administered for 12 months in combination with interferon. In our study, the break through ratio was expected to decrease with the administration of ribavirin for 48 weeks. In fact, a patient to whom ribavirin was given again after the break through, achieved marked decrease of HCV RNA (data not shown). Thus, in some patients who were negative for HCV RNA during the combination treatment, the additional ribavirin can be essential for eradicating HCV RNA. Longer duration of combination therapy with interferon and ribavirin is also most effective for suppressing HCV RNA relapse after 24 weeks of therapy [22,23]. Therefore, we would like to emphasize that combination therapy of ribavirin and interferon for 48 weeks should be permitted even in Japan. At present, 24-week combination therapy followed by 24-week interferon monotherapy is thought to be the most useful therapy that the medical insurance can be applied in Japan for suppressing the relapse rate of HCV RNA, leading to SVR. Acknowledgements In addition to the study authors, the following institutions and physicians were participants in the Osaka Liver Disease Study Group (Digestive Disease Study Group of Osaka Renaissance): Osaka National Hospital, R. Sakamori; Osaka Rousai Hospital, N. Kurashige, O. Nishiyama, and S. Shinzaki; Osaka Kouseinenkin Hospital, M. Kurokawa and A. Uemura; National Osaka South Hospital, T. Oze and N. Tsuda; Kansai Rousai Hospital, T. Yoshio; Osaka Police Hospital, K. Koga; Osaka Prefectural Hospital, A. Arimitsu; and Osaka University Graduate School of Medicine, S. Yamaguchi, M. Miyazaki, H. Miyatake, I. Itose, S. Egawa, and T. Nishida. This work was supported by a Grant-in-Aid for Research on Hepatitis and BSE from the Ministry of Health Labour and Welfare of Japan, and Scientific Research from the Ministry of Education, Science, and Culture of Japan. References [1] Davis GL, Balart LA, Schiff ER, et al. Treatment of chronic hepatitis C with recombinant interferon alpha. A multicenter randomized controlled trial. N Engl J Med 1989;321:1501–6. [2] Di Bisceglie AM, Martin P, Kassianides C, et al. Recombinant interferon alpha therapy for chronic hepatitis C. A randomized, double blind placebo-controlled trial. N Engl J Med 1989;321:1506– 10. [3] Hiramatsu N, Hayashi N, Kasahara A, et al. Improvement of liver fibrosis in chronic hepatitis C patients treated with natural interferon alpha. J Hepatol 1995;22:135–42. [4] Kasahara A, Hayashi N, Mochizuki K, et al. Pretreatment viral load and response to interferon therapy for liver cirrhosis caused by hepatitis C virus: a multicenter controlled study. Hepatol Res 2000;16:124–38.
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[5] Kakumu S, Yoshioka K, Wakita T, et al. A pilot study of ribavirin and interferon beta for the treatment of chronic hepatitis C. Gastroenterology 1993;105:507–12. [6] Brillanti S, Garson J, Foli M, et al. A pilot study of combination therapy with ribavirin plus interferon alpha for alpha-interferon resistant chronic hepatitis C. Gastroenterology 1994;107: 812–7. [7] Lai MY, Kao JH, Yang PM, et al. Long-term efficacy of ribavirin plus interferon alfa in the treatment of chronic hepatitis C. Gastroenterology 1996;111:1307–12. [8] Bondenheimer Jr HC, Lindsay KL, Davis GL, et al. Tolerance and efficacy of oral ribavirin treatment of chronic hepatitis C: a multicenter trial. Hepatology 1997;26:473–7. [9] McHutchison JG, Gordon SC, Schiff ER, et al. Interferon alpha-2b and ribavirin as initial treatment of relapse of chronic hepatitis C. N Engl J Med 1998;339:1485–92. [10] Poynard T, Marcellin P, Lee SS, et al. Randomised trial of interferon alpha-2b and ribavirin for 48 weeks or for 24 weeks versus interferon alfa-2b plus placebo for 48 weeks for treatment of chronic infection with hepatitis C virus. Lancet 1998;352:1426–32. [11] Reichard O, Norkrans G, Fryden A, et al. Randomized double-blind, placebo-controlled trial of interferon alpha-2b with and without ribavirin for chronic hepatitis C. Lancet 1998;351:83–6. [12] Davis GL, Esteban-Mur R, Rustgi V, et al. Interferon alpha-2b alone or in combination with ribavirin for the treatment or relapse of chronic hepatitis C. N Engl J Med 1998;339:1493–9. [13] Consensus statement. EASL international consensus conference on hepatitis C. Paris, 26–28 February 1999. J Hepatol 1999;30: 956–61. [14] Bisceglie AM, Hoofnagle JH. Optimal therapy of hepatitis C. Hepatology 2002;36:S121–7. [15] Kasahara A, Hayashi N, Hiramatsu N, et al. Ability of prolonged interferon treatment to suppress relapse after cessation of therapy in patients with chronic hepatitis C: a multicenter randomized controlled trial. Hepatology 1995;21:291–7. [16] Yuki N, Hayashi N, Kasahara A, et al. Pretreatment viral load and response to prolonged interferon-␣ course for chronic hepatitis C. J Hepatol 1995;22:457–63. [17] Lau YN, Davis G, Kniffen J, et al. Significance of serum hepatitis C virus RNA levels in chronic hepatitis C. Lancet 1993;341:1501–4. [18] Shiratori Y, Kato N, Yokosuka O, et al. Predictors of the efficacy of interferon therapy in chronic hepatitis C virus infection. Gastroenterology 1997;113:558–66. [19] Hagiwara H, Hayashi N, Mita E, et al. Quantitative analysis of hepatitis C virus RNA in serum during interferon alfa therapy. Gastroenterology 1993;104:877–83. [20] Tanaka T, Tsukiyama-Kohara K, Yamaguchi K, et al. Significance of specific antibody assay for genotyping of hepatitis C virus. Hepatology 1994;19:1347–53. [21] Knodell RG, Ishak KG, Black WC, et al. Formulation and application of a numerical scoring system for assessing histological activity in asymptomatic chronic active hepatitis. Hepatology 1981;1:431–5. [22] Poynard T, Marcellin P, Lee SS, et al. Randomized trial of interferon ␣2b plus ribavirin for 48 weeks or for 24 weeks versus ineterferon ␣2b plus placebo for 48 weeks for treatment of chronic infection with hepatitis C. Lancet 1998;352:1426–32. [23] Poynard T, McHutchison J, Goodman Z, et al. Is an “A la Carte” combination interferon alfa-2b plus ribavirin regimen possible for the first line treatment in patients with chronic hepatitis C? Hepatology 2000;31:211–8. [24] Pol S, Nalpas B, Bourliere M, et al. Combination of Ribavirin and interferon-alfa surpasses high doses of interferon-alfa alone in patients with genotype-1b-related chronic hepatitis C. Hepatology 2000;31:1338–44.
The significance of interferon and ribavirin combination therapy followed by interferon monotherapy for patients with chronic hepatitis C in Japan Naoki Hiramatsu a , Akinori Kasahara b , Fumihiko Nakanishi c , Takashi Toyama c , Masahiko Tsujii c , Shingo Tsuji c , Tatsuya Kanto a , Tetsuo Takehara a , Michio Kato d , Harumasa Yoshihara e , Masafumi Naito f , Kazuhiro Katayama f , Taizo Hijioka g , Hideki Hagiwara h , Shinji Kubota i , Masahide Oshita j , Haruya Meren j , Manabu Masuzawa j , Yoshimichi Haruna k , Eiji Mita l , Kunio Suzuki l , Norio Hayashi a,∗ a
Department of Molecular Therapeutics, Osaka University Graduate School of Medicine, 2-2, Yamadaoka, Suita City, Osaka 565-0871, Japan b Department of General Medicine, Osaka University Graduate School of Medicine, Osaka, Japan c Department of Internal Medicine and Therapeutics, Osaka University Graduate School of Medicine, Osaka, Japan d Osaka National Hospital, Osaka, Japan e Osaka Rousai Hospital, Osaka, Japan f Osaka Kouseinenkin Hospital, Osaka, Japan g National Osaka South Hospital, Osaka, Japan h Higashiosaka City Central Hospital, Osaka, Japan i Kansai Rousai Hospital, Hyoga, Japan j Osaka Police Hospital, Osaka, Japan k Osaka Prefectural Hospital, Osaka, Japan l Saiseikai senri Hospital, Osaka, Japan Received 26 December 2003; received in revised form 16 March 2004; accepted 25 March 2004
Abstract One hundred seventy-one patients with chronic hepatitis C were included in this study (genotype1 and high viral loads (1H), n = 130; non-1H, n = 37; N.D., n = 4). The combination therapy of interferon and ribavirin for 24 weeks with an additional 24 weeks of interferon monotherapy (48-week treatment) was undergone by 42 1H patients and 5 non-1H patients. The combination therapy of interferon and ribavirin was administered for 24 weeks in 67 1H patients and 22 non-1H patients. Among the 1H patients, the HCV relapse rate was significantly higher in those receiving 24-week combination treatment than in those receiving 48-week treatment (78% versus 42%, P = 0.003). Among the non-1H patients, no significant difference was found between them. Sustained virological response (SVR) rates were observed to decrease as the timing of HCV RNA disappearance was delayed. In spite of the small rate (16%), SVR was obtained from the patients who became negative for HCV RNA by week 24 (beyond week 12) only in those receiving 48-week treatment. In 1H patients, 24-week combination treatment followed by interferon monotherapy for 24 weeks was concluded to be the treatment offering the most hope among those that the medical insurance can be applied in Japan. © 2004 Published by Elsevier B.V. Keywords: Chronic hepatitis C; Interferon and ribavirin combination therapy; Combination therapy followed by IFN monotherapy
1. Introduction Interferon is the only available treatment for patients with chronic hepatitis C since HCV was discovered in ∗ Corresponding author. Tel.: +81-6-6879-3441; fax: +81-6-6879-3449. E-mail address: [email protected] (N. Hayashi).
1386-6346/$ – see front matter © 2004 Published by Elsevier B.V. doi:10.1016/j.hepres.2004.03.008
1989 [1–4]. Thirty percent of patients with chronic hepatitis C achieved SVR by interferon therapy but the efficacy was not satisfactory. Furthermore, in the patients considered to be the most treatment-resistant, that is, the 1H patients, only 5–8% showed SVR. In Japan, 40–50% of the patients with chronic hepatitis C belong to the 1H group. Therefore, finding how to eradicate the HCV RNA
N. Hiramatsu et al. / Hepatology Research 29 (2004) 142–147
of 1H patients is most important for the treatment of chronic hepatitis C. Recently, ribavirin, a nucleic acid analogue, exhibiting in vitro activity against various kinds of DNA and RNA viruses has been developed. The combination therapy of ribavirin and interferon has been shown to be very useful in the eradication of HCV in patients with chronic hepatitis C [5–7], although the mechanism of action of ribavirin remains speculative and ribavirin monotherapy led to no significant decrease of the amount of HCV RNA in the patients with chronic hepatitis C [8]. Most recent studies, performed with large numbers of na¨ıve patients, have shown that the combination therapy of interferon and ribavirin can increase the SVR rate two-fold compared with interferon monotherapy for patients with chronic hepatitis C [9–12]. Especially, in the 1H patients, the combination therapy of interferon and ribavirin was more useful than in the other patients. Furthermore, Poynard et al. [10] showed that 1H patients treated by combination therapy for 48 weeks had a higher SVR rate than those treated for 24 weeks (28% versus 8%). Therefore, the combination therapy of interferon and ribavirin for 48 weeks is recommended as the standard therapy for 1H patients in Europe and the United States [13,14]. In Japan, the combination therapy of interferon and ribavirin was approved in 2001. However, the duration of the combination therapy is limited to 24 weeks in the medical insurance. As mentioned above, the SVR rate in 1H patients treated by the combination therapy for 24 weeks was clearly lower than those treated for 48 weeks. Furthermore, prolonged interferon monotherapy was reported to suppress relapse after cessation of therapy and to achieve a higher SVR rate in patients with chronic hepatitis C [15]. This study assessed the efficacy of the combination therapy of interferon and ribavirin for 24 weeks with an additional 24 weeks of interferon monotherapy compared with that of the combination therapy for 24 weeks.
2. Patients and methods 2.1. Patients The current study was conducted at Osaka University Hospital and the institutions of the Osaka Liver Disease Study Group. The 171 patients included in this study had HCV RNA detectable in serum by the polymerase chain reaction (PCR) method, had elevated ALT (above the upper limit of the normal) and had been histologically proven to have chronic hepatitis. No patients were positive for hepatitis B surface antigen and anti-human immunodeficiency virus antibody or had other forms of liver disease (such as alcoholic liver disease and autoimmune liver disease). This study protocol was carried out according to the ethical guidelines of the 1975 Declaration of Helsinki and informed consent was obtained from each patient.
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2.2. Determination of HCV RNA levels and HCV genotype Serum HCV RNA levels were quantified using branched DNA (bDNA) probe assay (version 2; Chiron, Dai-ichi Kagaku, Tokyo) [16,17] or combined PCR assay (AmplicorHCV monitor assay) [18]. In this study, a high viral load, as described previously [16,18,19], was designated as the condition of a serum HCV RNA level of more than 106 equivalents/ml by bDNA assay or more than 105 copies/ml serum by Amplicor-HCV monitor assay. HCV genome typing was classified by serological genotyping assay [20]. 2.3. Treatment schedule Of the 171 patients with chronic hepatitis C enrolled in this study, 130 had HCV RNA with genotype 1 and high viral loads (1H group), which were difficult to eradicate by anti-viral therapy. Of the remaining 41 patients, 37 had HCV RNA with genotype 2 or low viral loads (non-1H group); genotype or viral levels could not be determined for four. One hundred thirty-six patients in whom treatment had been done without the discontinuation of interferon till the end of the scheduled duration were studied (1H, n = 109; non-1H, n = 27). The combination therapy of interferon-␣-2b and ribavirin was administered for 24 weeks in 67 patients of the 1H group and 22 patients of the non-1H group. In this protocol, interferon-␣-2b was given intramuscularly every day for the first 2 weeks and then three times a week for the following 22 weeks in combination with ribavirin at a daily dose of 600 or 800 mg, depending on body weight (<60 or ≥60 kg, respectively). The combination therapy of interferon-␣-2b and ribavirin for 24 weeks, followed by interferon-␣-2b monotherapy three times a week for a further 24 weeks, was administered to 42 patients of the 1H group and 5 patients of the non-1H group. The pretreatment characteristics of the patients were similar (Table 1). The starting doses of interferon-␣-2b were 10 MU per day for 38, 6 MU per day for 127, and 3 MU per day for 6 patients. With ribavirin, 800 mg per day was started in 92, 600 mg per day in 77, and 400 mg per day in 2 patients. Among the 171 patients, the interferon dose was decreased in six patients during the treatment, and the interferon was stopped along with ribavirin in 33 patients (19%) due to side effects. The ribavirin dose was decreased in 43 patients (25%) during the treatment, and stopped without discontinuance of interferon in six patients. Eighty-seven patients (51%) completed treatment without discontinuance or dosage decrease of both drugs. After the sufficient informed consent at the end of the combination therapy of interferon and ribavirin, the patients themselves decided whether to be treated for 24 or 48 weeks. The information included the results of clinical trials of the combination therapy for 24 and 48 weeks in other countries, such as the SVR rate, HCV relapse rate.
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Table 1 Baseline characteristics of patients according to therapeutic protocol 24-week treatment
Age (yo) M/F ALT (IU/L) Fibrosis
1H group
Non-1H group
48-week treatment 1H group
67 55.8 ± 10.9 40/27 107 ± 71 1.9 ± 0.9
22 55.7 ± 12.8 15/7 102 ± 45 1.9 ± 1.2
42 54.0 ± 11.7 28/14 103 ± 58 1.8 ± 1.1
History of IFN treatment Na¨ıve 34 Relapser 21 Non-responder 11 Unknown 1
11 7 4 0
17 17 8 0
Note: All comparisons are not significant. Twenty-four-week treatment, interferon plus ribavirin treatment for 24 weeks; 48-week treatment, interferon plus ribavirin treatment for 24 weeks followed by interferon monotherapy for 24 weeks. 1H group, patients with genotype 1 and high viral load; non-1H group, patients other than 1H group. Fibrosis, Knodell’s histological score (category 4).
Also, side effects were presented and the combination therapy of interferon-␣-2b and ribavirin for 48 weeks was explained as not being covered by medical insurance in Japan. In the 47 patients who agreed to receive the additional 24 weeks of interferon monotherapy, the starting doses of interferon-␣-2b were 10 MU per day for 10, 6 MU per day for 35, and 3 MU per day for 2 patients. All patients completed the additional treatment although interferon was decreased only in one patient from 10 to 6 MU per day. 2.4. Statistical analysis Age, histological scores before interferon therapy, and serum ALT levels are expressed as mean ± S.D. The chi-squared test was used for statistical analysis of the comparison between group frequencies. When appropriate, the clinical and laboratory features of the two groups were compared by Student’s t-test. Histological evaluation was
substituted as a variable for Knodell’s histological scores [21]. 3. Results 3.1. Results of interferon and ribavirin combination therapy Seventy-five percent of all of the patients of 1H group (82/109), including not only patients who received 24-week treatment but also those who received 48-week treatment, had no detectable HCV RNA at 24 weeks after the beginning of combination therapy of interferon and ribavirin. This was also the case for 100% of the non-1H patients (27/27). In patients given 24-week treatment of combined interferon and ribavirin, 45 out of 67 of the 1H group were negative for HCV RNA at the end of therapy, but only 22% of the patients (10/45) showed no detectable HCV RNA at 24 weeks after cessation of therapy. On the other hand, HCV RNA was negative in all non-1H patients at the end of the 24-week treatment, and the SVR rate was 86% (19/22) (Fig. 1). In patients with 48-week treatment (24-week combination treatment, followed by 24-week interferon monotherapy), HCV RNA reappeared during interferon monotherapy (break through) in 11 out of 37 patients (30%) who were negative for HCV RNA at the end of 24-week combination therapy: SVR was finally reached in 15 out of 26 patients who continued to be sero-negative for HCV RNA at the end of 48-week treatment. On the other hand, HCV RNA was not cleared even by 48-week treatment in all five patients who were positive for HCV RNA at the end of 24-week treatment (Fig. 2). In the non-1H patients who received 48-week treatment, HCV RNA was negative in all five patients at the end of the 24-week treatment, and SVR was attained by 80% (4/5). The HCV RNA relapse rate after treatment was compared according to the duration of treatment. In all patients, 57% of those receiving 24-week treatment (38/67) had HCV RNA relapse, as compared with 39% of those receiving 48-week treatment (12/31). Among the 1H patients, a significant dif-
24wks (EOT) HCV (-) n=45
1H
HCV (-) n=10
n=67 HCV (+) n=35
SVR = 0% 0/22
HCV (+) n=22
Non-1H
Relapse rate = 78% 35/45
n=22
HCV (-) n=22
HCV (-) n=19
SVR = 86% 19/22
HCV (+) n=3
Fig. 1. Efficacy of the combination therapy (24-week treatment). 1H group, patients with genotype 1 and high viral load; non-1H group, patients other than those of the 1H group. EOT, end of treatment. HCV, serum HCV RNA positivity by polymerase chain reaction.
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48wks (EOT)
24wks
RNA (-) n=37
1H
n=42
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RNA (-) n=15
RNA (-) n=26
RNA (+) n=11
RNA (+) n=11
Relapse rate = 42% 11/26
SVR = 0% 0/11
BT = 30% 11/37 SVR = 0% 0/5
RNA (+) n=5
Fig. 2. Efficacy of the combination therapy followed by interferon monotherapy (48-week treatment). 1H group, patients with genotype 1 and high viral load; non-1H group, patients other than those of the 1H group. EOT, end of treatment. HCV, serum HCV RNA positivity by polymerase chain reaction. BT, break through.
The relationship between the timing of HCV RNA disappearance and SVR rate according to the duration of treatment was evaluated. As shown in Fig. 3A, in all patients receiving 24-week treatment, 71% (12/17) of the patients who had no detectable HCV RNA by week 4, 61% (11/18) by week 8 (beyond week 4), and 21% (4/19) by week 12 (beyond week 8) had SVR. Although 11 patients became negative for HCV RNA by week 24 (beyond week 12), none of them attained SVR. A tendency for a decrease in the SVR rate was observed as the timing of the HCV RNA disappearance was delayed. In the patients receiving 48-week treatment, 86% (6/7) of those who had no detectable HCV RNA by week 4, 100% (6/6) by week 8 (beyond week 4), 40% (4/10) by week 12 (beyond week 8), and 16% (3/19) by week 24 (beyond week 12) attained SVR. Among the 1H patients, the same tendency was also observed (Fig. 3B). In the patients receiving 24-week treatment, 50% (3/6) of those who had no detectable HCV RNA by week 4, 40% (4/10) by week 8 (beyond week 4), and 18% (3/17) by week 12 (beyond week 8) attained SVR. None of the 10 patients who became negative for HCV RNA by week 24 (beyond week 12) showed SVR. In the patients receiving 48-week treatment, 80% (4/5) of those who had no detectable HCV RNA by week 4, 100% (5/5) by week 8 (beyond week 4), 38% (3/8) by week 12 (beyond week 8), and 16% (3/19) by week 24 (beyond week 12) had SVR. In spite of the small rate (16%), SVR was obtained from the patients
1 00
100 80 SVR rate (%)
3.2. Timing of HCV RNA disappearance and efficacy of treatment
who became negative for HCV RNA by week 24 (beyond week 12) only in those receiving 48-week treatment. Fig. 4 shows the relationship between the timing of HCV RNA disappearance and the prediction value in 1H patients who received the combination therapy of interferon and ribavirin for 24 weeks. As the timing of the HCV RNA disappearance was late, the positive prediction value decreases and the negative prediction value increases. In particular, the negative prediction value at week 12 was 100%, that is, none
86 71 61
60 40 40 21
16
20 0 0 week 4
(A)
week 8 week 12 week 24 Timing of HCV RNA disappearance 1 00
100 80 80 SVR rate (%)
ference was found in HCV relapse rate between those receiving 24-week treatment and those receiving 48-week treatment (78% versus 42%, P = 0.003). Among the non-1H patients, HCV RNA relapsed in 14% (3/22) of those receiving 24-week treatment (Fig. 1) and 20% (1/5) of those receiving 48-week treatment.
60
50 40
38
40 20
18
16 0
0
(B)
week 4 week 8 week 12 week 24 Timing of HCV RNA disappearance
Fig. 3. Timing of HCV RNA disappearance and SVR rate (A) all patients, (B) patients with genotype 1 and high viral loads. (ⵦ) Combination therapy of interferon and ribavirin (24-week treatment); ( ) combination therapy followed by interferon monotherapy (48-week treatment).
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Predictive value (%)
100 80 60 40 20 0 4W
8W
12W
24W
Timing of HCV RNA disappearance Fig. 4. Timing of HCV RNA disappearance and prediction value in patients with genotype 1 and high viral loads who received the combination therapy of interferon and ribavirin for 24 weeks. (ⵦ) Positive prediction value; ( ) negative prediction value; ( ) predictive accuracy.
of the patients who were positive for HCV RNA at week 12 attained SVR.
4. Discussion In Japan, randomized control studies were performed on the combination therapy of interferon and ribavirin for 24 weeks in patients with chronic hepatitis C, and the combination therapy was approved in November 2001. However, the duration of the combination therapy is limited to 24 weeks in the medical insurance because of the lack of clinical mega-trial evidence for the combination therapy for 48 weeks in Japan. From the results of international trials, the SVR rate in 1H patients treated by the combination therapy for 48 weeks has been shown to be higher than that of those treated for 24 weeks [10]. Moreover, for interferon monotherapy, prolonged interferon treatment was reported to suppress relapse after cessation of therapy and to lead to a higher SVR rate in patients with chronic hepatitis C [15]. Our strategy, the interferon and ribavirin combination therapy with an additional 24 weeks of interferon monotherapy, was conducted against this background. Poynard et al. [22,23] evaluated the HCV RNA relapse rates after cessation of the combination therapy in na¨ıve patients with chronic hepatitis C. Among patients with genotype 1, the relapse rates were 62% in those treated by interferon and ribavirin combination therapy for 24 weeks and 26% in those treated for 48 weeks: among patients with genotype 2/3, 21% in those for 24 weeks and 15% in those for 48 weeks. Among patients with genotype 1, the SVR rate increased due to suppression of the relapse rate by the combination therapy for 48 weeks. On the other hand, the patients with genotype 2/3 require only 24 weeks of therapy. In our study, patients with genotype 1 and high viral load (1H group) were evaluated, distinguishing them from others (non-1H group) since the efficacy of anti-viral therapy for the 1H patients has been known to be remarkably low. Among the 1H patients, the HCV relapse rate
was significantly higher in those receiving 24-week combination treatment than in those receiving 48-week treatment, 24-week combination treatment followed by interferon monotherapy for 24 weeks (78% versus 42%, P = 0.003). Among the non-1H patients, no significant difference was found between those receiving 24-week treatment and those receiving 48-week treatment (14% versus 20%). These results indicate that our strategy of 48-week treatment is useful for the 1H group; the non-1H group seems to require only 24 weeks of therapy, similar to the patients with genotype 2/3 in the above-mentioned. In the 1H patients receiving 48-week treatment, HCV RNA reappeared during interferon monotherapy in 11 out of 37 patients (30%) who were negative for HCV RNA at the end of 24-week combination therapy. The break through phenomenon should be taken into account when the efficacy of this treatment is evaluated. The SVR ratio in 1H patients receiving 48-week treatment can be calculated from the prevalence of undetectable HCV RNA at 24 weeks after the beginning of combination therapy of interferon and ribavirin (75%, 82/109), of break though (30%, 11/37) and of HCV relapse rate (42%, 11/26); the expected SVR is 30% ((82/109) × (1 − (11/37)) × (1 − (11/26)) 0.30). In the same manner, the SVR ratio in 1H patients receiving 24-week treatment is expected to be 17% (82/109) × (1 − (35/45)) 0.17. In 1H patients, 48-week treatment, 24-week combination treatment followed by interferon monotherapy for 24 weeks, may be the useful treatment which can be actually performed in Japan. The relationship between the timing of HCV RNA disappearance and the SVR rate according to the duration of treatment was evaluated. SVR rates decreased with a delay in the timing of HCV RNA disappearance in patients receiving 24-week treatment; the negative prediction value at week 12 was 100%, that is, none of the patients who were positive for HCV RNA at week 12 had SVR. In spite of the small rate (16%), SVR was attained for patients who became negative for HCV RNA by week 24 (beyond week 12) only in those receiving 48-week treatment. Accordingly, treatment withdrawal should be offered to patients who remain HCV RNA-positive after 12 weeks of therapy if the patient cannot continue treatment for 48 weeks for reasons including side effects and social issues. The patients who were positive for HCV RNA at week 24 should stop treatment because additional interferon monotherapy for 24 weeks could not clear HCV RNA in all five patients who were positive for HCV RNA at week 24. Pol et al. [24] have reported the synergistic effect of ribavirin and interferon in 343 patients with the genotype 1b. In the study, ribavirin was administered for 4, 6, 12 months in combination with interferon-␣ for 12 months. A 12-month course of ribavirin achieved significantly greater virological efficacy than 6 or 4 months at the end of the 12-month course of interferon-␣ (59, 49, and 29%), the same trend seen at the end of follow-up duration (43, 36, and 21%). These results indicate that the maximum efficacy can be obtained
N. Hiramatsu et al. / Hepatology Research 29 (2004) 142–147
when ribavirin is administered for 12 months in combination with interferon. In our study, the break through ratio was expected to decrease with the administration of ribavirin for 48 weeks. In fact, a patient to whom ribavirin was given again after the break through, achieved marked decrease of HCV RNA (data not shown). Thus, in some patients who were negative for HCV RNA during the combination treatment, the additional ribavirin can be essential for eradicating HCV RNA. Longer duration of combination therapy with interferon and ribavirin is also most effective for suppressing HCV RNA relapse after 24 weeks of therapy [22,23]. Therefore, we would like to emphasize that combination therapy of ribavirin and interferon for 48 weeks should be permitted even in Japan. At present, 24-week combination therapy followed by 24-week interferon monotherapy is thought to be the most useful therapy that the medical insurance can be applied in Japan for suppressing the relapse rate of HCV RNA, leading to SVR. Acknowledgements In addition to the study authors, the following institutions and physicians were participants in the Osaka Liver Disease Study Group (Digestive Disease Study Group of Osaka Renaissance): Osaka National Hospital, R. Sakamori; Osaka Rousai Hospital, N. Kurashige, O. Nishiyama, and S. Shinzaki; Osaka Kouseinenkin Hospital, M. Kurokawa and A. Uemura; National Osaka South Hospital, T. Oze and N. Tsuda; Kansai Rousai Hospital, T. Yoshio; Osaka Police Hospital, K. Koga; Osaka Prefectural Hospital, A. Arimitsu; and Osaka University Graduate School of Medicine, S. Yamaguchi, M. Miyazaki, H. Miyatake, I. Itose, S. Egawa, and T. Nishida. This work was supported by a Grant-in-Aid for Research on Hepatitis and BSE from the Ministry of Health Labour and Welfare of Japan, and Scientific Research from the Ministry of Education, Science, and Culture of Japan. References [1] Davis GL, Balart LA, Schiff ER, et al. Treatment of chronic hepatitis C with recombinant interferon alpha. A multicenter randomized controlled trial. N Engl J Med 1989;321:1501–6. [2] Di Bisceglie AM, Martin P, Kassianides C, et al. Recombinant interferon alpha therapy for chronic hepatitis C. A randomized, double blind placebo-controlled trial. N Engl J Med 1989;321:1506– 10. [3] Hiramatsu N, Hayashi N, Kasahara A, et al. Improvement of liver fibrosis in chronic hepatitis C patients treated with natural interferon alpha. J Hepatol 1995;22:135–42. [4] Kasahara A, Hayashi N, Mochizuki K, et al. Pretreatment viral load and response to interferon therapy for liver cirrhosis caused by hepatitis C virus: a multicenter controlled study. Hepatol Res 2000;16:124–38.
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