J Gastroenterol 1995; 30:485-492
Journal of
Gastroenterology I 9 Springer-Verlag 1995
Efficacy of combination therapy with interferon and azidothymidine in chronic type C hepatitis: A pilot study MIKIHIRO TSUTSUMI, AKIRATAKADA, and MAKOTO SAWADA Division of Gastroenterology, Department of Internal Medicine, Kanazawa Medical University, Uchinada, Ishikawa, 920-02Japan
Abstract: The
effects of interferon are seen in only a limited number of patients with hepatitis C virus (HCV) of the K1 type, indicating that a combination therapy with other antiviral drugs may be essential to obtain better results. In the present pilot study, the effects of combination therapy with interferon (IFN) and an antiviral drug azidothymidine (AZT) were analyzed. The combination therapy was conducted in 22 patients with chronic hepatitis C after obtaining their informed consent (combination group). Three or six million units of natural IFN alpha was administered daily for 3 weeks and then three times a week for 21 weeks. Combination therapy was initiated at the beginning of the 8th week of IFN treatment, 500 mg of AZT per day being given for 8 weeks. As a control, changes in HCV-RNA were also analyzed in patients treated with interferon alone (IFN-alone group). At the end of the treatment, blood was negative for HCV in 32.5% of the IFN-alone group and in 50.0% of the combination group, the difference not being significant. However, in patients with HCV-K1, HCVnegative rates were 14.2% in the IFN-alone group and 45.5% in the combination group, showing a significant difference. In patients with other HCV genotypes, HCV-negative rates did not different between the two groups. These results suggest that combination therapy with IFN and AZT may be an effective treatment for chronic type C hepatitis caused by the K1 type virus, although further studies on larger number of patients will be needed to obtain definite conclusions.
Key words: hepatitis C virus (HCV),
interferon (IFN), azidothymidine (AZT), combination therapy with IFN and A Z T
Offprint requests to: A. Takada (Received for publication on Sept. 19, 1994; accepted on Dec. 16, 1994)
Introduction Interferon (IFN) is now commonly used for the treatment of type C hepatitis. However, results vary, with IFN being reported to. be effective in fewer than half of the patients treated. 1-1~ The variable effects of IFN may be related to many factors. For example, its effectiveness differs depending on the hepatitis C virus (HCV) genotype. 5-1~ In patients with HCV of the type K1 (HCV-K1), a complete response following IFN treatment was observed in only a limited number of patients (fewer than 250/0).5-1~ We have reported that the effects of IFN may depend on the response of individual patients to HCV, since the final effect of IFN was not related to the time at which HCV-RNA encoding the NS5 region disappeared from the blood during IFN treatment. 6 These findings may be related to the virustatic, but not virucidal, effects of IFN. Recently, the development of HCV mutants that escape neutralizing antibodies was confirmed by Enomoto et al., 11 and the possibility of.the development of IFN-resistant strains of HCV during IFN treatment has also been reported. 12'13 The easy development of HCV mutants may also be related to the response of individual patients to HCV. These results indicate that a combination therapy of IFN with other antiviral drugs may be essential if better results are to be obtained in patients with HCV-K1. Azidothymidine (AZT) is an antiviral drug used for the treatment of HIV infection. Vento et al. 14 reported briefly that HCV marker-positive patients with AIDS treated with AZT showed improvement in the clinical and histological features of chronic type C hepatitis, but not in the symptoms of AIDS. Both HCV and HIV are RNA viruses. These results suggest that AZT may be an effective agent for the treatment of HCV infection. In a preliminary study, 15 we found that the titer of HCV in blood, and levels of serum transaminase activity, were clearly decreased by the
486
M. Tsutsumi et al.: Combination therapy with IFN and AZT
administration of 500mg of AZT for 4-8 weeks in four patients with chronic type C liver disease, and a combination treatment with IFN and AZT was effective in two patients. These results indicate that AZT is effective for HCV infection, and in the present pilot study, we analyzed the effects of a combination therapy with IFN and AZT.
HCV-antibodies (HCV-Ab) were determined using second generation test kits. 16 HCV-RNA encoding the NS5 region (HCV-NS5) was detected via the reverse transcription-polymerase chain reaction (RT-PCR), as reported previously. ~7,~s HCV genotypes were determined using type-specific eDNA probes, as reported previously. 19,z~ The PT, K1, K2a, and K2b types in the present study were compatible with the la, lb, 2a, and 2b types, respectively, according to the classification of Simmonds et al. 21 When HCV-NS5 was negative, HCV-RNA encoding the 5'-noncoding region (HCV-5'NC) was detected by two-stage PCR, carried out according to the description given by Okamoto et al. 22 When HCV-5'NC was negative, blood HCV-RNA was regarded as negative. The titers of HCV in blood were determined by multicyclic PCR and slot-blot hybridization, as described by Ishiyama et al. 23 Examinations for HCV, except for the genotyping of HCV, were performed before and after the administration of IFN and AZT. Routine hepatic tests, including measurement of serum alanine and aspartate transaminase (ALT and AST) activity, were made sequentially once a week or every 2 weeks. Blood cell analysis was also performed sequentially during AZT administration. The response of serum ALT level to the treatment was evaluated by previously reported criteria5 at the end of the 15th and 24th week of treatment, both in the IFN-alone and the combination groups. "No response" was defined as only a slight decrease or no decrease of ALT level (less than 50% of pre-therapeutic levels). "Partial response" was defined as a decrease of more than 50% of the pre-therapeutic value without normalization. "Good response" was defined as a decrease in the upper limit of the normal range (less than 50 units). Histological findings in liver biopsy specimens obtained before and after treatment were compared in 12 patients in the combination group. Chronic hepatitis activity was evaluated with the histological activity index (HAI) system described by Knodell et al. 24 As a control, changes of HCV-RNA were analyzed retrospectively in 35 patients with chronic active type C hepatitis who were treated in the same manner with 3 or 6 MU of various types of IFN for 24 weeks (IFNalone group). For the stat~shcai anaiysi~ of group comparisons, Student's t test or the chi square test was used. Experimental values were expressed as means + SD. A probability value of 0.05 by the one-tailed test was considered statistically significant.
Materials and methods
Initially, the administration of IFN and AZT was begin in 30 patients with chronic type C hepatitis. However, the administration of AZT had to be discontinued within 4 weeks in 8 patients because of adverse reactions to AZT (AZT-discontinued group). Consequently, combination therapy with IFN and AZT was conducted in 22 patients with chronic active type C hepatitis (combination group). Informed consent was obtained from all patients before treatment. The diagnosis of each patient was confirmed histologically. Three or 6 million units (MU) of natural IFN alpha (Sumiferon; Sumitomo Pharmaceuticals Co Ltd., Osaka, Japan) was administered intramuscularly to each patient daily for 3 weeks, the dose being determined according to the patient; administration was then continued three times a week for 21 weeks. For 7 weeks of treatment with IFN alone, observations were made of the basal changes that occurred with this treatment, At the beginning of the 8th week, combination treatment with AZT was initiated. One hundred mg of AZT (Retrovir; Sumitomo Pharmaceuticals Co Ltd., Osaka, Japan) was given orally at 4h intervals, except during the night, when one dose was omitted (i.e., the dose of AZT was 500rag per day), and administration was continued for 8 weeks. After the completion of AZT administration, IFN alone was administered three times a week for a further 9 weeks. The schedule of combination treatment with IFN and AZT is shown in Fig. 1. Twenty-two patients in the combination group were treated according to this schedule. In the 8 patients in the AZTdiscontinued group, IFN administration was continued until the end of the 24th week after AZT administration had ceased.
0
3
7
15
24( !~ee]~ }
Fig, 1, Schedule of combination therapy with interferon
(IFN) and azidothymidine (AZT)
M. Tsutsumi et al.: Combination therapy with IFN and A Z T
Results In the 16 of 22 patients in the combination group in whom H C V genotypes were determined, the genotype was K1 in 11 patients, K2a in 2 patients, K2b in 2 patients, and PT in 1 patient. In the remaining 6 patients, H C V genotypes were not determined (unclassified group), because only H C V - 5 ' N C was positive before treatment. HCV-NS5 was negative in many patients upon the daily administration of IFN for 3 weeks. However, H C V - 5 ' N C was positive in all patients before the commencement of A Z T administration (at the end of the 7th week of the IFN treatment). The changes of H C V - R N A in each patient in the combination group are shown in Table 1. O n the administration of A Z T for 8 weeks, H C V - 5 ' N C was negative in 13 patients. Although IFN treatment was continued until the 24th week, H C V - 5 ' N C had again become positive in 3 patients at the end of treatment. On the other hand, one HCV-5'NC-positive patient was negative by the end of treatment. Finally, H C V 5 ' N C was negative in 11 patients at the end of treatment. In 6 of the 11 patients with HCV-K1, H C V - 5 ' N C was negative with A Z T administration. However, H C V - 5 ' N C was positive again in 1 patient by the end of treatment, leaving 5 HCV-5'NC-negative patients
487 at the end of treatment. In the 5 patients with other types of H C V , H C V - 5 ' N C was negative in 4 patients at the end of the A Z T administration, and negative in 3 patients at the end of treatment. Of the 6 patients in the unclassified group, H C V - 5 ' N C was negative in 3 at the end of the A Z T administration. In this group, H C V - 5 ' N C was positive again in 1 patient and negative in 1 patient by the end of treatment, leaving 3 HCV-5'NC-positive patients at the end of treatment. A L T responses at the end of treatment were good in 10 of the 11 patients who were negative for HCV5'NC. On the other hand, of the 11 patients who were positive for H C V - 5 ' N C , the A L T response was good in only 5 patients. A dose of 6 MU of IFN was administered to 7 patients in the K1 group and to 5 patients in the other group, in which the 6 unclassified cases were included; 3 M U of IFN was administered to 4 patients in the K1 group and to 6 patients in the other group. In the K1 group, H C V - R N A disappeared from the blood in 4 of the 7 patients treated with 6 M U of IFN and in 1 of the 4 patients treated with 3 M U of IFN. In the other group, H C V - R N A disappeared from the blood in 3 of 5 patients treated with 6 M U of IFN and in 3 of 6 patients treated with 3 MU of IFN. Of the 13 patients in whom the histological activity, index (HA1) was examined before and after
Table 1. Effects of combination therapy with IFN and AZT on HCV-RNA in combination group HCV-5' NC HCV Case no. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 2t. 22.
Sex/Age
Diagnosis
IFN (MU)
Type
Titer ~
B-AZT (7 weeks)
A-AZA (15 weeks)
A-IFN (24 weeks)
M/43 M/66 M/44 F/22 M/57 M/38 M/28 M/20 M/42 M/47 F/29 M/31 M/56 M/28
CAH CAH CAH CAH CAH CAH CAH CAH CAH CAH CAH CAH CAH CAH CAH CAH CAH CAH CAH CAH ,~ Au ~.~i~ CAH
3 6 3 3 6 6 3 6 6 6 6 6 3 6 0 3 6 3 3 3 ,,c 3
K1 K1 K1 K1 K1 K1 K1 K1 K1 K1 K1 K2a K2a K2b K2b PT UC UC UC UC UC UC
10 8 8 10 6 9 8 10 7 9 8 9 7 10 ~ 9 10 7 10 7 "7 , 10
+ + + + + + + + + + + + + + ~ + + + + + + +
+ + + + + + + + + -
+ + + + + + + + -
F/52
F/36 F/52 F/57 M/42 F/20 M/26 M/18
+ + + -
ALT response (24 weeks) Poor Partial Partial Good Poor Poor Good Partial Good Good Good Good Poor Good Good Good Good Good Good Good Good Good
HAI score B
A
10 10
8 6
6
4
10
3
10 8 7
8 6 10
10 10
6 5
6 4 2
4 1 1
CAH, Chronic active hepatitis; UC, unclassified; MU, mega unit; B, before; A, after; HA1, histological activity index; IFN, interferon; HCV, hepatitis C virus; AZT, azidothymidine "10" copies/mt
488
M. Tsutsumi et al.: Combination therapy with IFN and AZT
treatment, the H A I scores were decreased in all patients, except for 1 whose A L T response was poor. The decrease in the H A I score was prominent in patients who were negative for H C V - 5 ' N C at the end of treatment. In 4 of the 7 patients in this group, the H A l scores after treatment were less than half of those before treatment. H o w e v e r , such a decrease was not found in the 5 patients who were positive for H C V - 5 ' N C at the end of treatment. The adverse side effects of A Z T observed in the original 30 patients are shown in Table 2. In 8 patients, the administration of A Z T had to be stopped because of the severity of side effects; the administration of A Z T was stopped within 4 weeks in 5 patients, and
within 3 weeks in 3 patients. The side effects shown in Table 2 were found in 16 of the 22 patients (72.7%) in the combination group. Severe bone marrow suppression was found in 3 patients. In the patients in w h o m the administration of A Z T had to be stopped, all side effects disappeared after A Z T was discontinued and the administration of I F N was continued until the end of the 24th week. In this group, H C V - 5 ' N C was negative in 3 patients with A Z T administration, but was positive again in 1 patient after A Z T administration was stopped. Since the period of A Z T administration was very short in this group, the changes in H C V R N A m a y have been caused predominantly by IFN alone. Therefore, the results in the AZT-discontinued group were included in the results of the IFN-alone group in the following analysis. Changes in H C V - R N A in the 43 patients in the IFN-alone group, which included 8 patients in the AZT-discontinued group, and in the 22 patients in the combination group, are summarized in Table 3. The age, sex distribution, and titer of H C V before t r e a t m e n t were not significantly different between the two groups. H C V was absent from the blood at the end of the treatment in 32.6% of the IFN-alone group and in 50.0% of the combination group, the difference between the groups not being significant. However, the H C V - n e g a t i v e rate at the end of A Z T administration (the end of the 15th week of treatment) in the combination group was 59.1%, significantly different (P < 0.05) from that in the IFN-alone group at the end of treatment. In patients with H C V - K 1 , at the end of treatment, 14.2% in the IFN-alone group and 45.5% in the combination group were HCV-negative, the rate of H C V negativity in the combination group being 3.2 times higher than that in the IFN-alone
Table 2. Adverse side effects of AZT Side effects
Number of patients
Anorexia Mild to moderate Severe a Nausea a Vomiting a General malaise Abdominal pain Abdominal fullness" Itching Diarrhea Anemia a Leuko-throbocytopenia~ Loss of hair
7 (23.3%) 6 (20.0%) 1 (3.3%) 5 (16.7%) 3 (10.0%) 2 (6.7%) 2 (6.7%) 1 (3.3%) 2 (6.7%) 1 (3.3%) 3 (10.0%) 1 (3.3%) 1 (3.3%)
aAZT administration was discontinued in eight patients. This was due to severe anorexia and vomiting in two patients; nausea and abdominal fullness in one patient; nausea and anemia in two patients; nausea, anemia (less than 300 x 104/mm3) and leukothrombocytopenia (less than 2000/mm3 WBC; less than 10 x 10a/ram3 platelets) in one patient; and vomiting in two patients
Table 3. Changes of HCV-RNA in the combination and IFN-alone groups Patients negative for HCV-5' NC Group
Type of HCV
No. of cases
Age (years)
M/F
K1 Other K2 PT UC
22 11 5 4 1 6
38.8 + 14.1 39.6 + 14.3 40.6 + 12.6 41.8 • 14.3 36 35.8 + 16.8
15/7 9/2 3/2 311 0/1 3/3
8.5 8.5 8.6 8.5
K1 Other K2 PT UC
43 28 10 9 1 5
45.6 47.4 45.8 46.2
25/18 16/12 7/3 7/2 0/1 2/3
8.3 8.2 8.3 8.6
Combination
IFN alone
+ 16.5 + 15.0 + 12.7 + 12.9 33 55.3 + 15.3
Titer HCV a + + + + 9 8.5 +
1.3 1.3 1.1 1.3 1.6
+ 1.5 + 1.6 _+ 1.4 + 1.5 7 9.1 + 1.4
*P < 0.05 vs IFN alone group; #P < 0.05; *#P < 0.01; #*#P < 0.001 vs K1 of IFN alone group UC, Unclassified, a 10n copies/ml
After AZT (15 weeks) 13" (59.1%) 6## (54.5%) 4 (80.0%)
3 1 3
(75.5~ (100%) (50.0%)
After INF (24 weeks) 11 5# 3
(50.0%) (45.5%) (60.0%)
2.
(50.0%)
1
(100%) (50.0%)
3 14 4 7 ###
6
(32.6%) (14.2%) (70.0%) (66.7%)
1
(100%)
3
(60.0%)
M. Tsutsumi et al.: Combination therapy with IFN and AZT
489
group. This difference was statistically significant (P < 0.05). At the end of AZT administration in patients with HCV-K1, the HCV-negative rate in the combination group was 54.5%, a highly significant difference (P < 0.01) from that in corresponding patients in the IFN-alone group at the end of treatment. In patients with other HCV genotypes, the HCV-negative rate was not significantly different between the IFN-alone and the combination groups (70.0% in the IFN-alone group and 60.0% in the combination group at the end of treatment, and 80.0% in the combination group at the end of AZT administration). In the unclassified cases, HCV was negative at the end of treatment in 50% of the combination group and in 60.0% of the IFN-alone group, these findings showing no significant difference. In the IFN-alone group, the HCV-negative rate was significantly lower in patients with HCV-K1 than in patients with other HCV genotypes. However, such a difference was not found in the combination group. The results of HCV-RNA examination in patients treated with 3 and 6 MU of IFN in the IFN-alone and combination groups are shown in Table 4. The rate of disappearance of HCV from the blood was slightly lower in the 6MU group than in the 3MU group in the IFN-alone group, and the rate was slightly higher in the combination group, except for those with HCVK1. In patients with HCV-K1 in the combination group, the disappearance rate was 57.1% in the 6MU group and 25% in the 3 MU group, that is, the value was twice as high in t h e 6 MU group. However, there were no significant differences between the 6-MU and 3-MU groups. The ALT responses in the IFN-alone and combination groups are shown in Table 5. The responses were not significantly different between the two groups, although the incidence of "good response" was clearly lower in patients with HCV-KI than in those with other HCV genotypes, including the unclassified cases, in both the IFN-alone and the combination groups.
Table 4. Rate of disappearance of HCV-RNA from the blood in patients treated with 3 or 6 MU of IFN Type of
Group
HCV
Combination K1 Others Total IFN alone
K1 Others Total
ALT Response
No. of patients
Good
Partial
Poor
K1 Others
22 11 11
15 (68.2%) 5 (45.4%) 10(90.9%)
3 (13.6%) 3 (27.3%) 0 (0.0%)
4 (18.2%) 3 (27.3%) 1 (9.1%)
K1 Others
43 28 15
22 (5t.2%~ 9 (32.1~ * 13 (86.7%)
13 (30.2%) 13 (46.4%) 0 (0.0%)
8 (~8.6%) 6 (21.4%) 2 (13.3%)
I F N alone
* P < 0.002 vs others Others, K2a, K2b, PT, and unclassified
Patients negative
for HCV-5' NC
3MU 6MU 3MU 6MU 3 MU 6MU
4 7 6 5 10 12
1 (25.0%) 4 (57.1%) 3 (50.0%) 3 (60:0%) 4 (40.0%) 7 (58.3%)
3MU 6MU 3 MU 6MU 3MU 6MU
12 16 7 8 19 24
2 (16.7%) 2 (12.5%) 5 (71.4%) 5 (62.5%) 7 (36.8%) 7 (29.2%)
Sequential changes in the titers of HCV, analyzed in 19 patients in the combination group, are shown in Figs. 2 and 3. In 2 patients in the K1 group and in 3 patients in the other genotype group, titers decreased rapidly during the initial 3 weeks of daily IFN administration. However, the decrease in titers slowed or titers increased again during the following 4 weeks of intermittent IFN administration. With the administration of AZT, titers again decreased clearly. After the completion of AZT administration, the titer increased again in 3 patients. In 4 patients in the K1 group and 2 patients of the other genotype group who were unclassified, the HCV-titers remained at high values throughout the treatment periods. In 1 patient in the K1 group (marked with an asterisk in Fig. 2), the titer decreased to 103 copies/ml during the initial 3 weeks, but increased again to 10 6 copies/ml in the following 4 weeks, remaining at a high value until the end of treatment, despite the administration of AZT. In 2 patients in the K1 group and 5 patients in the other genotype group, titers decreased to very low levels
Type of HCV
Combination
No. of
Others, K2a, K2b, PT, and unclassified
Table 5. Response of serum ALT level in the combination and IFN-alone groups
Group
Dose
of IFN patients
490
M. Tsutsumi et al.: Combination therapy with IFN and AZT
(10 | r
during the initial 3 or 7 weeks of treatment and remained at low levels until the end of treatment, except in 2 patients whose titer increased again after A Z T administration had ceased.
ml)
18 $ 7 6 $ 4
Discussion
3 2
,c2
8
.,rod
i
i
l's
I
AZT
z'4
I
Fig. 2. Sequential changes in blood hepatitis C virus (HCV) titer in patients with HCV-K1. In four patients, the hepatitis C virus (HCV) titer remained high throughout the period of treatment. In two patients, titers decreased rapidly during the initial 3 weeks, but the decrease slowed, or the titers increased again during the following 4 weeks. With the administration of AZT, the titers again decreased clearly. After AZT administration was stopped, the titer increased again in one patient. In one patient (asterisk), the titer decreased, to 103 copies/ml during the initial 3 weeks, but increased again, to 10 6 copies/ml, in the following 4 weeks, and it continued to remain at a high value until the end of treatment, despite the administration of AZT. Dots, HCVRNA positive; open circles HCV-RNA-regative
(11 n copies/ ml)
10 7
6 ,;
4
3
', \ ,
iz
,, '\
.f ">/
.
/
.
.
.
"'-..'g.
./ .-"
z
7
]
15
~zr
1
24
(...k,,
Fig. 3. Sequential changes in blood HCV titer in patients in the "other" type group, including unclassified cases. The titers responded well to the treatment, except in two patients whose genotype was unclassified. In three patients, the titers decreased rapidly during the initial 3 weeks, but the decrease slowed, or the titers increased again during the following 4 weeks. With the administration of AZT, the titers again decreased clearly. Continuous line, K2 type; dashed-zotted line, PT type; dashed line, unclassified. Dots and circles, as in Fig. 2 legend
A Z T inhibits viral RNA-dependent D N A polymerase (reverse transcriptase). Its antiviral selectivity is due to its greater affinity for reverse transcriptase than for human D N A polymerase. The antiviral activity is enhanced by IFN. 25 These characteristics of A Z T indicate that it may be an effective treatment for H C V infection. The study of Vento et al., 14 in which A Z T was administered to AIDS patients with H C V infection, strongly suggested the effectiveness of A Z T in H C V infection. In our previous preliminary study, ~s serum A L T activity and H C V titer in t h e blood were clearly decreased by the administration of A Z T for 4 - 8 weeks, and combination therapy with IFN and A Z T was effective in two patients. These results indicate that A Z T has an antiviral effect on HCV. In the present pilot study, the effects of a combination therapy with IFN and A Z T were analyzed and compared with the effects of treatment with IFN alone, although the number of patients examined is not sufficient to allow clear conclusions to be made. Although the H C V genotype is the most i m p o r t a n t determinant of the effects of IFN therapy, s-a~ the type and dose of IFN used and the titer of H C V before treatment may also influence IFN therapy. 4'7'a~ In the combination group in this study, only natural IFN alpha was used, whereas, on the other hand, various types of IFN were used in the IFN-alone group. However, the HCV-negative rates in the IFN-alone group at the end of treatment in the present study were similar to those reported in the study of Hagiwara et al., 4 in which study the treatment was performed in the same manner as in the present study, but only natural IFN alpha was used, indicating that the type of IFN has but small influence on its effectiveness. Since there are no conclusive findings in regard to differences in efficacy between 6 M U - and 3-MU IFN treatment, and since IFN is very expensive, in the present study, we administered either 6 MU or 3 MU of IFN depending on the selection of patient. The HCV-negative rate was similar in the 6- and 3-MU treated groups in both the combination and IFN-alone groups, except for the patients with HCV-K1 in the combination group. These results also suggest that the dose of IFN has but small influence on its effectiveness. In the present study, HCV-titers before treatment were not significantly different in the combination and IFNalone groups.
M. Tsutsumi et al.: Combination therapy with IFN and AZT There was no significant difference between the combination and IFN-alone groups in HCV-negative rates calculated in all patients at the end of treatment. However, the negative rate in patients with HCV-K1 was 3.2 times higher in the combination group than in the IFN-alone group, showing a statistically significant difference. On the other hand, there was no significant difference in HCV-negative rates between the IFNalone and combination groups in patients with other HCV genotypes. The HCV-negative rates in patients with different HCV genotypes in the IFN-alone group in the present study were very similar to those reported by Kanai et al. 9 Recently, Mita et al) ~ also reported similar results in a study in which patients were treated only with natural IFN alpha in the same manner as in the present study. In that study, the HCV-negative rate in patients with HCV-K1 was quite compatible with that found for the IFN-alone group in the present study (E. Mita, personal communication, 1994). These results indicate that the combined administration of AZT with IFN increases the HCV-negative rate evoked by IFN in patients with HCV-K1. Sequential changes in HCV-titers showed that the decrease in titer was accelerated by AZT in some patients. This effect of AZT may account for the better results of combination therapy with AZT and IFN. In the IFN-alone group, the HCV-negative rate in patients with HCV-K1 was significantly lower than that in patients with other HCV genotypes. However, no such difference was found in the combination group. The HCV-negative rate in the 3- and 6-MU groups differed only in patients with HCV-K1 in the combination group, and not in the other groups. These results suggest that the administration of AZT improves the effect of IFN only in patients with HCVK1, in whom the effect of treatment with IFN alone is poor. On the other hand, the effect of AZT administration in patients with other HCV genotypes is not clear, due to the better effect of IFN-alone treatment in this group. There was no difference in ALT response between the combination and IFN alone groups. The discrepancy between the HCV-negative rate and to ALT response may be due to the good ALT response in patients in whom the HCV-titer was decreased by the treatment, although HCV-5'NC was still positive a~ the end of the treatment. In these patients, serum ALT levels may rise again during the post-therapeutic period. In patients who were negative for HCV-RNA at the end of treatment, the ALT response was good and the improvement in the HA1 score was prominent, indicating that HCV-RNA disappeared from blood in parallel with the improvement of hepatitis. At the present time, the reason for the effect of IFN being poor in patients with HCV-K1 is obscure, al-
491 though the possibilities mentioned in the introduction can be considered. The sequential changes in HCVtiter show that all patients in the other genotype group, except for the unclassified cases, in which group patients with HCV-K1 may be included, responded to IFN administration. On the other hand, about half of the patients with HCV-K1 did not respond to IFN. In these patients, combination therapy with IFN and AZT cannot be expected to be effective. In the present study, to confirm the basal changes due to treatment with IFN alone, AZT administration was begun from the 8th week of IFN treatment. Effects of the combination administration of AZT were recognized only in patients whose HCV-titer was decreased to 103 copies/ml by IFN. The changes in a patient whose HCV-titer decreased to 103 copies/ml during the initial 3 weeks and then increased again to 106 copies/ml during the following 4 weeks suggest that the combined administration of AZT should be started from an earlier stage of IFN treatment, since AZT was without effect in this patient. A disadvantage of AZT treatment is the high incidence of side effects, and AZT administration had to be discontinued in 8 patients. After AZT administration was stopped, HCV-RNA was again positive in 3 patients in the combination group, and the HCV-titer increased in 5 patients. These results suggest that the administration of AZT may need to be continued for more than 8 weeks to improve the effects of the combination therapy. However, a longer duration of administration is very difficult, due to the increase in the severe side effects. The results of the present pilot study provide tantalizing evidence that combination therapy with IFN and AZT may be an effective treatment for chronic type C hepatitis caused by the K1 type. However, a doubleblind randomized controlled study on a larger number of patients, carried out with the same dose of IFN, is required to confirm whether this combination is effective, although there is a considerable possibility that long-term treatment with IFN alone may enhance the development of IFN-resistant strains of HCV, as shown by the results of the present study. Because of the side effects of AZT, its use has some limitations. The development of other anti-viral drugs that are effective against HCV infection but that have fewer side effects may be important for the further improvement of IFN therapy for type C hepatitis. Recently, the effectiveness of two antiviral drugs, ribavirin26'27 and ofloxacin,28 on HCV infection was reported. Comparative studies on the effects of AZT and ribavirin or ofloxacin on HCV may be needed in future.
Acknowledgments. This work supported, in part, by a Grantin-Aid for Scientific Research (C) (No. 05670502) from the Ministry of Education, Science, and Culture of Japan.
492
M. Tsutsumi et al.: Combination therapy with IFN and A Z T
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