High-dose interferon α-2a with ribavirin and amantadine in naïve chronic hepatitis C patients — results of a randomized, prospective, pilot study
Correspondence to: Dr H. Ullerich, Department of Medicine B, Westfaelische Wilhelms-Universitaet Muenster, Albert-Schweitzer-Str. 33, D-48 129 Muenster, Germany. E-mail: firstname.lastname@example.org
Background : Hepatitis C viral kinetic studies have demonstrated the increased anti-viral effect of higher than standard dosages of interferon and of daily treatment schedules.
Aim : To compare, in a prospective, randomized, controlled trial, the efficacy and safety of high-dose interferon-α therapy vs. standard-dosage interferon-α therapy, in a triple therapy combination with ribavirin and amantadine.
Methods : Previously untreated patients with chronic hepatitis C were randomized to the standard interferon-α group (n = 15), receiving thrice weekly 6 MU interferon-α for 12 weeks, followed by 3 MU interferon-α for 36 weeks, or the high-dose interferon-α group (n = 15), receiving daily 9 MU interferon-α for 4 weeks, followed by 6 MU (weeks 5–8), 3 MU (weeks 9–12) and 1.5 MU (weeks 13–48) interferon-α. All patients were given ribavirin (1000–1200 mg) and amantadine (200 mg) daily for 48 weeks.
Results : At the end of treatment and after the 24-week follow-up period, serum hepatitis C virus RNA was undetectable in eight (53%) and six (40%) patients treated with standard-dosage interferon-α, respectively, compared with 11 (73%) and 10 (67%) treated with high-dose interferon-α, respectively (not significant). The safety profile of both treatment regimens was similar. Severe adverse events leading to withdrawal from the study occurred in one patient (7%) in each group, and in both groups one patient (7%) was lost during therapy for unknown reasons.
Conclusions : The findings suggest that, although the difference between the response rates of standard and high-dose interferon-α regimens (within a triple anti-viral therapy combination) did not reach statistical significance, there was a clear trend towards a higher response with high-dose interferon-α therapy and an equal safety profile.
Interferon-α (IFN-α) is an essential component of therapy for patients with chronic hepatitis C virus (HCV) infection, and can achieve viral clearance and improve both the histology and prognosis.1 Recently, the addition of ribavirin to the standard IFN-α regimen has resulted in impressively improved sustained virological responses in naive patients with chronic hepatitis C.2, 3 However, about 60% of these patients do not achieve a sustained virological response, clearly documenting the need for a more effective therapeutic alternative.
Therapy with other anti-viral agents, such as amantadine, is experimental. Nevertheless, previous pilot studies have revealed some promising results in patients treated with amantadine alone,4, 5 amantadine in combination with IFN-α5, 6 or as triple therapy combining IFN-α, ribavirin and amantadine.7 Another approach to improve the therapeutic efficacy involves modifications of the IFN-α dose and dosing regimen, as the optimal dose and duration of IFN-α therapy remain poorly defined.8, 9 The three times weekly application regimen of standard IFN-α therapy is not based on pharmacogenetic or pharmacological principles, nor on the viral kinetics of HCV: IFN-α has a half-life of approximately 8 h10 and, although the calculated half-life of HCV in serum is limited (6–7 h), the estimated rate of HCV replication within the intracellular reservoir is extremely high (approximately 3.7 × 1011 virions/day).11 Moreover, viral kinetic studies of HCV-infected patients during IFN-α therapy have demonstrated the increased anti-viral effect of higher than standard dosages of IFN-α and of daily vs. thrice weekly treatment schedules.11–15 These findings indicate that the currently recommended standard IFN-α regimen does not allow adequate serum concentrations to be maintained to suppress HCV replication effectively and, consequently, may be responsible for the poor response observed following treatment. Accordingly, high-dose IFN-α induction therapy with daily dosing may lead to a more rapid depletion of the intracellular HCV reservoir and to an increase in the long-term sustained response, as recent studies have proposed.16–19
The aims of this prospective, randomized, controlled, pilot study were to compare the efficacy and safety of high-dose IFN-α induction therapy plus ribavirin plus amantadine vs. standard IFN-α therapy plus ribavirin plus amantadine in naive patients with chronic hepatitis C.
Thirty consecutive patients with chronic hepatitis C, not previously treated, were enrolled in the study. Eligible patients tested positive for anti-HCV (second-generation enzyme immune assay) and HCV RNA (reverse transcription-polymerase chain reaction), had a liver biopsy sample taken within 12 months of study entry confirming chronic hepatitis, and showed elevated serum alanine aminotransferase concentrations (at least1.5-fold) for at least 6 months before the start of the protocol. Entry haemoglobin had to be at least 13 g/dL in males and 12 g/dL in females, the leucocyte counts at least 2500/µL and the platelet counts greater than 70 000/µL. Standard exclusion criteria were applied with regard to contraindications to IFN, ribavirin and amantadine, immune suppression, concomitant other causes of liver disease, evidence of decompensated liver disease, other severe diseases, and intravenous drug use and alcohol abuse within the previous year.
This study was a randomized, prospective trial conducted at the University Hospital of Muenster, Germany. It received local ethics committee approval according to the Declaration of Helsinki, and all patients gave signed informed consent. Enrolment of patients began in December 1998, and the trial was completed in March 2001.
All patients received triple therapy consisting of IFN-α-2a (RoferonA, Hoffmann-La Roche AG, Grenzach-Wyhlen, Germany), ribavirin (Medunapharm, Hannover, Germany) and amantadine sulphate (Infex, Merz + Co. GmbH Co, Frankfurt a.M., Germany) for 48 weeks. The patients were randomly assigned to one of the two treatment groups, either standard IFN-α therapy or high-dose IFN-α induction therapy. The randomization ratio was 1 : 1. Patients assigned to standard IFN-α therapy received 6 MU IFN-α subcutaneously three times per week for 12 weeks, followed by 3 MU IFN-α three times per week for 36 weeks. Compared to the conventional definition of standard-dose IFN (3 MU thrice weekly), the ‘standard’ IFN regimen used within this study is modified. As former studies have suggested a higher response to a regimen with an initially higher dose of IFN (6 MU IFN thrice weekly for weeks 1–12, so-called induction arm), we have used this regimen as our ‘standard’ for years. Accordingly we refer to this regimen as ‘standard’, although this is not entirely in keeping with the widely accepted definition of standard IFN.
Patients assigned to high-dose IFN induction therapy received 9 MU IFN-α daily for 4 weeks, followed by 6 MU (weeks 5–8), 3 MU (weeks 9–12) and 1.5 MU (weeks 13–48) IFN-α daily. All patients were given ribavirin, 1000 mg (weight, ≤75 kg) or 1200 mg (weight, > 75 kg), and 200 mg amantadine sulphate twice daily orally in divided doses for 48 weeks.
After the initial 24-week course of treatment, patients were evaluated for virological response. Only in patients who had achieved a virological response (HCV RNA undetectable) at week 24 was therapy continued. After the end of treatment, all patients were followed up for 24 weeks.
All patients were evaluated as out-patients for safety and efficacy at the end of weeks 1, 4, 8, 12, 18, 24, 36, 48, 60 and 72. Biochemical and haematological testing was performed in a local laboratory at each visit. Serum HCV RNA was quantified by a standardized reverse transcription-polymerase chain reaction assay (Amplicor Monitor HCVTM version 2.0, Roche Diagnostic Systems, Branchburg, NJ, USA) at baseline and at each visit. HCV genotyping was performed by reverse hybridization assay (Inno-LiPA HCV II, Innogenetics N.V., Gent, Belgium).
The degree of hepatic inflammation and fibrosis was graded with a modified Knodell Histological Activity Index.20 The inflammation score was obtained by combining the scores for the first three components of this index: portal, periportal and lobular inflammation. The scores were in the range 0–18, with higher scores indicating more severe abnormalities. The degree of fibrosis was graded using a scale of 0–4 (0, absent; 1, mild without septa; 2, moderate with few septa; 3, numerous septa without cirrhosis; 4, cirrhosis).
The primary efficacy end-point was a sustained virological response, defined as undetectable serum HCV RNA levels 24 weeks after treatment was completed. Secondary end-points included the initial response and the end-of-treatment response, defined as undetectable serum HCV RNA levels at 24 and 48 weeks of therapy, as well as the biochemical response, defined as the normalization of the serum alanine aminotransferase concentration at weeks 24 and 48 of therapy and week 24 of follow-up. Further secondary end-points were the rate of dose reductions due to adverse effects or laboratory findings, the rate of adverse events leading to withdrawal from the study, and the rate of lost patients during therapy for other reasons.
Intention-to-treat analysis was used. All results are presented on the basis of the 30 patients who received at least one dose of study medication. Patients who discontinued treatment or were lost during follow-up were considered as virological non-responders. Descriptive statistics were calculated and reported as the mean ± standard deviation.
Between December 1998 and September 1999, 30 patients were randomized (Figure 1). Analysis is based on the data of the 15 patients assigned to standard IFN-α therapy plus ribavirin plus amantadine (IFN-SD) and the 15 patients assigned to high-dose IFN-α induction plus ribavirin plus amantadine (IFN-HD). The pre-treatment patient characteristics are shown in Table 1. As documented, both groups were balanced with respect to baseline characteristics. Patients in the IFN-HD group demonstrated slightly higher activities of mean alanine aminotransferase, aspartate transaminase and γ-glutamyltransferase. Most patients of both groups were infected with HCV genotype 1, with the IFN-HD group demonstrating the highest proportion. Histologically, the IFN-HD group showed a somewhat higher degree of acute inflammation and a slightly higher fibrosis stage.
Table 1. Demographic, biochemical, molecular and histological profile of patients with chronic hepatitis C at baseline
| No. (male/female)||15 (8/7)||15 (9/6)|
| Age (years) (mean ± s.d.)||41.4 ± 8.7||47.8 ± 15.5|
| Body weight (kg) (mean ± s.d.)||73.8 ± 11.2||73.1 ± 10.9|
| Years of infection (mean ± s.d.)*||15.2 ± 6.8||18.0 ± 13.2|
| Risk factor for infection|
| Transfusion|| 4/15 (26.7%)|| 5/15 (33.3%)|
| Parenteral drug use|| 1/15 (6.7%)|| 1/15 (6.7%)|
| Sporadic, other or unknown||10/15 (66.6%)|| 9/15 (60.0%)|
| ALT (U/L) (± s.d.)||48.6 ± 21.9||73.3 ± 55.1|
| AST (U/L) (± s.d.)||26.6 ± 10.4||38.1 ± 26.5|
| γ-GT (U/L) (± s.d.)||41.6 ± 37.7||60.2 ± 74.7|
| Bilirubin (mg/dL) (± s.d.)|| 0.8 ± 0.8|| 0.6 ± 0.2|
| HCV genotype†|
| 1||10/14 (71.4%)||12/15 (80.0%)|
| 2 or 3|| 2/14 (14.3%)|| 3/15 (20.0%)|
| 4|| 2/14 (14.3%)|| 0/15 (0.0%)|
| HCV RNA > 1 × 106 copies/mL|| 8/15 (53.3%)|| 7/15 (46.7%)|
| HAI score (mean ± s.d.)‡|| 3.5 ± 1.8|| 4.0 ± 1.9|
| Fibrosis stage|
| None, mild or moderate||14/15 (93.3%)||12/15 (80.0%)|
| Severe|| 1/15 (6.7%)|| 3/15 (20.0%)|
Twenty-seven of the 30 randomized patients completed week 24 of therapy. One patient (week 8) in the IFN-SD group and two patients (weeks 1 and 8) in the IFN-HD group discontinued therapy. A virological response, with serum HCV RNA undetectable at week 4 of therapy, was seen in eight (53%) and 11 (73%) patients treated with IFN-SD and IFN-HD, respectively. At week 24, the respective virological response rates were 10 (67%) and 13 (87%). Treatment of patients with detectable HCV RNA at week 24 was discontinued (Figure 1). The treatment of one patient in the IFN-SD group was discontinued at week 36 due to an adverse event. Twenty-two patients completed 48 weeks of treatment. At the end of treatment, HCV RNA was undetectable in eight (53%) and 11 (73%) patients treated with IFN-SD and IFN-HD, respectively. During the 24 weeks of follow-up, virological relapse (positive HCV RNA in patients negative for HCV RNA at the end of treatment) occurred in two of the eight (25%) patients in the IFN-SD group and in one of the 11 (9%) patients in the IFN-HD group. The primary end-point, a sustained virological response at the end of the 24-week follow-up period, was observed in six (40%) patients on IFN-SD and in 10 (67%) patients on IFN-HD.
All patients with a virological response achieved this within the first 12 weeks of therapy; no later viral clearance was observed. Interestingly, all patients in both therapy groups who achieved a sustained virological response demonstrated an early negative HCV RNA polymerase chain reaction at week 4. The achievement of a virological response at week 4 was associated with a sustained response in 67% in the IFN-SD group and in 100% in the IFN-HD group. The virological and biochemical response rates are summarized in Table 2.
Table 2. Virological and biochemical responses during treatment, at the end of treatment (week 48) and at the end of the follow-up period (week 24 after the end of treatment)
| Week 4||8/15 (53.3%)||11/15 (73.3%)|
| Week 12||10/15 (66.7%)||14/15 (93.3%)|
| Week 24||10/15 (66.7%)||13/15 (86.7%)|
| End of treatment (week 48)||8/15 (53.3%)||11/15 (73.3%)|
| End of follow-up (week 72)||6/15 (40.0%)||10/15 (66.7%)|
| Week 12||9/15 (60.0%)||8/15 (53.3%)|
| Week 24||9/15 (60.0%)||9/15 (60.0%)|
| End of treatment (week 48)||7/15 (46.7%)||9/15 (60.0%)|
| End of follow-up (week 72)||5/15 (33.3%)||9/15 (60.0%)|
A variety of virus- and host-related variables that have recently been shown to predict virological response are given in Table 3.9 In the group of patients treated with IFN-SD, three of the 12 patients (25%) infected with HCV-1 or HCV-4 and both patients (100%) infected with HCV-2 or HCV-3 achieved a sustained response. Interestingly, in the IFN-HD group, a similar rate of sustained virological response (67%) was observed for patients infected with HCV-1 or HCV-4 and HCV-2 or HCV-3 (eight of 12 patients and two of three patients), respectively.
Table 3. Sustained virological response to different regimens according to baseline characteristics
| HCV 1 or 4||11/24 (45.8%)||3/12 (25.0%)||8/12 (66.7%)|
| HCV 2 or 3|| 4/5 (80%)||2/2 (100%)||2/3 (66.7%)|
|Mean HCV RNA|
| ≤ 1 × 106 copies/mL|| 8/15 (53.3%)||3/7 (42.9%)||5/8 (62.5%)|
| > 1 × 106 copies/mL|| 8/15 (53.3%)||3/8 (37.5%)||5/7 (71.4%)|
| ≤ 40 years|| 8/13 (62.4%)||3/7 (42.9%)||5/6 (83.3%)|
| > 40 years|| 8/17 (47.1%)||3/8 (37.5%)||5/9 (55.6%)|
| Male|| 8/17 (47.1%)||3/8 (37.5%)||5/9 (55.6%)|
| Female|| 8/13 (61.5%)||3/7 (42.9%)||5/6 (83.3%)|
| None, mild, moderate||15/26 (57.7%)||6/14 (42.9%)||9/12 (75.0%)|
| Severe|| 1/4 (25.0%)||0/1 (0.0%)||1/3 (33.3%)|
The rate of sustained biochemical response was higher amongst patients who received IFN-HD (60%) than amongst those who received IFN-SD (33.3%) (Table 2). The combined rate of sustained biochemical and virological responses in the IFN-HD group was 60% (nine of 15 patients), compared with 33.3% (five of 15 patients) in the IFN-SD group. The normalization of serum alanine aminotransferase values was associated with undetectable levels of serum HCV RNA in all patients who showed a sustained virological response. In one of five patients (20%) in the IFN-SD group and one of nine patients (11%) in the IFN-HD group, who showed a sustained virological response, no biochemical response was documented. Both patients showed severe fibrosis at baseline histology, pointing to a delayed biochemical response due to baseline histology.
Interestingly, a poor correlation between biochemical and virological responses at weeks 12 and 24 was observed within the IFN-HD group (53.3% and 60% for biochemical response vs. 93.3% and 86.7% for virological response, respectively), whereas a clear correlation was documented in the IFN-SD group. This may partly be attributed to the higher number of patients with severe fibrosis at baseline histology within the IFN-HD group (20% in the IFN-HD group vs. 6.7% in the IFN-SD group), necessitating a longer period of time for normalization of transaminases despite an already positive virological response.
At baseline, the mean haemoglobin values were all within the normal range in patients treated with IFN-SD and IFN-HD (14.8 ± 1.2 g/dL and 15.1 ± 1.1 g/dL, respectively), and most of these decreased within the first 12 weeks of therapy in both regimens (12.8 ± 1.1 g/dL in the IFN-SD group and 12.4 ± 0.8 g/dL in the IFN-HD group), with a slightly more pronounced decrease in the IFN-HD group.
A decrease was observed in the mean leucocyte count, with a maximum decrease at week 12 of therapy, which was more pronounced in the IFN-HD group. Leucocytes decreased from 6.4 ± 1.4/µL (baseline) to 3.8 ± 1.3/µL (week 12) in the IFN-SD group and from 6.1 ± 1.4/µL (baseline) to 3.3 ± 0.8/µL (week 12) in the IFN-HD group.
The median platelet count decreased, reaching a plateau by week 12, with the decrease being slightly larger in the IFN-HD group [189 ± 54/µL (baseline) to 152 ± 44/µL (week 12)] compared to the IFN-SD group [214 ± 55/µL (baseline) to 189 ± 66/µL (week 12)]. The median platelet count returned to baseline values by week 48 in both groups.
Symptoms such as flu-like syndrome and fatigue during therapy were commonly observed regardless of the study treatment group. The frequency and type of other untoward symptoms were similar to those commonly reported in patients treated with IFN plus ribavirin,9, 10 and showed no predominance in either group. Dose reduction due to symptoms related to therapy or severe abnormal laboratory findings was not necessary in either group. In both groups, one patient was withdrawn prematurely from the study due to adverse events: one patient in the IFN-HD group (week 2) suffered from severe diarrhoea and severe flu-like symptoms, and one patient in the IFN-SD group showed a transient ischaemic attack-like episode with transitory aphasia (week 36). In both groups, one patient was lost during therapy for unknown reasons.
The observations made in this pilot study demonstrate the potential benefit of the high-dose IFN-α induction regimen compared with standard IFN-α therapy when given in combination with ribavirin and amantadine. Although this study only consisted of a relatively small number of patients, and therefore the differences did not reach statistical significance, there was a clear trend towards a higher response with IFN-HD therapy compared with IFN-SD therapy in the treatment of naive patients with chronic hepatitis C. IFN-HD was associated with the highest sustained virological and biochemical responses (67% and 60%, respectively). The overall responses were higher than those observed with IFN-SD (40% and 33% for virological and biochemical responses, respectively). However, the efficacy of IFN-SD in this study was comparable in terms of all study end-points with previously reported results of standard IFN-α plus ribavirin therapies.2, 3 The higher rates of sustained virological response with the IFN-HD regimen were the result of higher rates of initial response (87% vs. 67% for IFN-HD and IFN-SD, respectively) and end-of-treatment response (73% vs. 53%), and the lower rates of relapse in the follow-up period (9% vs. 25%). Although the stopping of treatment in patients not achieving a virological response by week 24 may have biased the results towards a favourable response to the high-dose induction regimen, this is considered to be unlikely, as late virological responses are seen in only a minority of patients. The determination of whether the additional administration of amantadine provides further beneficial effects, as reported previously,5, 7 was beyond the scope of this study, as both study arms used the same dose and application regimen of amantadine. However, amantadine may contribute to a reduction in IFN-α-related adverse effects in combination therapy, as recent studies have suggested.21
Concordant with previous studies,2, 3, 22 patients allocated to the IFN-SD regimen and infected with unfavourable HCV genotypes 1 and 4 had a significantly lower rate of sustained response compared to patients infected with HCV genotypes 2 and 3 (25% and 100%, respectively). Interestingly, in patients allocated to the IFN-HD regimen, genotype was not a predictor of response, as in all study end-points similar rates of response were observed in patients infected with genotypes 1 and 4 when compared with patients infected with genotypes 2 and 3. Viral characteristics (high viral load and genotype 1) are considered to be key factors in the lack of response,2, 23 and explanations have been sought by suggesting special viral properties.24 In a recent viral kinetic study, difficult to treat patients were treated with a high initial IFN dose, and high rates of viral suppression were achieved in the large majority of patients.19 These results suggest that the concept of IFN resistance is related more to dose than to the intrinsic characteristic of the virus. Therefore, these data point to the potential usefulness of high-dose induction IFN therapy in difficult to treat patients, such as those with HCV genotypes 1 and 4.
The improvement demonstrated in response to IFN-HD therapy is impressive, with the sustained virological response rate being 1.7-fold higher with the IFN-HD regimen than with the IFN-SD regimen. The improvement in virological response seems to be directly attributable to the daily high-dose IFN-α regimen, as the baseline characteristics of the patients were comparable in both groups. In IFN-α monotherapy settings, some recent studies have utilized higher doses and/or higher application frequencies of IFN-α for initial treatment, as well as for re-treatment, of chronic HCV infection.17, 18, 25–27 So far, the potential effect of high-dose IFN-α induction has not been well characterized, as many of these studies did not compare directly the high-dose regimen with standard-dose IFN-α therapy. It is also important to note that many of these studies, particularly those published prior to 1997, employed biochemical criteria to define treatment response. Despite these limitations, most studies observed that the increase in viral clearance and improved response at the end of treatment were dependent on the IFN-α dose. In contrast, the long-term benefits of increasing the dose or dosing frequency of IFN-α alone have been disappointing. When therapy was discontinued or the IFN-α dose was reduced, a high rate of relapse or breakthrough was observed. As a result, the use of high-dose IFN-α regimens is not associated with a significant increase in long-term sustained virological response when compared with standard-dose treatment.28
The recently demonstrated significant increase in the long-term virological sustained response with initial treatment with standard IFN-α and ribavirin seems to be primarily attributable to a reduction of the relapse rate following the end of therapy and, to a lesser extent, to an increase in the initial response.2, 3 In conclusion, combining a high-dose IFN induction regimen to induce higher rates of initial response, as pointed out above, and ribavirin co-therapy, in order to decrease breakthrough and relapse rates, should bring about an increase in the overall sustained response. Although randomized studies tackling these aspects have not been performed, our data indicate the potential efficacy of such a regimen.
However, patient tolerance to high-dose IFN is of concern, as many of the problematic side-effects of IFN are dependent on dose.29 The safety profile of the patients in both groups in this study reflected the known side-effects of each drug given as monotherapy and was consistent with that reported in previous studies.2, 3, 7 Surprisingly, the incidence of the adverse effects in the IFN-HD group was similar to that in the IFN-SD group. The rate of discontinuation of therapy for adverse effects or dropouts for other reasons was low, was observed with the same frequency in both groups (13%), and was comparable with previous reports on standard combination therapy.2, 3, 7 The changes in several haematological parameters were related to dose, but the effects were generally mild and transient, and treatment withdrawal or dose reduction due to pathological laboratory findings was not required in any patient.
In future, the potential benefit of high-dose IFN induction triple therapy, as demonstrated here, will need to be compared with pegylated IFN-α, which has shown promising results in recent trials.30–32 Whether comparable results concerning the sustained virological response will be achievable with pegylated IFN-α cannot be judged at present due to a lack of data on combination therapy with pegylated IFN-α and ribavirin. Whether pegylated IFN-α can match the viral kinetics and initial high viral burden better than high-dose IFN-α induction therapy, which allows sudden large increases of serum IFN-α in short repetitive cycles, needs to be investigated.
Based on the results of this randomized, prospective, pilot trial, high-dose IFN induction therapy appears to offer superior efficacy and a similar safety profile compared to the standard-dose IFN protocol. However, the number of patients enrolled and evaluated in the present study was relatively small. Nevertheless, the positive results presented here warrant confirmation in larger trials.