The C-EDGE treatment-experienced study forms part of a suite of
studies in previously untreated people (treatment naive), people who have taken treatment before (treatment experienced) and people with HIV co-infection.
Results from the treatment-experienced arms of the C-EDGE
study were presented as a conference poster by Dr Paul Kwo of the University of
Indiana.
The study recruited participants with genotypes 1, 4 or 6
hepatitis C infection, including people with HIV and hepatitis C co-infection.
People were eligible to join the study if their hepatitis C had failed to respond to
previous treatment with pegylated interferon and ribavirin.
In this study, participants were randomised to one of four
arms:
- Grazoprevir & elbasvir once daily for 12
weeks.
- Grazoprevir & elbasvir once daily for 12
weeks, plus twice-daily weight-based ribavirin.
- Grazoprevir & elbasvir once daily for 16
weeks.
- Grazoprevir & elbasvir once daily for 16
weeks, plus twice-daily weight-based ribavirin.
Study arms were stratified by cirrhosis and prior treatment
response (null response, partial response or post-treatment relapse) in
order to ensure equal distribution of these factors across study arms.
In total, 420 participants were randomised (209 to the 12-week arms
and 211 to the 16-week arms), of which 58% in the 12-week arm had genotype 1a
infection and 11.5% had genotype 4 infection. The remainder in the 12-week arm
had genotype 1b infection.
In the 16-week arms, genotype 1a representation was slightly
lower in the ribavirin-free arm than in the ribavirin-containing arm (46% vs
55%), and the 16-week arms had a lower representation of participants with genotype 4 (6%).
Approximately 5% of
participants had HIV and hepatitis C co-infection. The distribution by
previous treatment history was 35% relapse, 22% partial response and 43% null
response. Seventy-three people had cirrhosis.
The primary efficacy results showed a high level of efficacy
in all study arms, with marginally greater efficacy in the 16 week plus
ribavirin arm. However, subgroup analyses which excluded patients counted as
non-virologic failures (e.g lost to follow up or protocol violation), found a
stronger tendency towards greater efficacy in those randomised to 16 weeks plus
ribavirin, except in prior relapsers.
|
|
Response by baseline
characteristics
|
Study arm
(grazoprevir & elbasvir)
|
SVR12 (all)
|
Cirrhosis
|
Prior relapse
|
Prior partial or null response
|
12 weeks
|
92%
|
89%
|
100%
|
91%
|
12 weeks + ribavirin
|
94%
|
88%
|
100%
|
91%
|
16 weeks
|
92%
|
92%
|
92%
|
94%
|
16 weeks + ribavirin
|
97%
|
100%
|
100%
|
100%
|
When responses were analysed by genotype in an
intent-to-treat analysis, genotype 1b participants showed better responses to
the 12-week ribavirin-sparing regimen when compared to genotype 1a but no other
substantive difference were evident. The small number of genotype 4 patients
(n = 37) and people with HIV co-infection (n = 21) do not permit comparisons between
regimens, except to note that people with HIV co-infection did not respond less
well.
|
Response by baseline
characteristics
|
Study arm
(grazoprevir & elbasvir)
|
Genotype 1a
|
Genotype 1b
|
Genotype 4
|
HIV co-infection
|
12 weeks
|
90%
|
100%
|
78%
|
100%
|
12 weeks + ribavirin
|
93%
|
96%
|
96%
|
100%
|
16 weeks
|
94%
|
96%
|
93%
|
83%
|
16 weeks + ribavirin
|
95%
|
100%
|
100%
|
100%
|
As in previously untreated patients, the presence of
resistance-associated variants (RAVs) conferring a greater than fivefold
reduction in sensitivity to elbasvir (NS5A inhibitor) was associated with a
substantially poorer SVR12 rate in 21 genotype 1a patients (52%, compared to
99% in patients without any RAVs). In comparison, variants associated with
reduced sensitivity to grazoprevir (NS3 protease inhibitor) did not affect
virological response.
Study medication was well tolerated. Approximately 3% of
participants in each study arm experienced a serious adverse event and a total of 7
participants (5 in the 16-week plus ribavirin arm) discontinued study
medication due to adverse events. In the ribavirin-containing arms, 8% of the
12-week and 20% of the 16-week group developed haemoglobin below 10 g/dL.
These findings indicate that for people with genotype 1b and for people with
a history of prior relapse after treatment response, a 12-week course of
treatment without ribavirin is highly effective, curing 100% of those patient
groups in this study. But for people with cirrhosis and for prior partial or null
responders, a 16-week course of treatment with ribavirin may be necessary to
achieve a 100% cure rate, the investigators concluded.