The next-generation hepatitis C protease inhibitor
simeprevir cured almost 80% of previously untreated people with hepatitis C and
HIV co-infection when used in combination with pegylated interferon and
ribavirin, Prof. Doug Dieterich of Mount Sinai Medical Center, New York,
reported last week at the 21st Conference on Retroviruses and Opportunistic
Infections (CROI) in Boston.
received marketing approval for treatment of hepatitis C mono-infection in the US
November 2013 and is currently awaiting approval in the European Union.
Simeprevir is a second-generation HCV protease inhibitor that is better
tolerated than telaprevir and boceprevir, the first protease inhibitors
approved for hepatitis C treatment. It is dosed once daily in combination with
pegylated interferon and ribavirin. It is currently licensed for treatment of
genotype 1 infection, but is active against all genotypes with the exception of
Product developer Janssen designed the phase III C212 study
in order to establish the efficacy of simeprevir in people with HIV and
hepatitis C co-infection. The study recruited 106 people with
genotype 1a (n=88) or 1b (n=18) infection, without liver cirrhosis, stratified according to previous
treatment history. Half of participants (53) had not previously taken hepatitis C treatment. The
remainder were relapsers (15), partial responders (10) and null responders
(28). Null responders are least likely to respond to a subsequent
interferon-based regimen because, by definition, they did not respond to a
previous interferon-based regimen and are therefore likely to have poor ability
to either tolerate or respond to subsequent interferon treatment.
An inherited gene which all individuals have. There are three genotypes of IL28B; these influence response to hepatitis C and its treatment. People with CC genotype are more likely to spontaneously clear acute infection or (during chronic infection) respond well to interferon-based treatment. The other two genotypes are known as CT and TT.
A shortage of neutrophils, a type of white blood
cell that fights bacterial infections.
The trial evaluated a once-daily dose of simeprevir in
combination with pegylated interferon and ribavirin according to a
response-guided treatment protocol. Previously untreated participants and prior
relapsers received 12 weeks of treatment with simeprevir and 24 or 48 weeks of treatment
with pegylated interferon and ribavirin, according to virologic response at
weeks 4 and 12. Partial or null responders all received 48 weeks of interferon
treatment, as did people with cirrhosis.
The study population was 85% male and 14% African-American
with an average age of 48 years. 82% of participants had genotype 1a infection.
Eighty-eight per cent of study participants were taking antiretroviral therapy
during the study. The baseline CD4 count of participants was high: 561 cells/mm3
in those taking antiretroviral therapy (ART) and 677 cells/mm3 in those not taking ART.
The primary endpoint of the study was the proportion of participants
with a sustained virological response 12 weeks after completing
treatment (SVR12) compared to a historical control derived from the
study of pegylated interferon and ribavirin treatment in people with HIV
and HCV co-infection.
74% of all study participants achieved SVR12. Among participants who had
not previously taken hepatitis C treatment, 79% achieved SVR12 (42 of
53 participants), compared to 29% treated with
pegylated interferon and ribavirin in the historical control group
The total number of relapsers, partial responders and null
responders was too small to allow statistical comparison between arms. 87% of
relapsers, 70% of partial responders and 57% of null responders achieved SVR12.
In comparison 5% of null responders in the historical control group achieved
Eighty-nine per cent of participants met the criteria for
response-guided therapy and achieved SVR12 after a 24-week treatment course and
there was no difference between previously untreated patients and prior
relapsers in this respect.
A number of sub-group analyses were carried out in order to
tease out where differences might exist in responses to treatment. In
particular, the investigators looked at differences between genotypes 1a and 1b,
and between patients with and without the Q80K hepatitis C mutation. This
naturally-occurring mutation, or polymorphism, is present in approximately half
of all cases of genotype 1a infection, but is not present in genotype 1b virus.
Eighty-nine per cent of all patients with genotype 1b
infection achieved SVR12 compared to 71% of patients with genotype 1a. No difference
was found in treatment response in genotype 1a patients according to the
presence of the Q80K mutation (67% with vs 72% without). This lack of
difference, suggested Prof. Dieterich, may be a consequence of higher adherence
among people living with HIV, which may be enough to overcome the presence of
The investigators also analysed responses according to the
degree of liver damage, although the proportion of participants with advanced liver
damage (fibrosis stages F3 and F4) was relatively low, at 21%. In previously untreated patients,
89% of those with less advanced liver disease (F0-F2) achieved SVR12 compared
to 57% of those with F3/F4 disease. In other study arms, the numbers treated are
too small for meaningful comparison. Overall, 80% of F0-F2 patients and 64% of
F3-F4 patients achieved SVR12.
Treatment with simeprevir and pegylated interferon/ribavirin
was fairly well tolerated. Four patients discontinued treatment due to
events and throughout the entire study 46 patients experienced grade 3
adverse events, of which ten were categorised as serious. Grade 3 and 4
events were largely attributable to pegylated interferon and ribavirin
(neutropenia, pruritus). Rash occurred in 16 participants during the
first 12 weeks
of treatment, but none were serious cases. There were two cases of grade
3 or 4
photosensitivity, both known side-effects of simeprevir. The most
frequent side-effects (each experienced by at least 25% of patients)
were headache, rash and
Grade 3 or 4 haemoglobin reductions or bilirubin elevations
were rare, occurring in only 1.3% of patients.
Participants with the IL28B 'CC' genotype, which confers a
better response to interferon-based treatment, were more likely to achieve
SVR12 (96 vs 68 and 61% of 'CT' and 'TT' genotypes respectively). All previously untreated
patients, prior relapsers and partial responders with the 'CC' genotype achieved
SVR12, as did 88% of previous null responders, suggesting that IL28B genotype will continue to be an important
consideration when determining whether to embark on a course of treatment with
simeprevir. A similar difference was apparent in the faldaprevir study also
presented during the conference session. Professor Jurgen Rockstroh, session
chair, questioned whether triple regimens combining a protease inhibitor with
pegylated interferon and ribavirin are sufficiently potent to cure patients
with a non-CC IL28B genotype, whether or not they have HIV co-infection.