A 12-week course of three direct-acting antivirals developed by AbbVie,
plus ribavirin, cured 96.3% of treatment-experienced patients with hepatitis C
genotype 1 infection, Professor Stefan Zeuzem of the JW
Goethe University Hospital, Frankfurt, Germany told the 49th Annual Meeting of the European Association for the Study of the Liver in London
on Thursday.
The AbbVie combination consists of three drugs which each target a different
stage in the viral lifecycle of hepatitis C virus (HCV), used without interferon. New
interferon-free combinations are being developed by several pharmaceutical
companies, and represent a major advance on the previous standard of care.
Interferon-free treatment appears better tolerated, and can cure a much higher
proportion of patients in a shorter time.
The data presented by Prof. Zeuzem come from the SAPPHIRE II study, a
phase III study which recruited 394 people with genotype 1 hepatitis C (58% genotype
1a, 41% genotype 1b) who did not respond to a previous course of dual HCV
therapy with pegylated interferon/ribavirin. Patients were eligible for
inclusion if they had relapsed, had a partial response or had a null response.
In the study, 49% of participants were previous null responders. The study was designed
to evaluate a 12-week course of interferon-free treatment in a patient
population that has been hard to treat with interferon-based therapy.
Glossary
- erythropoietin
-
A natural hormone made in the kidneys to stimulate the production of red blood cells by the bone marrow.
The median age of study participants was 55 years. The study population
had less advanced liver disease. None of the study participants had cirrhosis, and 68%
had F0 or F1 fibrosis.
Participants were randomised on a 3:1 basis to receive the oral interferon-free
combination or placebo.
The investigational therapy consisted of the protease inhibitor ABT450
with ritonavir booster (150mg/100mg once daily), the NS5A inhibitor ombitasvir (ABT-267)
(250mg once daily) and the non-nucleoside NS5B polymerase inhibitor dasabuvir (ABT-333) (250mg twice
daily) and ribavirin.
Therapy lasted for twelve weeks and the primary outcome was the
sustained virological response rate twelve weeks after the completion of
treatment (SVR12).
Overall, 96.3% of patients receiving the investigational therapy had SVR at week twelve (95% confidence interval 94.2-98.4%). SVR12 rates were
similar according to previous treatment outcome (95.3% for individuals who
relapsed, 100% for patients with a partial response and 95.2% for those who had
a prior null response).
SVR12 rates among people receiving the study medication were
comparable for genotype1a and genotype 1b (96 vs 96.7%). All cases of
virologic failure in the study occurred after the completion of treatment:
seven patients experienced a viral breakthrough between two and eight weeks
after completing treatment. Six of these viral breakthroughs occurred in
patients who had been null responders to previous treatment.
The only adverse event that occurred more frequently in the investigational
therapy arm was pruritus (itching), which was reported by 13.8% of patients in the
treatment arm and 5.2% of those receiving the placebo (p<0.05). Only 1% of
patients receiving the investigational combination discontinued therapy early.
These three discontinutions were due to elevated liver enzymes (ALT/AST),
severe diarrhoea and renal failure that occurred on the first day of treatment.
This case was considered unconnected to the investigational therapy.
There was no significant difference in the development of laboratory
abnormalities. Less than 5% of patients developed anaemia as a consequence of
ribavirin treatment, and no patient developed anaemia that was severe enough to
require erythropoietin treatment in order to restore haemoglobin to normal
levels.
Questioned regarding the extent to which patients were excluded from the
study due to potentially hazardous drug-drug interactions caused by ritonavir
(an inhibitor of CYP3A4, a liver enzyme involved in the metabolism of numerous
medicines), Prof. Zeuzem said that the incidence was likely to have been “a
very low one-digit percentage”. He argued that the main issue regarding
ritonavir-related drug interactions was the need for medical education to
ensure that physicians, especially hepatologists unfamiliar with ritonavir,
understood the potential interactions.
He pointed out that some of the drugs that interact with ritonavir, such
as statins, could be safely interrupted for 12 weeks, or patients could be
switched to other drugs that do not have problematic interactions with
ritonavir.
AbbVie’s three-drug combination is due to be submitted for marketing approval
in the United States and European Union imminently, and the company hopes to achieve
United States marketing approval before the end of 2014.