Treating hepatitis B patients with
hepatitis delta virus (HDV) co-infection using pegylated interferon plus
tenofovir (Viread) for 96 weeks may
reduce HDV viral load, but side-effects are frequent and it did not
significantly improve the likelihood of HBsAg reduction, according to a report
at the 49th Annual Meeting of the European Association for the Study of the Liver (EASL)
last week in London.
Hepatitis delta is the most severe form of chronic
viral hepatitis. HDV is a defective virus that can only complete its lifecycle
in the presence of hepatitis B virus (HBV). HDV and HBV are transmitted in
similar ways and an estimated 15 million people are co-infected with both, with
the highest prevalence in regions where hepatitis B epidemics are primarily related to
injection drug use including Russia, Romania and
the Mediterranean countries. Antiviral drugs
such as tenofovir or entecavir (Baraclude)
that suppress HBV viral load do not stop HDV replication, so people with this co-infection
remain at risk for complications such as liver cirrhosis.
Heiner Wedemeyer from Hannover Medical School in Germany and fellow
investigators with HIDIT-2 (the Hep Net International Delta Intervention Trial
2) evaluated the efficacy and tolerability of prolonged treatment of hepatitis
delta using pegylated interferon with or without tenofovir.
The HIDIT-1 study previously showed
that pegylated interferon for 1.0 to 1.5 years is effective in 25 to 30% of
treated patients, but HBV polymerase inhibitors do not suppress HDV RNA, the
researchers noted as background. HIDIT-2 aimed to determine if extending
treatment to two years could improve response rates, in particular sustained
response as measured 24 weeks after the end of therapy.
HIDIT-2 was actually two parallel
trials with identical protocols and a combined analysis. One study included 70
patients with detectable HDV RNA recruited in Germany, Greece and Romania,
while the other enrolled 50 patients in Turkey. A majority were men, the mean
age was 40 years, about 15% were hepatitis 'e' antigen (HBeAg) positive and 40%
had cirrhosis; people with decompensated liver diseases were excluded, as this
is a contraindication for interferon. People triply infected with hepatitis C
or HIV also were not included. About half had previously been treated with interferon.
Participants were randomly assigned
to receive 180mcg weekly pegylated interferon alfa-2a (Pegasys) injections plus once-daily oral tenofovir or placebo for
96 weeks. Pegylated interferon stimulates the body's immune response against
viruses, while tenofovir directly interferes with viral replication.
At the end of 96 weeks of treatment,
47% of patients taking pegylated interferon plus tenofovir had undetectable HDV
RNA, compared with 33% of those taking interferon plus placebo – a numerical
advantage but not statistically significant (p = 0.10). In a per protocol
analysis of those who completed treatment, the corresponding rates were 54 and
41%, respectively, also not significant (p = 0.19).
After finishing treatment, 44% of
patients in the combination arm and 40% in the interferon + placebo arm with
end-of-treatment response experienced relapse. However, one and three patients
in the two arms, respectively, reached undetectable HDV RNA after stopping
therapy. This resulted in 24-week post-treatment sustained response rates of
30% in the combination arm and 23% in the placebo arm, again not a significant
difference (p = 0.34).
Just over 30% of patients in the
combination arm and about 25% in the placebo arm experienced a hepatitis B
surface antigen (HBsAg) decline of >0.5 log IU/ml by week 96; this fell to
about 22% in the combination arm and remained stable in the placebo arm at week
120.
Lower HDV RNA and lower HBsAg levels
at baseline were associated with HDV sustained virological response. People
with cirrhosis also had a higher HDV virological response rate compared with people who did not have cirrhosis (51 vs 25%, respectively).
Prolonged pegylated interferon plus
tenofovir was difficult to tolerate and 20 patients – about equally distributed
between the two arms – did not complete at least 80 weeks of treatment. All
participants had at least one adverse event and one-third had serious adverse
events.
"96 weeks of [pegylated
interferon alfa-2a] and tenofovir therapy is possible but associated with
frequent serious adverse events," the researchers concluded.
"Combination treatment showed numerically higher rates of on-treatment HDV
RNA suppression but similar effects on HBsAg reductions as compared to
[pegylated interferon alfa-2a] alone."
"Patients with hepatitis delta
and compensated liver cirrhosis should be treated with [pegylated interferon
alfa-2a]," they recommended. However, they added, "combination
therapy with tenofovir does not provide obvious benefits in hepatitis delta
patients with low baseline HBV DNA levels" and "96 weeks of
[pegylated interferon alfa-2a] treatment does not provide higher post-treatment
HDV RNA responses (compared to 48 weeks in the HIDIT-1 study)."
Speaking from the audience, Mario Rizzetto
from the University of Torino, whose team discovered HDV in 1977, said that this
study "confirms what we already know" – that relapse usually occurs
after stopping treatment.
The researchers concluded that,
"Alternative treatment options are urgently needed for HDV-infected
patients." Wedemeyer noted that EASL will help fund the Hepatitis Delta International Network to enable more research on this difficult-to-treat
virus.