Taribavirin Comparable in Efficacy to Ribavirin and Results in Less Anaemia in Patients With Chronic Hepatitis C: Presented at EASL

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Title: Taribavirin Comparable in Efficacy to Ribavirin and Results in Less Anaemia in Patients With Chronic Hepatitis C: Presented at EASL
URL: http://www.pslgroup.com/dg/220602.htm
Doctor's Guide
April 29, 2008

By Emma Hitt, PhD

MILAN, Italy -- April 29, 2008 -- Taribavirin, an oral prodrug of ribavirin (RBV), appears to be as effective as RBV in achieving viral response at weeks 4 and 12 when used in combination pegylated interferon (PEG-IFN) alfa-2b in patients with chronic hepatitis C, according to week-12 data.

Fred Poordad, MD, Chief of Hepatology, Center for Liver Disease and Transplantation, Cedars-Sinai Medical Center, Los Angeles, California, presented the findings of the phase 2b trial in a late-breaking abstracts session on April 26 here at the 43rd Annual Meeting of the European Association for the Study of the Liver (EASL 2008).

Taribavirin is thought to cause less haemolysis of red blood cells than RBV and to consequently lower rates of anaemia.

Previously, the phase 3 Viramidine Safety and Efficacy Versus Ribavirin-1 and -2 (VISER1 and VISER2) fixed-dose studies of taribavirin at doses of 13 to 18 mg/kg/day indicated that higher weight based dosing of taribavirin might produce better efficacy," Dr. Poordad said.

In the current study, the researchers compared the efficacy and safety of weight-based dosing of taribavirin versus RBV at week 12 of treatment.

A total of 275 treatment-naive patients with HCV genotype 1 were randomised to receive taribavirin at doses of 20, 25, or 30 mg/kg/day in combination with 1.5 mcg/kg of PEG-IFN alfa-2b weekly. A control arm of RBV 800 to 1400 mg/day plus PEG-IFN alfa-2b was also included in the 4-arm trial. Treatment is planned to continue for 48 weeks with 24 weeks of follow-up. The current report includes preliminary results up until week 12 of treatment.

Viral response with taribavirin was comparable to response to RBV across all treatment arms. Undetectable HCV RNA at week 4 was achieved in 16.4%, 14.3%, and 16.2% of the 20-, 25-, and 30-mg/kg/day taribavirin arms, respectively, and in 11.1% of patients in the control arm. At week 12, at least a 2-log₁₀ decrease in HCV RNA was observed in 64.2%, 57.1%, and 54.4%, respectively, of the taribavirin arms versus 51.4% in the control arm.

A compete early virologic response (EVR) at week 12 was noted in 41.8% and 41.1% of the 20- and 25-mg/kg/day taribavirin arms, respectively. In the 30-mg/kg/day arm, the EVR was slightly less, at 25%, possibly due to dose reductions in this arm, Dr. Poordad noted. In the control arm, 31.4% achieved an EVR.

The number of treatment discontinuations was similar across treatment arms, at about 10% to 20%. A change in dose was more likely to occur in the RBV and taribavirin 30-mg/kg/day arms (>25%) than in the lower-dose taribavirin arms (11%-15%).

The incidence of anaemia was significantly lower with taribavirin than with RBV. The rate was 24.3% in the RBV arm, while in the 20-, 25-, and 30-mg/kg/day taribavirin arms, the incidences were 9.0% (P < .022 vs RBV), 7.1% (P = .009 vs RBV), and 14.7% (P not significant), respectively.

Other treatment-related adverse events were generally as expected with IFN-based treatment. More diarrhoea was associated with taribavirin, observed in about a third of patients, compared with a rate of 17% in the RBV arm. "But this was mild and not treatment-limiting," Dr. Poordad noted.

"Overall, taribavirin demonstrated comparable early efficacy and substantially lower anaemia than RBV. Further evaluation of weight-based taribavirin dosing is warranted," he concluded.

[Presentation title: Treatment Week 12 Results of Weight-Based Taribavirin Versus Weight-Based Ribavirin, Both With Peginterferon Alfa-2b, in Naive Chronic Hepatitis C, Genotype 1 Patients. Abstract 996]

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