Idenix: Early phase 2b data shows valopicitabine with pegylated interferon increases viral suppression in hepatitis C

By E. Janene Geiss

Philadelphia, Dec. 14 - Idenix Pharmaceuticals Inc. said Wednesday that partial 24-week data from an ongoing phase 2b clinical trial evaluating valopicitabine combined with pegylated interferon demonstrate viral suppression in treatment-refractory patients with chronic hepatitis C.

All patients enrolled in this trial are chronically infected with the genotype 1 strain of hepatitis C and have previously failed to respond to treatment with pegylated interferon plus ribavirin, according to a company news release.

This 48-week phase 2b clinical trial is evaluating three dosing regimens of valopicitabine, administered once-daily, in combination with pegylated interferon compared to retreatment with combination therapy of pegylated interferon plus ribavirin.

Valopicitabine combination dosing regimens include valopicitabine 400 mg, valopicitabine ramping from 400 mg to 800 mg during week 1 and continuing thereafter with 800 mg, and valopicitabine 800 mg.

In all three arms, valopicitabine is given in combination with pegylated interferon alfa-2a with the initial dose of pegylated interferon administered on day eight.

The partial 24-week data for 162 patients out of 178 patients demonstrated that the two higher-dose arms of valopicitabine plus pegylated interferon produced greater suppression of serum HCV RNA compared to the ribavirin plus pegylated interferon retreatment control arm.

At week 24, mean HCV RNA reductions in the two high-dose arms of valopicitabine plus pegylated interferon were 3.01 log10 and 3.32 log10, with 11% and 25% of patients achieving undetectable levels of virus, the company said.

In comparison, patients in the pegylated interferon plus ribavirin retreatment control arm showed a mean HCV RNA reduction of 2.31 log10, with 19% of patients achieving undetectable levels of virus.

Patients in valopicitabine-containing arms also demonstrated a more consistent response than patients in the retreatment control arm, Idenix said.

"It is encouraging that we continue to see substantial viral reductions out to week 24 with the valopicitabine and pegylated interferon combination treatment arms in this refractory patient population," said investigator Christopher O'Brien of the University of Miami in the release.

"The consistency of response seen in the individual patient data in the valopicitabine combination arms compared to the control arm suggests that the differential in viral load reductions may continue to widen in favor of the valopicitabine combination arms as treatment progresses."

O'Brien presented the data this week at the Hep DART meeting in Hawaii.

In the trial, valopicitabine has demonstrated satisfactory safety and tolerance overall, the company said.

To date, a low percentage of patients on valopicitabine have discontinued due to adverse events. Four serious adverse events, diverse in nature, were considered attributable to combination treatment with valopicitabine plus pegylated interferon and all cases resolved after discontinuation of treatment.

The company said it anticipates presenting the complete 24-week data from this phase 2b clinical trial at scientific conferences in the spring of 2006.

Idenix is a Cambridge, Mass., biopharmaceutical company focused on development of drugs for the treatment of human viral and other infectious diseases.

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