SciClone says second phase 3 hepatitis C trial for Zadaxin fails to meet endpoint

By E. Janene Geiss

Philadelphia, May 25 - SciClone Pharmaceuticals, Inc. said Thursday that final results from its second U.S. phase 3 hepatitis C virus trial indicate that treatment with Zadaxin plus pegylated interferon alpha did not demonstrate a statistically significant improvement compared with treatment with pegylated interferon alpha alone in sustained virologic response, the trial's primary endpoint, according to a company news release.

The trial had evaluated the benefit of adding Zadaxin to pegylated interferon alpha treatment for hepatitis C patients with early cirrhosis of the liver who have failed prior therapy.

Zadaxin was generally well-tolerated with no treatment-related toxicities or side effects.

SciClone said the final results from its first U.S. phase 3 hepatitis C trial reported in December were consistent with these results and not statistically significant.

"Given these results, our Zadaxin development efforts will be focused on advanced-staged malignant melanoma in conjunction with our European development and marketing partner, Sigma-Tau," Ira D. Lawrence, president and chief executive officer of SciClone, said the release.

Further development of Zadaxin in hepatitis C will be dependent on the results achieved from the ongoing triple therapy hepatitis C trial being conducted by Sigma-Tau in Europe that are expected in 2008, officials said.

In addition to developing Zadaxin as a treatment for melanoma, the company's clinical development plans include a proprietary drug candidate, SCV-07, which has demonstrated broad therapeutic applicability in a variety of viral and other infectious diseases.

Currently, the company said it is conducting an oral comparison study with SCV-07 to determine its availability when administered orally.

The company said it expects to begin a proof-of-concept clinical trial to evaluate the potential benefit of SCV-07 in an influenza vaccine dose sparing setting in the second half of this year.

Hepatitis C patients in this second U.S. phase 3 clinical trial received a 48-week course of therapy of either Zadaxin (1.6 mg, twice a week) and pegylated interferon alpha (180 mcg, once a week) or a placebo and pegylated interferon alpha followed by a 24-week observation period. The trial's primary endpoint was the achievement of sustained virologic response at week 72, officials said.

Sigma-Tau is conducting a hepatitis C trial in Europe to evaluate the efficacy of a triple therapy combination of Zadaxin, pegylated interferon alpha and ribavirin.

Results from this trial are not expected until 2008, officials said.

The Food and Drug Administration and the European Medicines Agency generally require two confirmatory phase 3 clinical trials to support a regulatory filing. Should the results of this European triple therapy trial be statistically significant, they will likely be insufficient for a regulatory filing and statistically significant results from a second triple therapy trial would be needed, officials said.

SciClone is a San Mateo, Calif., biopharmaceutical company.

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