InterMune Hep C Drug Hit With Liver Tox Worry: BioBuzz

BRISBANE, Calif. (TheStreet) -- A potential liver toxicity problem has cropped up with InterMune's(ITMN Quote) experimental hepatitis C drug, forcing the company to make a change to an ongoing mid-stage study.

Three patients being treated with InterMune's ITMN-191 at a twice-daily dose of 900 mg experienced significant elevations in liver enzymes that can be a signal for liver damage, the company said Tuesday.

As a result, independent safety monitors recommended that the twice-daily, 900-mg dose arm of the ITMN-191 study be discontinued. Patients will continue to be treated with ITMN-191 at lower doses in the remaining arms of the study.

InterMune shares were down 11% to $12.50 in pre-market trading Tuesday.

ITMN-191 is an experimental protease inhibitor against the Hep C virus -- the same class of direct antiviral drug as Vertex Pharmaceutical's(VRTX Quote) telaprevir.

The study in which the signal for liver toxicity appeared involves treatment with ITMN-191 in combination with the current standard of care, long-acting interferon and ribavirin. Early efficacy results from this study are expected in the first quarter of next year.

Roche is InterMune's global development partner for ITMN-191. As part of this collaboration, ITMN-191 is being studied in combination with another experimental Hep C drug from Pharmasset(VRUS Quote). That study, known as INFORM-1, also treats patients with a 900 mg dose of ITMN-191, but to date, no signal of liver toxicity has been reported.

-- Reported by Adam Feuerstein in Boston