Schering-Plough says hepatitis C data positive

BOSTON, Nov. 1 (Reuters) - Schering-Plough Corp SGP.N said its experimental drug to treat hepatitis C is more effective in eradicating the virus in previously untreated patients than standard therapies for the serious liver disease.

Data released on Saturday at the annual meeting of the American Association for the Study of Liver Diseases in San Francisco showed that the drug, boceprevir, when given in combination with the standard treatments peginterferon and ribavirin, was more effective than the standard treatment alone.

The main goal of the 595-patient trial, known as SPRINT-1, was to establish the rate at which patients maintain a sustained viral response (SVR), defined as the eradication of the virus to undetectable levels, at 24 weeks following the end of treatment.

The company said that 24 weeks after a 28-week period of treatment, 56 percent of patients had no detectable virus in their system. That compared with 38 percent for those who took the standard treatment alone. Patients in the boceprevir arm received four weeks of standard therapy followed by 24 weeks of triple combination treatment.

For patients who did not receive the four-week lead-in treatment, but took the triple combination for all 28 weeks, the SVR rate was 55 percent.

Schering-Plough said the trial has not been going on long enough to show the SVR rate at 24 weeks following 48 weeks of treatment, which is the typical length of time needed for existing treatments to work.

Schering-Plough and rival Vertex Pharmaceuticals Inc (VRTX.O), which is developing a competing drug called telaprevir, hope to reduce the time needed for treatment by as much as half.

At 12 weeks after the end of 48 weeks of treatment, including a four-week lead-in time, the boceprevir SVR rate was 74 percent. That compared with a rate of 66 percent for patients who took the triple combination regime for all 48 weeks, with no lead-in period. The SVR rate in the control group was 38 percent.

Fewer patients in the lead-in arms discontinued treatment due to viral breakthrough compared with those who did not have a lead-in period.

The company said the rationale for the lead-in treatment regimen is based on the fact that both peginterferon and ribavirin reach steady concentrations by week four, so patients have the new drug added at a time when the standard care drug levels have been optimized.

The most important side effects in the boceprevir arms of the trial were fatigue, anemia, nausea and headache, the company said. There was no increase in skin disorders such as rash, which has been a concern with telaprevir.

Boceprevir and telaprevir work by inhibiting an enzyme essential for the virus to replicate.

Hepatitis C is a blood-borne liver disease that can cause chronic liver disease, liver cancer and cirrhosis. It affects about 3.4 million people in the United States. (Reporting by Toni Clarke, editing by Richard Chang)