WARRENDALE — A privately held pharmaceutical company has been sold, but its staff and facilities will remain here.

Three Rivers Pharmaceuticals, founded by Butler-native Jeffrey Fisher and four other investors in 2000, has been sold to Kadmon Pharmaceuticals in New York City.

Three Rivers is in Thorn Hill Industrial Park, which is in Cranberry Township, Butler County, and Allegheny County.

Dave Pitts, a Kadmon spokesman, said the more than 100 employees of Three Rivers will stay on the job as Kadmon takes over. Also, the Three Rivers headquarters will become the base of operations for Kadmon.

Kadmon is headed by Dr. Samuel Waksal, former CEO of ImClone Systems, whose insider stock tips led to prison sentences for him and Martha Stewart, home living expert.

Fisher, 48, whose parents Robert and Nancy Fisher, own Fisher's Towing and service station on Main Street, Butler, graduated from Butler High School in 1980 and from Duquesne University in 1984 with a pharmacy degree.

His development of a drug to fight Hepatitis C, ribavirin, sold under the brand name Ribasphere, helped to launch Three Rivers.

While Fisher of Gibsonia was unavailable for comment, his mother said today he has been serving as a Three Rivers board member and has a private consulting firm.