Schering-Plough Corp. said Wednesday that it sued GenentechInc., seeking to invalidate a Genentech patent and lifting anyclaim to sales of Schering's Intron-A recombinant alphainterferon.

Schering's suit, which was filed Tuesday in U.S. District Court inNewark, N.J., claims that Genentech's U.S. patent No. 4,704,362is invalid and unenforceable. Schering of Madison, N.J., said itsaction follows a similar suit filed by Eli Lilly & Co in U.S. DistrictCourt in Indianapolis to invalidate Genentech's patent. Thatcase has been consolidated with Genentech's cross-suit againstLilly, a Genentech spokeswoman said.

Genentech said Wednesday that it had not yet received a copyof Schering's suit, but issued a statement: "Genentech believesthe patent is valid and is interfered and infringed by Schering'ssale of Intron-A." Genentech of South San Francisco, Calif., saidit has licensed use of the patent to 30 companies.

Genentech threatened to sue Schering in January 1991,claiming that Schering's use of certain intermediates inproducing alpha interferon infringed the Genentech patent,according to Schering spokesman Steve Galpin Jr.

Schering reported $251 million in worldwide sales of Intron-Ain 1991. The drug is approved for sale in 58 countries as atreatment for as many as 16 indications. It is approved in theUnited States for treating hairy cell leukemia, Kaposi's sarcoma,venereal warts and hepatitis C.

Schering's sales of alpha interferon are covered under a cross-licensing agreement with Hoffmann-La Roche, which marketsanother alpha interferon product, Roferon-A, Galpin said.

Genentech shares (NYSE:GNE) dropped $1 to $31.38 onWednesday. -- Ray Potter

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