UPDATE 2-UK trust sues Amgen, Wyeth over Enbrel patent

WILMINGTON, Del., Oct 28 - A British charitable trust filed a patent infringement suit against Wyeth and Amgen on Wednesday over their blockbuster Enbrel drug, one of the world's best-selling treatments for rheumatoid arthritis.

The Mathilda and Terence Kennedy Institute of Rheumatology Trust asked a federal court in Delaware to grant royalty payments and damages from Wyeth and Amgen for infringing a patent for treating arthritis.

Enbrel garners billions of dollars in annual sales for Amgen Inc and Wyeth, which for years have co-marketed the drug. Wyeth was acquired this year by Pfizer Inc, the world's largest drug company.

The trust said in the complaint that its 2001 patent was developed by Marc Feldmann and Ravinder Maini, both with the Imperial College London.

The trust's patent relates to treating arthritis by co-administering methotrexate and drugs that block receptors to an inflammation-causing protein called tumor necrosis factor alpha (anti-TNFa) such as Enbrel, according to court documents.

Amgen and Wyeth have refused demands for royalty payments, the complaint said. The Enbrel website says the drug can be used in combination with methotrexate.

Centocor, a unit of Johnson & Johnson, and Abbott Laboratories Inc are the two other main distributors of drugs that employ anti-TNFa receptors. Both have paid the trust tens of millions of dollars in royalty payments, the complaint said.

"Amgen believes we do not infringe or induce infringement of any valid enforceable claim of this patent," said Amgen spokesman David Polk, who described the trust's claims as "meritless."

"We support Amgen's position," a spokeswoman for Pfizer said.

An attorney for the trust did not return calls for a comment.

Amgen shares were off 27 cents or 0.5 percent at $54.14 and Pfizer shares were up 3 cents or 0.2 percent at $17.29.

The case is The Mathilda and Terence Kennedy Institute of Rheumatology Trust, U.S. District Court for the District of Delaware, No. 09-00805.