Exclusive - U.S. senators want probe of Allergan transfer deal with tribe: letter

By Jan Wolfe

(Reuters) - Four U.S. senators have asked the Senate Judiciary Committee to launch an investigation into a deal drugmaker Allergan Plc struck with a Native American tribe to protect some of its patents from generic challenge, according to a letter seen by Reuters.

Democrats Maggie Hassan, Sherrod Brown, Bob Casey and Richard Blumenthal in the letter to Judiciary Committee Chairman Chuck Grassley and Ranking Member Dianne Feinstein on Wednesday called Allergan's deal "a blatantly anti-competitive attempt to shield its patents from review and keep drug prices high."

Allergan said on Sept. 8 that it was transferring patents on its dry eye medication Restasis to upstate New York's Saint Regis Mohawk Tribe, which agreed to exclusively license them back to the company in exchange for ongoing payments.

Allergan said in an emailed response to a Reuters request for comment that last week Allergan provided Senator Hassan's staff with a briefing on the agreement. "We would welcome the opportunity to provide the Senator with additional details and answering any questions the Senator may have," the company said.

The tribe and company have said that the tribe's sovereign status shields the patents from review by the U.S. Patent Trial and Appeal Board, an administrative court empowered to invalidate patents.

On Friday, the tribe asserted this immunity in an ongoing administrative proceeding brought by generic drugmakers led by Mylan NV , which are seeking to invalidate Allergan's patents to introduce cheaper versions of Restasis to the market. Allergan has said it would not invoke the tribe's immunity in an ongoing federal court case on the same issues.

(Reporting by Jan Wolfe; Editing by Anthony Lin)