(Adds analyst comments, share activity)
By Lawrence Hurley
WASHINGTON, March 31 (Reuters) - The U.S. Supreme Court on Monday agreed to hear an appeal filed by Teva Pharmaceutical Industries Ltd in a patent fight over top-selling multiple sclerosis drug Copaxone, a move that could deter generic manufacturers from introducing cheaper versions onto the market as soon as May.
By agreeing to hear the case, the high court cast into doubt a July 2013 ruling by the U.S. Court of Appeals for the Federal Circuit in favor of two teams developing cheaper generic forms of Copaxone: one involving Novartis AG's Sandoz Inc and Momenta Pharmaceuticals Inc and another involving Mylan Inc and Natco Pharma Ltd.
"This is great news for Teva, as we believe it will bolster investor confidence that a generic will not be on the market in May 2014, as Momenta and Mylan, even if approved in May, may not be willing to risk a launch," David Maris, an analyst with BMO Capital Markets, said.
Shares of Israel-based Teva rose 5.04 percent to $51.94 in afternoon trading on the New York Stock Exchange.
The appeals court had upheld some of nine patents involved in the drug, or portions thereof, but declared several invalid, meaning patent protections were set to expire in May 2014 instead of September 2015.
With that outcome now uncertain, Teva likely has more time to switch patients over to a new version of the medicine. Copaxone, the leading treatment for multiple sclerosis, has been by far Teva's most important product.
Even though Teva is the world's largest maker of generic drugs, its branded Copaxone has accounted for about 20 percent of company sales and 50 percent of its profits.
In late January, the U.S. Food and Drug Administration approved a new version of Copaxone that is taken three times a week instead of daily.
Teva has said it believes it will be able to get 45 percent of regular Copaxone patients to switch to the new drug. However, it is critically important to get as many patients switched over as possible before cheap generic versions of the original Copaxone begin to flood the market.
Analysts have said Teva's strategy of switching patients to the more convenient three-times-a-week Copaxone is going well so far.
"Our recent multiple sclerosis survey indicates that 25 percent of current Copaxone patients will be switched by June, about 33 percent by year end and 40 percent in two years," Jason Gerberry, a Leerink Partners analyst, said in a research note.
"Further, we've gotten feedback from payers that they won't force patients off three-times weekly if a generic 20 mg (daily Copaxone) becomes available, so we view near-term conversion rates as a key determinant of the future generic market size," he added.
Oral arguments and a ruling are expected in the court's next term, which begins in October and ends in June 2015.
Louise Chen, an analyst with Guggenheim Partners, said if Teva files for and receives an injunction in the meantime, the generics could not launch even if approved in May.
The case is Teva v. Sandoz, U.S. Supreme Court, 13-854.
Reporting by Lawrence Hurley; Additional reporting by Bill Berkrot and Susan Kelly; Editing by Howard Goller and Leslie Adler