Updated from 3:51 p.m. EDT
shares closed up 5% higher after a federal judge sided with the California biotechnology company in a patent infringement lawsuit against
and its marketing partner
Amgen shares closed up 2 15/16, or 5%, at 57 1/4. Transkaryotic shares fell 13%, down 4 1/8 at 278. Franco-German drugmaker Aventis shares closed down 1/16, or 0.5%, at 56 5/8.
U.S. District Judge William G. Young granted Amgen's request for a summary judgement that Transkaryotic infringed on one patent covering Epogen, Amgen's blockbuster blood-building drug. However, the judge allowed Transkaryotic to seek to overturn Amgen patents in a trial slated for May 15, over which he will preside.
Transkaryotic and Aventis are seeking to market GA-Epo, their own version of the drug, which is used by cancer and kidney patients to grow red blood cells. Epogen generated $1.7 billion in 1999 and is the Thousand Oaks, Calif.-based company's biggest selling product.
Transkaryotic said it remained "confident" of its legal position. "We believe we have compelling arguments," said Justine Koenigsberg, spokeswoman for Cambridge, Mass.-based Transkaryotic.
Amgen filed 18 patent claims against Transkaryotic. Judge Young ruled that Transkaryotic infringed one of them, No. 422.
Analysts said the victory was important for Amgen, although it seemed increasingly likely that the company would prevail.
"I think people misunderstood how weak the Transkaryotic position has been," said David Saks, chief investment officer for
Gruntal MedSciences Fund
. "Amgen had to come out winning here."
Nonetheless, he said Transkaryotic has much to gain from challenging Amgen and its franchise on a lucrative market. Amgen markets Epogen for the treatment of anemia associated with chronic renal failure for people on kidney dialysis. It is also used with chemotherapy in cancer patients. It is the only such product on the market.
"TKT was taking a crack, a calculated gamble, which has a huge upside and only lawyer fees on the downside," said Saks.
"We are pleased with the court's ruling," said Gordon Binder, Amgen chief executive and chairman. "This is a first but important step in the final determination of Amgen's claims."