Amgen Inc. may sue Maxygen Inc. for patent infringement over a drug used to treat a disease associated with a low white blood cell count, Maxygen said in a filing Friday.
Shares in the Redwood City-based biotech company dropped as much as 30 percent after word of the potential suit was released.
Amgen was granted a patent by the FDA June 3 with claims to certain hybrid molecules, Maxygen said, and Amgen may sue for patent infringement if Maxy-G34 goes on sale.
Maxygen, which holds four other patents related to the drug has a “viable defense” and will “vigorously defend” against any infringement claims, the company said in the filing.
Shares in Amgen closed up 1.7 percent to $43.97 Friday.