Coherus Biosciences Inc. said its petitions to invalidate Amgen Inc.'s patents covering etanercept were rejected by the U.S. Patent Trial and Appeal Board.
Etanercept is the main component of Amgen's rheumatoid arthritis drug Enbrel.
The Redwood City, Calif.-based biotechnology company was seeking to invalidate the patents in the interest of its biosimilar, CHS-0214.
The patents flagged for inter partes review cover a method for making etanercept and also the protein itself.
Amgen's patent for the medicine does not expire until 2029.
