Amgen Inc. is confronting a significant legal challenge as the U.S. Court of Appeals invalidated its patents on the cholesterol-lowering drug Repatha, threatening nearly $1.3 billion in sales. Sanofi has labeled Amgen's attempt to revive these patents as a blatant strategy to eliminate competition from rivals like Regeneron, which earned $130 million from its competing drug, Praluent. The Biden administration has sided with Sanofi, complicating Amgen's appeal process, with a decision anticipated by the end of June.