In the case, Amgen v. Sanofi, the Court vacated an injunction Amgen obtained against a competing drug to its new PCSK9-inhibitor. The Court’s decision turned on a finding that the jury was improperly instructed on the criteria for invalidating a patent directed to an antibody for lack of written description. Thus, will the precedent recently established in Amgen’s PCSK9 case doom the validity of its patents covering Enbrel®? There are likely two ways that the decision in Amgen v. Sanofi made a validity challenge to Enbrel®’s patents easier.