Legal Alert

Supreme Court Affirms Lack of Enablement for Amgen’s Patent Claims

by Caryn Borg-Breen, Ph.D., Margaret Bolce Brivanlou, Ph.D., Scott D. Marty, Ph.D., Kenneth H. Sonnenfeld, Ph.D., and Alan White, Ph.D.
May 22, 2023


In Amgen v. Sanofi, the Supreme Court unanimously affirmed the District of Delaware and Federal Circuit findings that Amgen’s functionally defined patent claims to a class of therapeutic antibodies are invalid as lacking enablement in the specification. The decision has implications for procurement and enforcement of patents to biotechnology inventions.

The Upshot

  • The Supreme Court held as invalid Amgen’s claims to a genus of antibodies defined by their binding properties and not by their amino acid sequence because the patent specification’s disclosure of exemplary antibodies and methods of identifying others was insufficient to enable the potentially vast number of antibodies encompassed by the claims.
  • Citing more than 100 year-old precedent, Justice Gorsuch wrote for the Court that given the unpredictability in the field of art, Amgen’s disclosure of “roadmap” trial and error methods to make and screen antibodies and “conservative” amino acid substitution strategies were insufficient to enable such functionally defined antibody claims. According to the decision, Amgen’s 26 antibody examples did not support a monopoly to the class of antibodies defined by their function.

The Bottom Line

The decision reflects courts’ increasing focus on support for functionally defined genus claims in the life sciences. The Supreme Court’s affirmance may impact patent prosecution and patent challenge strategies in the biotech space and beyond.

On May 18, 2023, the Supreme Court decided Amgen Inc., et al. v. Sanofi, et al., No. 2-1757, unanimously affirming decisions of the Federal Circuit and the District of Delaware finding for respondents Sanofi and Regeneron that petitioner Amgen’s patent claims directed to a genus of antibodies are invalid for lack of enablement under 35 U.S.C. § 112(a). According to the Court, Amgen’s patent claims did not describe the full scope of the antibody genus according to its structure. Rather, the claims recite functional language, i.e., antibodies that (i) bind to specific amino acids on a naturally occurring protein, and (ii) block the activity of that protein.

The dispute between Amgen and Sanofi centered on a groundbreaking class of antibody drugs that can bind to and inhibit a naturally occurring protein known as PCSK9, which normally acts to prevent cells from absorbing low-density lipoprotein cholesterol (LDL) from the bloodstream. By inhibiting PCSK9, these drugs can reduce the amount of circulating LDL, and thereby lower the risk of cardiovascular disease, heart attacks, and strokes in patients that suffer from high levels of circulating LDL. In 2011, Amgen and Sanofi each obtained separate patents claiming specific antibodies, defined by a unique amino acid sequence, that could bind to and inhibit PCSK9, and thereby reduce LDL levels in patients.

In 2014, however, Amgen obtained two additional patents with broader claims that functionally defined a genus of PCSK9 antibodies that could bind to a specific region of PCSK9, i.e., the “sweet spot,” thereby blocking its activity. Amgen subsequently sued Sanofi for infringing the 2014 patents. The Delaware district court held Amgen’s 2014 patent claims invalid under 35 U.S.C. § 112(a) because, according to the court, the specification failed to enable the full scope of the claimed genus of potential PCSK9 antibody sequences. The Federal Circuit affirmed the district court’s decision, and Amgen appealed to the Supreme Court.

In affirming the invalidity of Amgen’s anti-PCSK9 genus claims for lack of enablement, the Supreme Court noted that “if our cases teach anything, it is that the more a party claims . . . the more it must enable,” and that while Amgen’s claims encompassed “millions” of antibodies with the potential to bind and inhibit PCSK9, the specification only identified the amino acid sequences of 26 specific anti-PCSK9 antibodies known to do so. The Court rejected Amgen’s argument that the specification was enabling because it provided a “roadmap” of experiments to identify antibodies that bind to the PCSK9 “sweet spot” and inhibit PCSK9, and also outlined a strategy of “conservative” amino acid substitutions that could be used to predict which antibodies would have the desired functional properties. Labeling these “little more than two research assignments,” the Court observed that the “roadmap” merely described Amgen’s own trial-and-error method for discovering PCSK9 antibodies, and that the “conservative substitution” method simply provided candidate antibodies that still had to be tested for their ability to bind to and inhibit PCSK9. In addressing whether the disclosure of methods like a “roadmap” or “conservative substitution” might suffice to enable other claims in other patents, the Court noted that whether “the inventor identifies a quality common to every functional embodiment” could be of import to an enablement analysis. For the case at hand, the Court found that Amgen failed to supply such information, likening the disclosure of the 26 PCSK9 antibodies to disclosing only 26 functional combinations of a lock that has millions of possible non-functional combinations. Finally, the Court rejected Amgen’s argument that affirming the invalidity decisions below would destroy incentives for developing similar breakthrough drugs, noting that the lower courts had properly applied 35 U.S.C. § 112(a), and that it was up to Congress to judge whether the outcome reflects the appropriate incentive for future innovators.


When considering patent claims covering therapeutics that act by binding to a specific binding site, the Court’s decision in Amgen v. Sanofi, rejecting the identification of a binding target “sweet spot” as being sufficient to enable all other antibodies that also bind to the same target, should be considered along with the Federal Circuit’s decision in Juno Therapeutics, Inc. v. Kite Pharma, Inc., No. 20-1758 (Fed. Cir. 2021)—a case where the Supreme Court twice denied petitions for certiorari—invalidating claims to biologics lacking target binding structural elements as failing to have an adequate written description. Taken together, these two cases highlight the importance courts are giving to the adequacy of the teachings in patents claiming more than that which is explicitly exemplified in the specification.

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