USSC Agrees to Reconsider Amgen Inc. v Sanofi on Enablement of Antibody Genus Claims

November 16, 2022
By: Melanie Szweras, Ian McMillan, and Nicole LaBerge

The United States Supreme Court (USSC) recently agreed to review the Court of Appeals for the Federal Circuit’s decision in Amgen Inc. v Sanofi.[1] The court will consider whether patent specifications must teach persons skilled in the art to “reach the full scope” of an invention “without undue experimentation”, or whether it is sufficient for skilled persons to be able to “make and use” that invention. The decision to review the ruling is significant as patents for biologics and other pharmaceuticals in the United States, which often use functional limitations in the claims, face scrutiny regarding written description and enablement requirements (see our article here). The Amgen Inc. v Sanofi decision in particular, appears to undermine the promotion of innovation through the patent system by making it impossible to obtain effective patent protection for some inventions. This may be why the USSC decided to hear the case, despite the Solicitor General’s recommendation to deny the petition.  In addition to the life sciences, the USSC’s decision could potentially influence enablement requirements in other technical fields, where claims often use functional language.

The Dispute

The case concerns competing cholesterol-lowering drugs Repatha® and Praluent®. Amgen owns United States patents 8,829,165 (the ‘165 patent) and 8,859,741 (the ‘741 patent) which describe monoclonal antibodies that bind to the enzyme PCSK9 inhibiting it from binding to low-density lipoprotein (LDL). This binding event prevents LDL receptor degradation, resulting in lower bloodstream cholesterol. The claimed antibodies are defined by their dual function; they bind to a combination of amino acids (“residues”) on the PCSK9 protein and block the PCSK9/LDL receptor interaction. Each of the ‘165 and ‘741 patents has the same written description. The specification discloses amino acid sequences for twenty-six antibodies, including the antibody Evolocumab, marketed by Amgen as Repatha®. The ‘165 specification discloses the three-dimensional structure of Repatha® and where it binds to PCSK9. Both patents claim antibodies that bind to one or more of fifteen residues found within the PCSK9 protein, blocking PCSK9 from binding to LDL receptors.

An exemplary claim from the ‘165 patent is reproduced below:

An isolated monoclonal antibody, wherein, when bound to PCSK9, the monoclonal antibody binds to at least one of the following residues: S153, I154, P155, R194, D238, A239, I369, S372, D374, C375, T377, C378, F379, V380, or S381 of SEQ ID NO:3, and wherein the monoclonal antibody blocks binding of PCSK9 to LDLR. (Emphasis added).

Procedural History

The dispute began in 2014, when Amgen alleged Sanofi and Regeneron (collectively, “Sanofi”) infringed the ‘165 and ‘741 patents with their competing drug Praluent®.[2] Amgen and Sanofi stipulated to infringement of selected claims and tried issues of validity. The case was tried by a jury. The District Court of Delaware granted judgment as a matter of law (JMOL) of non-obviousness and no willful infringement.[3] The jury determined the patents were not shown to be invalid for lack of enablement and written description.[4]

Sanofi appealed and the Court of Appeals held the District Court erred in its evidentiary findings and jury instructions regarding Sanofi’s defences that the patents lack written description and enablement.[5] The case was sent back for a new trial. On remand, a second jury considered the issues of written description and enablement where they once again found that Sanofi failed to prove that the asserted claims were invalid for lack of written description and enablement.[6] Following this, Sanofi moved for a JMOL and in the alternative for a new trial.[7] The District Court granted Sanofi’s motion for JMOL for lack of enablement and denied the motion for lack of written description.[8] Amgen subsequently appealed where the matter proceeded to the Court of Appeals for a second time.

The Decision on Appeal

35 U.S.C § 112 of the Patent Act requires a patent’s specification to “enable any person skilled in the art…to make and use” the patented invention. In assessing enablement, it has been held that the disclosure must be “at least commensurate with the scope of the claims.” To invalidate a claim for lack of enablement, “a challenger must show by clear and convincing evidence that a person of ordinary skill in the art (POSITA) would not be able to practice the claimed invention without ‘undue experimentation’”.[9]

In re Wands sets out the factors that a court may consider “when determining whether the amount of that experimentation is either ‘undue’ or sufficiently routine such that an ordinarily skilled artisan would reasonably be expected to carry it out”.[10] Amgen argued that the court erred by considering the effort required to discover and make every embodiment of the claims.[11] (Emphasis added).

The Court of Appeals first reviewed its previous decisions on enablement stating that “what emerges from our case law is that the enablement inquiry for claims that include functional requirements can be particularly focused on the breadth of those requirements, especially where predictability and guidance requirements fall short”.[12]

Next, the court considered the relevant Wands factors.

Breadth of the Claims:  The Court of Appeals agreed with the District Court that the scope of the claims was indisputably broad. Rather than focusing on the number of embodiments disclosed, the Court of Appeals was concerned with their functional breadth. They found the claims were far broader in functional diversity than the disclosed examples.

Predictability or Unpredictability of the Art: Agreeing with the District Court, the three-judge panel held the invention is in an unpredictable field of science. Only a small subset of examples of antibodies can predictably be generated. Further, they noted that the disclosed roadmap for producing claimed antibodies combined with the unpredictability of the art would force a fact finder to conclude that the patents fail to provide any significant guidance or direction to a POSITA.

Quantity of Experimentation Necessary:  The Court of Appeals found that undue experimentation was required to arrive at embodiments outside the scope of the disclosed examples. They agreed with the District Court that the only way a POSITA would discover the undisclosed claimed embodiments would be through either “trial and error, by making changes to the disclosed antibodies and then screening those antibodies for the desired binding and blocking properties” or else, “by discovering the antibodies de novo” according to a randomization-and-screening “roadmap”.[13]

In view of the above, the Court of Appeals affirmed the District Court’s ruling that undue experimentation would be required to practice the full scope of the claims. Amgen subsequently filed a writ of certiorari to the USSC.

The Supreme Court’s Decision and its Broader Implications

The USSC’s decision has the potential to clarify the law on the enablement requirement, which has not been addressed for a long time. The Court of Appeals decision emphasized that the field was unpredictable, perhaps holding Life Science cases to a different standard. As it stands, the Court of Appeals’ application of § 112 to the claims in Amgen Inc. v Sanofi largely differs from its application in the mechanical arts and IT fields.[14] Moreover, “means plus function claims” and “product by process” claims that are used to protect subject matter where its structure is unknown have not seen such a strict application of the enablement doctrines. For instance, a “means plus function” claim is valid if the specification contains support for the structures that define the means. The broadest reasonable interpretation of a means plus function claim will therefore be drawn to the structure, material or acts described in the specification and their equivalents (MPEP 2181).

If the USSC upholds the decision, they risk placing too strict a focus on the full scope of the claim rather than on what the POSITA could determine from the specification. Not only will this render the US an outlier when it comes to protecting antibodies, it may also create uncertainty for patentees in other fields. For example, it is unclear what this would mean for computer-implemented inventions, where patent claims often use functional limitations to define the problem to be solved and cover any solution to that problem.[15]  AI inventions in particular may be defined in terms of the “roadmap” sufficient to provide the required AI, instead of in terms of structure shared by any AI thus provided.  It is not clear that broad claims for AI inventions would satisfy enablement requirements if these claims were held to the same standards for enablement as genus antibody claims.

Regardless of the technology at issue, it would be prudent for patentees to build fallback positions into their applications with some expectation that the cases will continue to follow the same pattern. In the antibody space, this may include structural features such as the nucleic or amino acid sequences of the antibodies or their CDR regions. In chemical patents, fallback positions that incorporate claims to specific or narrower embodiments of compounds useful for the purpose of the invention should also be considered. And similarly for computer patents, whenever possible include narrower claims defining specific and/or highly granular steps executed by the computer.[16]


[1] 987 F.3d 1080.

[2] Amgen Inc. v. Sanofi, 227 F. Supp. 3d 333, 336 (D. Del. 2017).

[3] Ibid, at 337.

[4] Ibid.

[5] Amgen Inc. v. Sanofi, 872 F.3d 1367, 1381-82 (Fed. Cir. 2017).

[6] Amgen Inc. v. Sanofi, No. CV 14-1317-RGA, 2019 WL 4058927 (D. Del. Aug. 28, 2019).

[7] Ibid.

[8] Ibid.

[9] Alcon Research Ltd. v. Barr Labs., Inc., 745 F. 3d 1180, 1188 (quoting In re Wands, 858 F.2d 731, 736–37 (Fed. Cir. 1988)).

[10] Ibid.

[11] Supra note 1, at 9.

[12] Ibid at 13.

[13] Ibid at 17.

[14] Dan L. Burk & Mark A. Lemley, The Patent Crisis and How the Courts Can Solve it (2009) at 59-62.

[15] Mark A. Lemley, Software Patents and the Return of Functional Claiming, 2013 Wis. L. Rev. 905, 923; Otis Elevator Co. v. Pac. Fin. Corp., 68 F.2d 664, 669 (9th Cir.)

[16] To reduce the risk of the claims being rejected for lack of subject matter as abstract ideas, the specification should support arguments that these specific and/or highly granular steps “improve the functioning of the computer [or]…other technology or technical field.”  (Alice Corp v CLS Bank International 134 S Ct 2347 (2014) at 2359).

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