Amgen v Sanofi (US Supreme Court, No 21-757, 2023)

Dhenne Avocats · 11 October 2026

Our analysis

Summary

A unanimous US Supreme Court (opinion of Justice Gorsuch) upheld the invalidity, for lack of enablement, of Amgen claims covering in functional terms every antibody that binds to a specified site on the PCSK9 protein and blocks it from binding to LDL cholesterol receptors. Where a patent claims an entire class, the specification must enable a person skilled in the art to make and use the entire class; the more one claims, the more one must enable (p. 13). The judgment bears directly on functional genus claims in biotechnology, antibodies in particular.

Facts and procedure

Antibodies can lower LDL cholesterol by inhibiting PCSK9, a protein that degrades LDL receptors (pp. 1 and 4). Amgen markets Repatha and Sanofi markets Praluent, each based on a distinct antibody described by its amino acid sequence in a 2011 patent not in issue (pp. 4 and 5). The dispute concerned claims 19 and 29 of the ‘165 patent and claim 7 of the ‘741 patent, obtained by Amgen in 2014, which cover the entire genus of antibodies binding to specified residues of PCSK9 (the « sweet spot ») and blocking it from binding to LDL receptors (pp. 1 and 5). Amgen identified the sequences of 26 antibodies and offered two methods for obtaining others: a screening « roadmap » and « conservative substitution » of amino acids in known antibodies, followed by testing (pp. 5 and 6). The district court granted Sanofi judgment as a matter of law, holding that the claims were not enabled, and the Court of Appeals for the Federal Circuit affirmed (pp. 6 and 7).

The applicable law

Section 112(a) of Title 35 of the United States Code requires the specification to describe the invention and the manner of making and using it in such full, clear, concise and exact terms as to enable any person skilled in the art to make and use it (pp. 2 and 8). The Court tied that requirement to the patent bargain, under which a limited monopoly is granted in exchange for a disclosure enabling the public to practise the invention (pp. 7 and 8), and to long-standing authority, namely O’Reilly v Morse, The Incandescent Lamp Patent and Holland Furniture v Perkins Glue, where claims broader than the disclosure were held invalid (pp. 9 to 13).

Question

Are claims defining a genus of antibodies by their function enabled where the specification discloses 26 examples together with screening and substitution methods for searching for others (p. 2)?

Decision

If a patent claims an entire class of processes, machines, manufactures or compositions of matter, its specification must enable a person skilled in the art to make and use the entire class (p. 13). That does not require every embodiment to be described: an example, or a few examples, may suffice where a general quality running through the class makes it fit for the purpose, and a specification may call for a reasonable amount of experimentation (pp. 13 to 15). Here the Court did not doubt that the specification enabled the 26 exemplary antibodies, but the claims extended to a « vast » number of further antibodies that were not described (pp. 15 and 16). The two methods offered amounted to little more than two research assignments, leaving the skilled person to proceed by trial and error, and were in effect a « hunting license » (pp. 16 and 17). The Court rejected Amgen’s arguments: there is one statutory enablement standard, which the Federal Circuit applied, recognising only that the more a party claims, the more it must enable (p. 18). Striking the balance between incentivising inventors and the public interest is a policy judgment for Congress (p. 19). The judgment was affirmed (p. 19).

Key points for practice

• A claim to an entire class must be enabled across its full scope; « the more one claims, the more one must enable » (p. 13).
• Representative examples and reasonable experimentation remain acceptable, in particular where a quality common to the class makes it fit for the purpose (pp. 13 to 15).
• Screening methods that amount to research assignments do not enable a genus defined by its function (pp. 16 and 17).
• Practical point: an antibody claim defined purely by function should be tested against the examples and general teaching of the specification; otherwise protection may be confined to the antibodies actually disclosed (pp. 15 to 17).

Provisions applied

National law

35 U.S.C. § 112(a) (United States)

Case law cited

Amgen Inc. v Sanofi, 987 F.3d 1080 (Fed. Cir. 2021) (decision under appeal); O’Reilly v Morse; The Incandescent Lamp Patent; Holland Furniture Co. v Perkins Glue Co.; Wood v Underhill; Minerals Separation v Hyde; Bonito Boats v Thunder Craft Boats; Continental Paper Bag Co. v Eastern Paper Bag Co.; Brenner v Manson; Grant v Raymond

Prepared by Dhenne Avocats from the text of the decision (US Supreme Court website, official slip opinion), consulted on 11 October 2026. Only the official text is authoritative.