## Facts

- High levels of low-density lipoprotein (LDL) cholesterol can cause serious health problems. A human protein, PCSK9, reduces the body’s ability to clear LDL cholesterol from the bloodstream by interfering with LDL receptors.
- Amgen developed a monoclonal antibody drug that binds to PCSK9 and blocks PCSK9 from binding to LDL receptors, which increases LDL receptor activity and lowers LDL cholesterol.
- In 2011, Amgen and Sanofi each obtained patents claiming specific PCSK9-targeting antibodies, described by their amino acid sequences.
- In 2014, Amgen obtained two additional patents that claimed a genus of antibodies defined primarily by function: antibodies that (1) bind to particular amino acid residues on PCSK9 and (2) block PCSK9 from binding to LDL receptors.
- The 2014 patent specifications disclosed the amino acid sequences of 26 antibodies that satisfied the binding-and-blocking requirements.
- The specifications also described two approaches for finding additional antibodies within the claimed genus:
  - A “roadmap” approach that instructed researchers to generate candidate antibodies and screen for those that bind to the specified PCSK9 residues and block PCSK9–LDL receptor binding.
  - A “conservative substitution” approach that suggested making amino-acid substitutions to known antibodies and then testing whether the modified antibodies still perform the claimed functions.
- Amgen sued Sanofi for patent infringement based on the 2014 genus patents. Sanofi responded that the asserted claims were invalid, including for failure to satisfy § 112(a)’s enablement requirement.
- The district court concluded that the asserted genus claims were not enabled and entered judgment for Sanofi. The Federal Circuit affirmed.
- The Supreme Court granted certiorari to address enablement for these functionally defined antibody genus claims.

## Issues

1. Whether, under 35 U.S.C. § 112(a), a patent claiming a genus defined by functional results must enable skilled artisans to make and use the full scope of the claimed genus without undue experimentation.
2. Whether Amgen’s disclosure of 26 antibodies plus screening-based methods for finding others enabled the full scope of the claimed antibodies—potentially numbering far beyond the disclosed examples.

## Decision

- The Supreme Court affirmed the Federal Circuit’s judgment that the asserted genus claims are invalid for lack of enablement under § 112(a).
- The Court held that when a patentee claims an entire class of compositions, the specification must enable a skilled person to make and use the entire class, allowing only a reasonable amount of experimentation.
- The Court concluded Amgen’s disclosure did not match the breadth of what it claimed: the patents taught how to make some antibodies (the 26 listed) but did not teach how to make and use the full range of antibodies that meet the functional claim limitations without substantial trial-and-error.
- The Court characterized Amgen’s “roadmap” and “conservative substitution” teachings as effectively instructing scientists to try candidates and see which ones work—more like assigning a research project than providing an enabling teaching for the whole claimed genus.

## Legal Principles

- Section 112(a) requires a patent to describe the invention “in such full, clear, concise, and exact terms” as to enable a person skilled in the art to make and use the invention.
- Enablement must be commensurate with claim scope: if a claim covers a class of compositions, the specification must enable the skilled artisan to make and use that class across its full scope.
- A patent may allow experimentation, but it may not require undue experimentation to practice the full scope of the claims.
- Functional claiming does not relax enablement. If claims are written to cover all compositions that achieve a stated result, the specification must teach how to obtain compositions across that result-defined range, not merely identify a few working examples and leave the rest to trial-and-error screening.
- Longstanding precedent rejects claims that seek exclusive rights over a broad result without teaching how to achieve it across the claimed range, including the Court’s older decisions involving the telegraph, electric lamp filaments, and starch glue formulations.
- The Court did not adopt a new enablement test; it applied the established principle that broader claims demand more complete enabling disclosure.

## Conclusion

The Supreme Court held that Amgen’s 2014 patents claimed a broad, function-defined genus of PCSK9-binding and PCSK9-blocking antibodies but did not enable skilled artisans to make and use the full scope of that genus without undue experimentation; disclosing 26 working antibodies and providing screening-and-testing instructions was insufficient, so the asserted claims were invalid under § 112(a).


Amgen, Inc. v. Sanofi, 598 U.S. 594, 143 S. Ct. 1243 (2023)