In 2021, the Federal Circuit determined that Amgen’s biotech antibody patents lack enablement, i.e., the specification did not teach one of ordinary skill in the art how to make and use the invention without undue experimentation. Amgen Inc. v. Sanofi, 987 F.3d 1080 (Fed. Cir. 2021). Specifically, the Federal Circuit held that undue experimentation would be required to practice the “full scope” of the claims. The Federal Circuit denied rehearing en banc of this decision.

The Amgen patents at issue cover a cholesterol medication, Evolocumab, marketed as Repatha®, a PCSK9 inhibitor used to lower LDL levels. Evolocumab is a monoclonal antibody with high specificity and affinity for binding to the PCSK9 protein. By binding to PCSK9, the drug blocks PCSK9 from binding to LDL receptors. LDL receptors are thus left free to extract LDL from the bloodstream. Monoclonal antibodies have extremely complex three-dimensional structures highly sensitive to the manufacture process. The composition claims at issue have functional limitations – they define the compound not based on their structure, but based on their function, specifically the affinity for binding to certain amino acid sequences of PCSK9. As such, there is a broad group (a genus) of compounds that fall within the claim.

The Supreme Court granted Amgen’s petition for certiorari on the single issue of whether enablement is governed by the statutory requirement that the specification teach those skilled in the art to “make and use” the invention (35 U.S.C. § 112), or whether it must enable the “full scope of the functional limitations” without undue experimentation by identifying and making all or nearly all embodiments of the invention. Amgen Inc. v. Sanofi, No. 21-757, 2022 U.S. LEXIS 4836, at *1 (Nov. 4, 2022).

Amgen argues that the “full scope” standard employed by the Federal Circuit imposes a heightened, impossible burden to satisfy — to show which of the millions of species within the functional genus satisfy the claim limitations. Amgen makes a distinction between the experimentation needed on cumulative embodiments, i.e., the amount of time and effort it would take to make and use all claimed embodiments, as opposed to making and using any individual embodiment, which would not require undue experimentation.

Sanofi markets a competitor PCSK9 inhibitor drug, Praluent® (alirocumab). Sanofi argues that the Federal Circuit applied well-established law after a case-specific weighing of the Wand factors (In re Wands, 858 F.2d 731 (Fed. Cir. 1988)), including breadth of claims.

At stake is the future of many biotech patents. If innovators are only able to obtain patent protection on individual species or a small genus, they may not be able to obtain sufficiently robust patent protection to prevent competitors from copying their invention. While the Federal Circuit stated the enablement requirement does not preclude functional claims, the decision seems to raise substantial barriers to such claims for antibodies and other biotech and pharmaceutical inventions.

For more information, please reach out to Harris Beach Attorney Marina Plotkin at (212) 313-5409 or, or to Harris Beach Attorney Laura W. Smalley at (585) 419-8736 or

This alert is not a substitute for advice of counsel on specific legal issues.

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