Amgen Inc. v. Sanofi

Amgen Inc. v. Sanofi was a patent dispute over two Amgen patents covering PCSK9 inhibitor antibodies used to lower LDL cholesterol. Amgen sued Sanofi and Regeneron for infringement after they developed a competing antibody drug, Praluent. The patents claimed an entire genus of antibodies defined by their function—binding to specific PCSK9 residues and blocking the PCSK9/LDLR interaction—but the specification disclosed only 26 antibody structures by amino acid sequence. The U.S. Supreme Court, in a unanimous opinion authored by Justice Gorsuch, held that the claims were invalid for lack of enablement under 35 U.S.C. §112(a), as the specification failed to teach skilled artisans how to make and use the full scope of the claimed genus without undue experimentation. The decision affirmed the Federal Circuit and resolved a split, clarifying that broad functional claims in biotechnology require commensurate structural guidance.

The U.S. Supreme Court unanimously affirmed the Federal Circuit, holding that Amgen's two patent claims were invalid for lack of enablement. The Court ruled that the specification did not enable a person skilled in the art to make and use the full claimed genus of antibodies, because the functional definition covered potentially millions of undisclosed antibodies and the patent provided insufficient structural or methodological guidance, requiring undue experimentation.

Whether Amgen's patent claims, which covered an entire functional genus of PCSK9 antibodies, satisfied the enablement requirement of 35 U.S.C. §112(a) even though the specification identified only a limited number of working antibody examples and did not provide a general method for making other antibodies within the claimed scope.

The decision tightened the enablement standard for broad functional patent claims in biotechnology and pharmaceuticals. It is expected to encourage more detailed structural disclosures in antibody and biologic patents, limit overly broad genus claims, and influence patent prosecution strategies. The ruling may also affect incentives for drug innovation and competition by reducing the ability of originator companies to block follow-on biologics with sweeping functional claims.