Post-Amgen Patent Playbook: Section 112 Under the Microscope

The Supreme Court’s unanimous 2023 decision in Amgen v. Sanofi, 598 U.S. 594 (2023), reshaped enablement analysis for broad genus claims under 35 U.S.C. §112. There, Amgen’s evolocumab (Repatha®) patents claimed a genus of antibodies that bind to specific amino acid residues of PCSK9 protein and block its activity, which helps lower LDL cholesterol. While the specification disclosed 26 examples, the claims sought to cover all antibodies with that function. The Court held that such broad claims require equally broad disclosure — “the more a party claims, the more it must enable.” The ruling confirms that functional genus claims must teach a POSA how to make and use substantially all embodiments without undue experimentation.
In the wake of Amgen, broad functional claims — especially ones covering potentially thousands or millions of undisclosed variants — have been scrutinized rigorously for sufficient disclosure. The Federal Circuit, in particular, has affirmed invalidity of several genus claims for lacking enablement or adequate written description support, while some patents have withstood these challenges where the disclosure was more tailored to the claim breadth. The courts have made a key distinction between a functional claim and structural ones, where less disclosure is required for structural claims. Below, we summarize key post-Amgen decisions, highlighting the written description and enablement issues, the courts’ analyses, and the implications for patent practice and would-be challengers. These cases illustrate how patent drafters and litigators must navigate the fine line between claim breadth and disclosure depth in the post-Amgen era.