Amgen v. Sanofi – Federal Circuit Focuses on Functional Claim Elements in Affirming Invalidity of Antibody Patent Claims as Not Enabled

Recently, the Federal Circuit affirmed the decision of the U.S. District Court for the District of Delaware holding claims covering two Amgen-owned patents invalid for lack of enablement under 35 U.S.C. § 112.  Amgen Inc., v. Sanofi, 2021 U.S. App. LEXIS 3952 (Fed. Cir. 2021).  The patents at issue are directed to antibodies that bind to the PCSK9 protein, and cover the antibody, evolocumab (Repatha®).

The Federal Circuit applied the Wands factors—another case that happened to involve antibody technology—to aid in determining whether the amount of experimentation needed to practice the full scope of the claims is “undue”.  The Federal Circuit reviewed recent caselaw regarding the enablement inquiry for claims that include functional requirements, and noted that such an inquiry “can be particularly focused on the breadth of those requirements, especially where predictability and guidance fall short.”  The Federal Circuit further stated [i]n particular, it is important to consider the quantity of experimentation that would be required to make and use, not only the limited number of embodiments that the patent discloses, but also the full scope of the claim.”  The Federal Circuit noted that “such [functional] limitations pose high hurdles in fulfilling the enablement requirement for claims with broad functional language.”

The Federal Circuit found that the breadth of the claims lied not only in the number of possible embodiments, but that the claims were also “far broader in functional diversity than the disclosed examples.”  The specification disclosed only a few embodiments that were structurally representative of the claims.  The Federal Circuit also found that the invention was in an unpredictable field of science, a finding supported by admissions of several of Amgen’s experts.  The Federal Circuit noted that “the only ways for a person of ordinary skill to discover the undisclosed embodiments would be through either ’trial and error’ . . . or else ‘by discovering the antibodies de novo’”, and that either method of experimentation way would require a substantial amount of time and effort to reach the full scope of the claimed embodiments.  The Federal Circuit thus concluded that such experimentation would be undue.

While there continues to be uncertainty regarding what amount of experimentation is undue for purposes for finding lack of enablement, this case provides a clear signpost from the Federal Circuit that patent claims having functional limitations must meet a higher bar to show enablement, and as such are more susceptible to invalidity challenges for lack of enablement, particularly if they lack  supporting disclosure that provides an array of embodiments covering the breadth of the claims.