The U.S. Supreme Court, in a unanimous decision, has affirmed the Federal Circuit’s decision invalidating Amgen’s patent claims covering a genus of antibodies for failing to comply with the enablement requirement of the Patent Act.
Amgen’s Antibody Genus Claims
Repatha® (evolocumab) is Amgen's blockbuster biologic that is indicated for lowering bad cholesterol (low-density lipoprotein cholesterol) and reducing the risk of heart attack and stroke. Praluent® (alirocumab) is Sanofi’s and Regeneron’s competing biologic approved for the same indications. Both products bind to proprotein convertase subtilisin/kexin type 9 (PCSK9). These antibodies purportedly block PCSK9 from binding to low-density lipoprotein (LDL) receptors in order to prevent the mediation of LDL receptor degradation, and to allow LDL receptors to remove LDL cholesterol from the bloodstream. Amgen and Sanofi each have a patent specifically covering their respective biologic products.
Amgen also owns U.S. Patents 8,829,165 (the "'165 patent") and 8,859,741 (the "'741 patent"), which include the claims at issue covering a genus of antibodies that bind to amino acid residues of the PCSK9 protein, and block PCSK9 from binding to LDL receptors (specifically, claims 19 and 29 of the '165 patent and claim 7 of the '741 patent). The claims at issue thus relate to a class of antibodies based on their functions: 1) binding to specific amino acid residues on PCSK9 (referred to as an “epitope” claim limitation), and 2) blocking PCSK9 from binding to LDL receptors. Amgen identified the amino acid sequences of 26 antibodies that perform these two functions and depicted the three-dimensional structures of two of these 26 antibodies. In order to identify and make other antibodies that perform these two functions, Amgen offered scientists two methods. The first is what Amgen refers to as the “roadmap,” which directs scientists to generate antibodies and test whether the antibodies achieve the functional features recited in the claims. The second is what Amgen refers to as “conservative substitution,” which directs scientists to start with an antibody that has the claimed functional features, replace select amino acids in the antibody with other amino acids having similar properties, and test the resulting antibody to see if it also achieves the claimed functional features.
Amgen asserted the '165 patent and the '741 patent against Sanofi and Regeneron, alleging infringement by the competing product, Praluent. Sanofi and Regeneron contended that Amgen’s patents failed to meet the enablement requirement, and thus were invalid. Both the district court and the Federal Circuit agreed that the claims at issue lack enablement.
The Enablement Requirement Ensures That the Public Benefits from the Patent Bargain
The patent “bargain” describes the quid pro quo that incentivizes innovation by way of awarding time-limited exclusivity rights to the patent owner while also disseminating the innovation for public benefit and use upon expiration of the patent. Specifically, in order for the patent owner to obtain the benefit of an exclusive right to prevent others from commercializing a patented invention, the patent owner must enable those working in the field of the invention to "make and use" the patented claims.
The Supreme Court addressed this enablement requirement by referencing its own precedent cases such as O’Reilly v. Morse (1854), The Incandescent Lamp Patent (1895), and Holland Furniture Co. v. Perkins Glue Co. (1928), where patent claims overly broad in view of their accompanying disclosures were held invalid for lack of enablement so as not to “extend the monopoly beyond the invention” (quoting Holland Furniture).
The Court summarized these cases as “reinforc[ing] the simple statutory command” that
[i]f a patent claims an entire class of processes, machines, manufactures, or compositions of matter, the patent’s specification must enable a person skilled in the artto make and use the entire class.
In other words, the specification must enable the full scope of the invention as defined by its claims. The more one claims, the more one must enable
(emphasis added). However, the Court notes that specification need not “describe with particularity how to make and use every single embodiment within a claimed class” and “may call for a reasonable amount of experimentation to make and use a patented invention (emphasis added).”
With regard to description of the invention with particularity, citing Incandescent Lamp, the Court opines that “an example (or a few examples)” may suffice to support functional claim language “if the specification also discloses ‘some general quality … running through” the class that gives it “a peculiar fitness for the particle purpose.”
Amgen’s Antibody Genus Claims Lack Enablement over Their Full Scope
Applying the standard summarized from the Court’s precedent, the Court held that Amgen’s 26 disclosed antibodies, together with the roadmap and conservative substitution methods, were not sufficient to support the genus of antibodies claimed, “even allowing for a reasonable degree of experimentation.” The Court characterized the roadmap and conservative substitution methods as “little more than two research assignments” that force a scientist to “engage in painstaking experimentation” based on “trial and error” (internal quotations omitted). In affirming the Federal Circuit’s decision that the genus claims were not enabled, the Court did not directly address the long-established Federal Circuit test for enablement, which requires a person of skill in the art to practice the claimed invention without "undue experimentation" based on a number of factual considerations, termed the "Wands factors." Instead, the Supreme Court dismissed Amgen’s arguments that the Federal Circuit erred in its application of an enablement test, stating that both courts saw the same problem: “Amgen offers persons skilled in the art little more than advice to engage in ‘trial and error.’” Similarly, the Court disagreed with Amgen’s arguments that the Federal Circuit “raised the bar” for enablement of a class of embodiments defined by their function, stating that the Federal Circuit “recognized only that the more a party claims for itself the more it must enable.”
The Court cautioned that “enablement is not measured against the cumulative time and effort it takes to make every embodiment within a claim” and that there is no higher enablement bar for functionally-defined genera claims, but concluded that the Federal Circuit’s judgment turned on no such rule.
Patent Portfolio Strategies in View of Amgen
The underlying issue with the claims in Amgen, as well as those at issue in Morse, Incandescent Lamp, and Holland Furniture, was the breadth of the claims. In each case, the claims were broader than the invention sufficiently described. For instance, the Court found that the 26 antibodies of the class claimed by Amgen were enabled, just not the entire class of antibodies defined by their function.
This ruling will affect patent strategies for inventions related to platform technologies, as the claim breadth desired may not be sufficiently enabled by disclosure of a few proof-of-concept embodiments. Inventors will need to carefully balance the need to file on the invention early (increasing the likelihood of satisfying the novelty and nonobviousness requirements) with the need to provide sufficient description in the application to sufficiently enable the full claim scope desired.
For inventions that are claimed by functional properties, although the Court indicated that the enablement standard is not higher for these inventions, given the potential breadth of such claims, enablement is an important consideration for claim validity. Patents with functional claims should have adequate support in the specification for the structural features or other qualities in common to the functional embodiments claimed. As in the Amgen case, if a functional property of a claimed class can only be ascertained after elaborate experimentation or random trial-and-error testing, defining the invention by functional language alone may not suffice. If, however, there is a quality common to every functional property of the claimed class that provides a peculiar fitness for a specific purpose of the invention, that quality may sufficiently be enabled for the claimed class. In addition, patents with functional claim language should include claims that cover embodiments of the invention by shared structural features.
With specific regard to antibody inventions (as well as T cell receptor [TCR] and chimeric antigen receptor [CAR] inventions), claim strategies should be considered that are commensurate in scope with the antibodies described in the patent specification. In order to achieve broader claim scope, the application should disclose a variety of antibodies with shared features, perhaps dozens of antibodies or more, depending on the desired claim scope. These shared features can include structural features common among the disclosed antibodies, such as consensus complementarity determining region (CDR) sequences, specific CDR sequences, paratope residues (amino acids of the antibody that bind to the antigen), variable regions, antibody fragments, and antibodies having a certain sequence or structural identity to disclosed antibodies. For claims to a functional feature common among the antibodies, such as binding to a particular epitope, such functional feature may only satisfy the enablement requirement if the specification provides more guidance than in Amgen (that is, directing a skilled person to engage in a trial-and-error exercise). Although this may not be attainable for a U.S. patent, the requirements in ex-U.S. jurisdictions are not as onerous, and therefore epitope claims can still have a part in a company’s worldwide patent portfolio strategy.
We recommend that clients carefully consider patenting strategies for genus claims defined by functional properties, especially for claims related to antibody epitopes such as those at issue in Amgen and TCR epitopes. Importantly, any validity review of third-party patents in a freedom to operate analysis should take into consideration this ruling. For guidance on patent portfolio strategies, including analyses regarding freedom to operate, please contact a member of the firm’s patents and innovations practice.