Functional Claiming of Broad Genus Potentially Including Millions of Antibodies Rejected by U.S. Supreme Court
On May 18, 2023, in Amgen Inc. v. Sanofi[1] the U.S. Supreme Court affirmed the invalidity of two Amgen patents claiming antibodies. In its the unanimous 9-0 decision, penned by Justice Gorsuch, the Court held that the Amgen patents did not fully enable the multitude of antibodies of a claimed genus that was described functionally.
Amgen initially obtained a patent for antibodies that bind to amino acids on the PCSK9 protein inhibiting its function. PCSK9 contributes to high cholesterol levels by binding to LDL receptors. The Amgen patent described some antibodies by their unique amino acid sequence in the specification. Sanofi, a competitor of Amgen, also patented a PCSK9-inhibiting antibody with a different sequence from that disclosed by Amgen.
Subsequently, Amgen obtained patents not tied to a particular antibody structure or amino acid sequence, but to an entire genus of antibodies that bind to specific amino acid residues on PCSK9. Amgen identified 26 exemplary antibodies by their amino acid sequences, yet claimed the antibodies by what they do, not by what they are. Amgen sued Sanofi for infringement and Sanofi argued that the broad claims were not fully enabled.
Although juries twice concluded that the patents were not invalid due to lack of enablement, in a second trial, the district court granted Sanofi's motion for judgment of invalidity as a matter of law. The district court concluded that the full scope of the claims of Amgen’s patents was not enabled. The Court of Appeals for the Federal Circuit (CAFC) agreed with the district court that Amgen failed to meet the enablement requirement as a matter of law, even with reasonable degree of experimentation.
The enablement requirement contained in the Patent Statute at 35 U.S.C. Sec. 112(a) requires that the patent specification must set forth a description of the invention that would enable those of skill in the art to make and use the invention. The enablement requirement is satisfied if those of ordinary skill in the art would be able to practice the full scope of the invention without undue experimentation.
The amount of "undue experimentation" required involves factual considerations, known as the “Wands factors.” Interestingly, the Wands factors are derived from a biotechnology case also involving monoclonal antibody production and medical diagnostics. The Wands factors to be considered include the breadth of the claims, the amount of direction presented by the inventor, the existence of working examples, and the quantity of experimentation needed.
Amgen argued that the broad claims are enabled because “scientists can make and use every undisclosed but functional antibody if they simply follow the company’s ‘roadmap’ or its proposal for ‘conservative substitution.’”
The Court disagreed and reasoned that the roadmap instructions were insufficient “research assignments” rather than a clear procedure for making the additional antibodies that were functionally claimed. The Court further reasoned that these particular disclosures were not enabling as they only describe a trial-and-error method that Amgen had used. The given method did not provide enough instruction for those skilled in the art to make and use the entire genus of claimed antibodies.
For its part, Sanofi conceded that the description allows a person skilled in the art to make and use the 26 exemplary antibody embodiments listed in the Amgen patent and explicitly identified by their amino acid sequences. However, the Court stated that “the claims before us sweep much broader than those 26 antibodies,” and thus, Amgen failed to fully enable all that it claimed, even after accounting for a reasonable degree of experimentation.
The Court also reiterated a “simple statutory command” that “if 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 art to make and use the entire class.” Simply stated, the full scope of the invention as defined by its claims must be enabled.
The Court also confirmed that a specification is not inadequate if it leaves the skilled artist to engage in reasonable experimentation to make and use a patented invention. The Court clarified that what is “reasonable” experimentation depends on the nature of the invention and the underlying art.
Amgen argued that functional or genus claims should not be held to a stricter standard of enablement because the Patent Act supplies a single universal enablement standard, while the CAFC applied a higher standard to Amgen’s claims that encompass an entire genus of embodiments defined by their function. The Court only partially agreed with Amgen’s position, explaining that there is only “one statutory enablement standard; however, broader claims necessitate more enablement. This is because ‘the more a party claims, the broader the monopoly it demands, the more it must enable.” Indeed, this is the cornerstone of the patent bargain.
The Supreme Court’s decision does not change the law of enablement. However, it may make broad functionally defined genus claims more vulnerable to enablement challenges. The decision will likely pose an impediment in obtaining patents that broadly claim an entire genus defined by a specific function. This is especially true in the life sciences such as immunology, biology, and pharmacology where such patents are often pursued. Consequently, patent prosecutors and litigators will have to adapt and consider additional questions and issues.
First, a specification should provide substantial guidance when describing and selecting embodiments. Patent practitioners should pay particular attention to the Wands factors when drafting patents, especially in the life sciences.
Second, subgenus and species claims should be included in case broader genus claims are invalidated. The practice of using a few examples to enable millions of potential variants seems obsolete. Thus, patent practitioners may now claim less broadly, and inventors conduct and disclose far more experiments to enable broad patent claims. However, it is impractical to reduce to practice every possible applicable species. This may be particularly challenging for pharmaceutical companies because of the substantial expenses associated with drug development. Such companies rely on the exclusivity afforded by their patents to recoup their investments.
In litigation, enablement challenges for broad functional genus claims may increase in frequency. Patent litigators will likely develop novel strategies and gather necessary evidence early in the discovery phase to address issues that will arise in such challenges.
This decision illustrates the delicate balance the Court has to strike between the patent system’s policies of supporting innovation by permitting companies to prevent others from copying their invention, while also preventing monopolies that stifle innovations. However, Congress considered these issues when drafting the patent statutes; thus, “the Court’s duty is to enforce the statutory enablement requirement according to its terms.”
