Navigating Claim Scope For Functionally Claimed Biological Compounds After Amgen v. Sanofi

By Jonathan B. (J.B.) Fitzgerald, Ph.D., Snell & Wilmer L.L.P.

Patentees often want claims that are broad in scope in order to capture as many variations as possible of their invention. However, because the biological arts are treated as an unpredictable art in the field of patents, it is often challenging to obtain and defend patent claims directed to biological compounds that have broad scope. In particular, it can be difficult for broad biological compound claims to meet the two requirements in patent law that are used to “police” claim scope. These requirements are known as the enablement requirement and the written description requirement. Both requirements must be met for any claim (including a claim covering a biological composition) to be valid and enforceable.

The general test that must be satisfied under the enablement requirement is that the patent must provide enough description such that a person skilled in the field could make and use the claimed invention, without undue experimentation. The general test that must be satisfied for the written description requirement is whether the inventor(s) provided sufficient description in the patent to show that there was “possession” of the claimed invention at the time of filing.  Thus, for a biological composition claim, the patent must show both (i) that a person skilled in the field of biology (e.g., a biologist) can make and use the claimed biological composition, without having to engage in excessive experimentation and (ii) that there is sufficient description of the biological composition in the patent to prove that the inventor(s) was in possession of the biological composition at the time of filing the patent.

Because functionally claimed biological compounds are often broader in scope than structurally claimed biological compounds, patentees often claim biological compounds according to their functional properties. So, for example, an invention covering synthetic antibodies might be claimed according to their function of binding a specific antigen, rather than claiming the antibodies according to their structure of amino acid sequences. Claiming biological compounds according to their functional properties often results in a broad ”genus” claim, which encompasses all of the species of the biological compounds capable of carrying out the claimed functional properties.

However, it can be difficult to prove that a broad functional genus of biological compounds (i) can be made and used without undue experimentation (i.e., satisfying the enablement requirement) and (ii) are sufficiently described to show possession (i.e., satisfying the written description requirement). Evidence of this difficulty is shown in two recent Federal Circuit cases, Amgen v. Sanofi¹ (Amgen) and Juno v Kite² (Juno). In the Amgen case, the Federal Circuit invalidated claims directed to antibodies that were defined by their functional ability, finding that the claimed antibodies failed to meet the enablement requirement. In the Juno case, the Federal Circuit invalidated claims directed to nucleic acids that encoded receptors containing a functionally defined binding element, finding that the claimed nucleic acids failed to meet the written description requirement. Thus, the Amgen case and the Juno case represent two separate cases in which genera of functionally claimed biological compounds were invalidated for failing to meet the enablement and written description requirements, respectively.

Both the Amgen case and the Juno case were appealed to the Supreme Court. On Nov. 4, 2022, the Supreme Court agreed to review the application of the enablement requirement to biological composition claims containing functional limitations.³ However, on Nov. 7, 2022, the Supreme Court declined to review the application of the written description requirement to biological composition claims containing functional limitations.⁴ On Jan. 9, 2023, a petition for rehearing of the Juno case was denied by the Supreme Court.

Thus, the Supreme Court decided to review only one of the standards, the enablement standard, that is used to police claim scope of functionally claimed biological compounds. Since both the enablement and written description standards relate to policing claim scope, the Supreme Court’s decision to review only the enablement standard will likely impact how claim scope for functionally claimed biological compounds will be policed in the future.

This article will examine this potential impact through:

1. describing the enablement test used by the Federal Circuit in the Amgen case for analyzing functionally claimed biological compositions;
2. discussing the nature of the Supreme Court’s review of the Federal Circuit’s enablement test;
3. describing the Federal Circuit’s written description standard in Juno for analyzing functionally claimed biological compositions;
4. discussing overlap between Amgen’s enablement analysis and Juno’s written description analysis; and
5. forecasting the potential impact on policing claim scope of functionally claimed biological compounds, after the Supreme Court’s ruling in the Amgen case.

The “Full Scope” Enablement Test In Amgen v. Sanofi

The claims at issue in Amgen are directed to monoclonal antibodies defined by their dual functional abilities to both (i) bind specific amino acid residues on an enzyme and (ii) block binding of that enzyme to a receptor. The Federal Circuit determined that these dual function antibodies failed to meet the enablement requirement.

In the Amgen case, the Federal Circuit made clear that to satisfy the enablement for functionally claimed compounds, a person of skill must be able to practice the full scope of the claim without undue experimentation. Specifically, the Federal Circuit stated that the enablement test for claims that include functional requirements should be “focused on the breadth of those requirements…In 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.”

Thus, in Amgen, the Federal Circuit applied what can be characterized as a “full scope” enablement test to biological composition claims containing functional limitations. Under this full scope test, all of the variations (species) of the biological compounds covered by the claims must be analyzed to determine whether undue experimentation would be required.  

When it applied this full scope test to the claims at issue, the Federal Court concluded that the claims were invalid under the enablement requirement. According to the Federal Circuit, the experimental burden of screening antibodies to identify those with the dual function of binding specific amino acids on an enzyme and preventing that enzyme from binding a receptor was too high. As a result, undue experimentation would have been required to make and use the full scope of all the antibodies covered under the claims.

The Supreme Court’s Review Of The Full Scope Test

On Nov. 4, 2022, the Supreme Court agreed to review the validity of the Federal Circuit’s full scope enablement test. Specifically, the Supreme Court will review whether meeting the enablement standard for functionally claimed compounds (i) requires enabling the full scope of the compounds (i.e., enabling all of the variations of compounds that are covered under the claims) or (ii) requires only enabling a subset of the variations (or even a single variation) of compounds covered the claims.

Thus, in Amgen, the Supreme Court is ultimately deciding on the strictness of the enablement requirement. Will the Supreme Court agree with the Federal Circuit and conclude that the full scope of the claims must be enabled? Or, will the Supreme Court decide that a less stringent enablement standard is proper in which only a select number of variations (or a single variation) covered by the claims must be enabled?

The Supreme Court’s ruling in Amgen is expected sometime in the spring or summer of 2023.

The Federal Circuit’s Written Description Analysis Of Functional Limitations In Juno v. Kite

The claims at issue in Juno were directed to nucleic acid polymers that encode chimeric T receptors containing a single-chain variable fragment (scFv), which is a protein that contains antibody regions capable of binding to targets. Notably, the scFvs were claimed according to their function of being able to bind to a selected target. The Federal Circuit determined that the functionally defined scFvs failed to meet the written description requirement.  

To satisfy the written description requirement, the inventor(s) needs to provide sufficient description in the patent to prove that the inventor(s) was in possession of the claimed invention when the patent was filed. Because the scFvs were claimed according to their functional ability to bind a selected target, the claims covered a genus of functionally defined scFvs. Possession of a genus can be shown by either (i) describing a representative number of species in the genus or (ii) describing the structural features that are common to the genus.

In its analysis of the genus of the functionally claimed scFvs, the Federal Circuit concluded that neither (i) nor (ii) were satisfied, and, therefore, it invalidated the claims under the written description requirement.  Specifically, the Federal Circuit decided that the two variations (species) of scFvs disclosed in the patent that were capable of carrying out the binding function were insufficient to show a representative number of species. In addition, the Federal Circuit found that there was a failure in the patent to describe structural features common to the genus of scFvs capable of carrying out the binding function. Because of these deficiencies, the Federal Circuit concluded that the inventors failed to demonstrate that they “possessed the entire class of possible scFvs that bind to the various selected targets.” Thus, the Federal Circuit concluded that the patent “provides nothing to indicate that the inventors possessed the full scope of the genus that they chose to claim.” (emphasis added)

Overlap Between Amgen’s Full Scope Enablement Test And Juno’s Written Description Analysis

In the Amgen case, the full scope enablement test for functionally claimed biological compounds requires that all of the variations (species) of compounds are enabled. In Juno, in order for functionally claimed biological compounds to satisfy the written description standard, the patent must show that the inventor(s) possessed all of the variations (species) of the compounds. Thus, in its application of both the enablement test in Amgen and written description test in Juno, the Federal Circuit emphasized the importance of either enabling or possessing the full scope of the claimed subject matter.  

The Future Of Policing Claim Scope For Functionally Claimed Compositions After Amgen v. Sanofi

It is possible that in its upcoming ruling in Amgen, the Supreme Court could find that the full scope enablement test is improper and overrule it. This would result in upholding a less stringent enablement standard in which only a subset of variations or species (or a single variation or species) of a functionally claimed biological compound would need to be enabled. However, because the Supreme Court declined to review the written description standard for functional claimed biological compounds, this standard will remain intact. 

Thus, regardless of the Supreme Court’s ruling in Amgen, a defendant that is accused of infringing a functionally claimed biological composition will still have the defense available of alleging that the patentee overreached in its claims by failing to show possession of the entire species of functionally claimed compounds that are covered by the claims. As the Federal Circuit stated in the Juno case, “To satisfy written description…the inventors needed to convey that they possessed the claimed invention, which encompasses all scFvs, known and unknown…that bind to a selected target.” This written description standard will continue to provide patent litigant defendants with a powerful tool to argue that functionally claimed biological compounds should be invalidated and, thus, unenforceable because the inventor(s) failed to possess the full scope of those compounds.

If the Supreme Court decides to uphold the full scope enablement test set forth in Amgen, it will uphold a strict standard that requires patentees to enable all (or virtually all) of the claimed embodiments. However, even if the Supreme Court overturns the full scope test, the standard under the written description requirement of possession of the full scope of the claims will remain intact. Thus, the real issue at stake in Amgen may be whether claim scope for functionally claimed biological compounds will be policed by one strict standard requiring showing possession of the full scope of the claims or by two strict standards requiring both showing possession of and enabling the full scope of the claims.

References

1. Amgen Inc. v. Sanofi, No. 2020-1074 (Fed. Cir. 2021).
2. Juno Therapeutics, Inc. v. Kite Pharma, Inc., No. 2020-1758 (Fed. Cir. 2021).
3. Amgen Inc. v. Sanofi, No. 21-757 (U.S. Nov. 4, 2022).
4. Juno Therapeutics, Inc. v. Kite Pharma, Inc., No. 21-1566 (U.S. Nov. 7, 2022).

About The Author:

Jonathan B. (J.B.) Fitzgerald, Ph.D., is counsel at Snell & Wilmer. He is a registered patent attorney and has a Ph.D. in molecular physiology. His primary practice area involves preparing and prosecuting patent applications in the biotechnology and the life sciences.