Introduction

The case of FibroGen Inc v. Akebia Therapeutics Inc ([2021] EWCA Civ 1279) delves into complex issues surrounding patent validity, specifically focusing on sufficiency of disclosure and obviousness in pharmaceutical patents. The dispute involves six patents owned by FibroGen, exclusively licensed to Astellas, which relate to the use of HIF-PH inhibitors for treating anemia, including Chronic Kidney Disease (CKD) anemia and Anemia of Chronic Disease (ACD).

Parties Involved:

• Appellants: FibroGen Inc and Astellas Pharma Inc
• Respondents: Akebia Therapeutics Inc and Otsuka Pharmaceutical Company Ltd

The central legal questions revolved around the validity of the patents based on grounds of insufficiency (lack of plausibility and undue burden) and obviousness over prior art (specifically WO 997). The Court of Appeal's judgment provides pivotal insights into how broad patent claims, especially those defined by both structural and functional features, are scrutinized under current jurisprudence.

Summary of the Judgment

The Court of Appeal upheld the lower court's decision to invalidate the Family A patents on the grounds of insufficiency, finding that the patents lacked plausibility and that the breadth of the claims imposed an undue burden on those skilled in the art. Specifically, the court determined that it was not plausible that substantially all compounds falling within the structural definitions of the patents would possess the claimed therapeutic efficacy. Furthermore, executing the invention across the entire scope of the claims would require an impractical amount of research, rendering the patents invalid.

Regarding the Family B patents, which pertain to the treatment of ACD, the court found them obvious over the prior art WO 997. The prior art already suggested using HIF-PH inhibitors for treating related conditions, making the claims lack inventive step. Additionally, the Family B patents were also deemed insufficient for similar reasons as Family A.

The appeal by FibroGen challenged these findings, particularly disputing the conclusions on insufficiency and arguing inconsistencies regarding infringement findings. However, the Court of Appeal dismissed the appeal, maintaining the invalidation of the patents based on robust legal reasoning.

Analysis

Precedents Cited

The judgment extensively referenced these precedents to navigate the nuanced landscape of patent law, particularly focusing on the sufficiency of disclosure and the inventive step. These cases collectively influence how broad claims, especially those incorporating functional features, are interpreted and validated.

Legal Reasoning

The Court of Appeal employed a meticulous approach to dissecting the patent claims under scrutiny. The primary legal framework utilized was the two-stage inquiry established in Regeneron v. Genentech:

1. Plausibility: The court examined whether it was plausible that the compounds claimed would have the therapeutic effects across their entire scope. It concluded that the patents did not make a reasonable prediction that substantially all compounds within the structural definitions would possess the claimed efficacy.
2. Undue Burden: Beyond plausibility, the court assessed whether practicing the invention across the claim's breadth would impose an undue burden on those skilled in the art. Given the vast number of potential compounds covered by the claims, the court found that identifying and validating each compound's efficacy was impractical, further invalidating the patents.

For the Family B patents, the court applied the concept of obviousness, determining that the use of HIF-PH inhibitors for treating ACD was an obvious extension of the teachings in prior art WO 997. The absence of inventive step, combined with insufficiency, cemented the invalidation of these patents.

Impact

This judgment has significant ramifications for the pharmaceutical industry and patent law, particularly in the realm of broad claims defined by both structural and functional features. Key impacts include:

• Stricter Standards for Sufficiency: Patents with broad claims must demonstrate plausibility that the invention works across its entire scope or risk being invalidated for insufficiency.
• Caution Against Overly Broad Claims: Innovators are advised to narrowly define their claims or provide sufficient evidence supporting the efficacy of all claimed compounds to avoid undue burden.
• Clear Distinction Between Structural and Functional Features: The court emphasized the necessity of clearly linking functional features to structural components to ensure claims are neither overly broad nor insufficiently disclosed.
• Reaffirmation of Obviousness Standards: The decision upholds the principle that extensions of existing teachings, without an inventive step, do not warrant patent protection.

Future patent applications in similar fields will likely see more rigorous scrutiny regarding the relationship between claim breadth, sufficiency, and inventive step, encouraging more precise and evidence-backed claims.

Complex Concepts Simplified

Conclusion

The FibroGen Inc v. Akebia Therapeutics Inc judgment serves as a critical reminder of the delicate balance in patent law between protecting genuine innovations and preventing overly broad claims that hinder further research and development. By invalidating patents for insufficiency and obviousness, the Court of Appeal reinforced that patents must be both sufficiently disclosed and non-obvious in their claims.

For practitioners and entities in the pharmaceutical sector, this case underscores the necessity of precise claim drafting and the importance of robust evidence supporting the efficacy of claimed compounds. It also highlights the judicial willingness to scrutinize broad functional claims, ensuring that patents contribute meaningfully to technological advancement without stifling innovation.

Overall, this judgment contributes significantly to the evolving landscape of patent law, particularly in the context of complex chemical and pharmaceutical inventions, setting a precedent for future cases to ensure clarity, precision, and practical applicability in patent claims.