Introduction

Case: FibroGen Inc v. Akebia Therapeutics Inc ([2021] EWCA Civ 1279)

Court: England and Wales Court of Appeal (Civil Division), Intellectual Property List, Patents Court

Date: 24th August 2021

This landmark case revolves around the validity and infringement of patents held by FibroGen Inc. and exclusively licensed to Astellas Pharma Inc., against Akebia Therapeutics Inc. and Otsuka Pharmaceutical Company Ltd. The patents in question pertain to the use of HIF-PH inhibitors for treating anemia associated with chronic kidney disease (CKD) and anemia of chronic disease (ACD). The court's decision has significant implications for patent claim sufficiency, especially concerning the combination of structural and functional features in chemical compounds.

Summary of the Judgment

Analysis

Precedents Cited

The judgment extensively referenced key patent law precedents, including:

• Regeneron v Genentech [2020] UKSC 27: Established a two-stage inquiry for assessing patent sufficiency, focusing on plausibility and undue burden.
• Biogen Inc. v Medeva plc [1977] R.P.C. 1: Clarified the scope of claim sufficiency in relation to general applications of an invention.
• Kirin-Amgen Inc v Hoechst Marion Roussel Ltd [2004] UKHL 46: Discussed the interplay between inventive step and sufficiency in patent claims.
• Conor v Angiotech [2008] UKHL 49: Highlighted that the technical contribution must align with the claim's scope and cannot be limited by partial findings of inventive step.
• Actavis v ICOS [2019] UKSC 15: Emphasized the importance of 'obvious to try' and 'reasonable prospect of success' in assessing inventive step and patent validity.

Legal Reasoning

The court's reasoning centered on the principles of patent claim sufficiency and inventive step, particularly in the context of chemical compounds defined by both structural and functional characteristics.

Family A Patents: Insufficiency

The Family A patents were challenged on the grounds of insufficiency, arguing that the claims were overly broad and lacked plausibility. The court adopted the two-stage approach from Regeneron v Genentech, assessing:

1. Plausibility: Whether the patent plausibly claimed that substantially all compounds within the structural framework would achieve the therapeutic effect.
2. Undue Burden: Whether the skilled person could perform the invention across the claim's scope without excessive effort.

Applying these, the court concluded that the patents were invalid. The claims were too broad, encompassing a vast number of compounds without sufficient evidence that they would all be efficacious, thereby failing both plausibility and undue burden tests.

Family B Patents: Obviousness

The Family B patents aimed to treat ACD using similar compounds. However, the court found these claims obvious over prior art (WO 997), as:

• WO 997 already suggested using HIF-PH inhibitors for various anemia-related conditions.
• The additional claims, focusing on specific patient TSAT levels or treatment-resistant anemia, were natural extensions of the prior art and did not involve an inventive step.

Consequently, the Family B patents were invalidated for obviousness.

Impact

This judgment sets important precedents in patent law, particularly concerning sufficiency and claim construction for chemical compounds:

• Enhanced Scrutiny on Sufficiency: Claims must be precise and supported by evidence across their entire scope, especially when combining structural and functional features.
• Undue Burden Re-Defined: The necessity for the skilled person to identify all or substantially all compounds is not required; however, claims should not impose excessive research burdens.
• Obviousness in Pharmaceutical Patents: Expands on the boundaries of what constitutes an inventive step, particularly in extending prior art applications.
• Claim Construction Clarity: Emphasizes clear definitions within patent claims to avoid ambiguity and ensure enforceability.

These principles will guide future patent applications and challenges, ensuring that claims are both innovative and sufficiently supported.

Complex Concepts Simplified

1. Patent Claim Sufficiency

Patent claim sufficiency requires that the invention is disclosed clearly and completely so that a skilled person can carry it out. It ensures that the patent does not grant monopolies over vague or overly broad claims that the inventor cannot adequately support.

2. HIF-PH Inhibitors

Hypoxia-inducible factor prolyl hydroxylase (HIF-PH) inhibitors are compounds used to stabilize HIF, which in turn can increase endogenous erythropoietin (epo) production. This process is beneficial in treating certain types of anemia.

3. Undue Burden

An undue burden in patent claims refers to a requirement that the invention can be practiced without excessive effort. If fulfilling the claim demands an impractical amount of work, the patent claim may be invalidated for placing an undue burden on those seeking to use the invention.

4. Obviousness

Obviousness assesses whether an invention is sufficiently inventive or if it merely extends existing knowledge in an obvious way. If a claimed invention would be obvious to a person skilled in the field, the patent may be invalidated for lacking an inventive step.

5. Formula I

Formula I refers to a specific chemical structure defined within the patent. Determining whether a compound like vadadustat falls within Formula I involves analyzing its molecular structure against the formula's defined parameters.

Conclusion

The Court of Appeal's decision in FibroGen Inc v. Akebia Therapeutics Inc significantly clarifies the standards for patent claim sufficiency and inventive step, especially for chemical compounds defined by both structural and functional features. By invalidating the Family A patents for insufficiency and the Family B patents for obviousness, the court underscored the necessity for clear, evidence-backed, and narrowly tailored patent claims. This ruling not only influences future patent applications in the pharmaceutical sector but also reinforces the judiciary's role in maintaining a balance between innovation incentives and preventing monopolies over inadequately described inventions.