Establishing Sufficiency and Infringement Standards in Second Medical Use Patents: Warner-Lambert v Generics (UK) Ltd [2018] UKSC 56

Introduction

The case of Warner-Lambert Company LLC v. Generics (UK) Ltd (t/a Mylan) & Anor ([2018] UKSC 56) is a landmark decision by the United Kingdom Supreme Court that addresses significant issues surrounding second medical use patents. Second medical use patents are crucial in the pharmaceutical industry as they incentivize the discovery of new therapeutic applications for existing compounds. However, these patents pose unique challenges within the traditional patent law framework, particularly concerning sufficiency of disclosure and infringement criteria.

In this case, Warner-Lambert, a subsidiary of Pfizer, held a European Patent (EP(UK) No 0934061) covering the use of pregabalin for treating pain, including specific types such as inflammatory and neuropathic pain. Generics (UK) Ltd and Actavis Group challenged the validity of this patent on the grounds of lack of inventive step and insufficiency, while Warner-Lambert alleged infringement of certain claims. The Supreme Court's judgment navigated complex legal territories, ultimately focusing on the sufficiency of disclosure in the patent specification and the appropriate test for infringement under a purpose-limited process claim.

Summary of the Judgment

The Supreme Court unanimously upheld the lower courts' decision that certain claims of the patent were invalid due to insufficiency of disclosure. Specifically, Claims 1 and 3, which broadly covered the use of pregabalin for treating all types of pain and neuropathic pain respectively, were found to lack adequate support in the patent specification for central neuropathic pain. The patent only sufficiently supported the efficacy of pregabalin in treating inflammatory and peripheral neuropathic pain, not central neuropathic pain.

Additionally, the Court addressed the contentious issue of infringement. It concluded that if the invalid claims had been valid, they would not have been infringed. The majority disagreed with the Court of Appeal's approach that involved an objective or subjective test based on the manufacturer's intention to market the drug for neuropathic pain. Instead, the Court favored an "outward presentation" test, which focuses on the characteristics and labeling of the manufactured product rather than the internal intentions of the manufacturer.

Consequently, the Supreme Court dismissed Warner-Lambert's appeal and allowed the cross-appeal by Actavis and Mylan, reinforcing the importance of precise disclosure in patents and clarifying the standards for infringement.

Analysis

Precedents Cited

The judgment extensively refers to precedents from both the United Kingdom and the European Patent Office (EPO) that have shaped the understanding of second medical use patents. Key among these are:

John Wyeth and Brother Ltd's Application [1985] RPC 545: Recognized Swiss-form patents despite initial skepticism, emphasizing uniformity under the EPC.
EISAI/Second Medical Indication G 05/83 [1979-85] EPOR B241: Established the legitimacy of Swiss-form patents by allowing claims directed at new therapeutic uses even when the manufacturing process remains unchanged.
SALK Institute for Biological Studies/AP-I complex (T 609/02): Refined the notion of sufficiency by requiring that a patent must provide a plausible basis for the claimed therapeutic effect, considering both experimental data and a priori reasoning.
Biogen Inc v Medeva Plc [1997] RPC 1: Introduced the concept of "Biogen insufficiency," where claims exceed the disclosed contribution to the art, rendering them insufficient regardless of their operability.

These precedents collectively underscore the necessity for patents, especially second medical use patents, to demonstrate a credible and plausible basis for their claims beyond mere assertion.

Legal Reasoning

The Supreme Court's reasoning pivots on two main legal questions: the sufficiency of disclosure in the patent specification and the appropriate test for infringement under a purpose-limited process claim.

Sufficiency of Disclosure: The Court emphasized the "patent bargain" wherein the inventor receives a monopoly in exchange for fully disclosing the invention. In the context of second medical use patents, simply referencing a known compound and asserting its efficacy for a new use is inadequate. The patent must provide a plausible reasoning or scientific basis that supports the claimed therapeutic effect. In this case, the specification adequately supported inflammatory and peripheral neuropathic pain but failed to do the same for central neuropathic pain, leading to the invalidation of those claims.

Infringement Test: The Court criticized both the subjective intention test and the objective foreseeability test adopted by the Court of Appeal. Instead, it endorsed an "outward presentation" test, focusing on the product's characteristics and labeling. This approach ensures that liability does not unjustly extend to downstream parties like pharmacists and users who cannot reasonably be expected to ascertain the manufacturer's internal intentions.

Moreover, the Court highlighted the policy objectives underpinning patent law: incentivizing innovation, ensuring public access post-patent, and providing legal certainty for third parties. These principles guided the Court in rejecting infringement tests that would either overly burden patentees or unduly restrict generic manufacturers.

Impact

This judgment has significant implications for the pharmaceutical sector and patent law:

Stricter Requirements for Sufficiency: Patent holders must ensure that their specifications provide a credible basis for all claimed uses, necessitating comprehensive scientific data or robust theoretical explanations.
Clarified Infringement Standards: The endorsement of the outward presentation test offers a clear, objective standard for assessing infringement, reducing uncertainty for third parties engaged in the distribution and use of generic drugs.
Consistency Across Jurisdictions: By aligning more closely with EPO and German precedents, the judgment promotes harmonization in the interpretation of second medical use patents within the UK, albeit differences remain across Europe.
Encouragement of Proper Labeling: Generic manufacturers are incentivized to maintain clear and accurate labeling to avoid infringement, balancing patent protection with freedom to operate.

Overall, the decision fosters a more balanced and predictable framework for second medical use patents, ensuring that innovation is rewarded without stifling generic competition.

Complex Concepts Simplified

Second Medical Use Patent: A patent granted for a new therapeutic application of an existing compound. It protects the specific use rather than the compound itself or the manufacturing process.

Sufficiency of Disclosure: A requirement that a patent application must provide enough detail for a skilled person to replicate the invention. For second medical use patents, this includes a credible basis for the new therapeutic use.

Infringement: Unauthorized use of a patented invention. For second medical use patents, infringement can occur if a product made using the patented process is used for the claimed therapeutic purpose.

Outward Presentation Test: An infringement test focusing on the characteristics, labeling, and presentation of the product, rather than the internal intentions of the manufacturer.

Swiss-form Patent: A form of patent claim used for second medical uses, allowing the use of a known compound in the manufacture of a medicament for a specific therapeutic application.

Biogen Insufficiency: A situation where a patent claim exceeds the technical contribution disclosed in the specification, making the claim invalid regardless of its operability.

Conclusion

The Supreme Court's decision in Warner-Lambert v Generics (UK) Ltd marks a pivotal moment in the landscape of second medical use patents. By reinforcing the necessity for sufficiency of disclosure and refining the standards for infringement, the Court has set a clear precedent that balances the interests of patent holders with the need for generic competition and public access. This judgment underscores the importance of meticulous patent drafting and strategic scientific substantiation, ensuring that patents serve their intended role of fostering genuine innovation without impeding subsequent advancements in medical therapeutics.