Warner-Lambert Company LLC v Generics (UK) Ltd (t/a Mylan) & Anor [2018] UKSC 56

Warner-Lambert held a Swiss-form patent for pregabalin to treat pain, including neuropathic pain. Generic manufacturers Mylan and Actavis sought revocation. The Supreme Court held the patent insufficient regarding neuropathic pain claims and, even if valid, would not have been infringed.

Facts

Warner-Lambert, part of the Pfizer Group, held European Patent EP(UK) No 0934061 for the use of pregabalin (marketed as Lyrica) in the preparation of a pharmaceutical composition for treating pain, including inflammatory pain (Claim 2) and neuropathic pain (Claim 3). The patent was a Swiss-form, purpose-limited process patent. Generics (UK) Ltd (Mylan) and Actavis marketed a generic pregabalin product (Lecaent) under a ‘skinny label’ authorised only for epilepsy and generalised anxiety disorder, indications for which patent protection had expired.

Mylan and Actavis sought revocation of the patent for lack of inventive step and insufficiency. Warner-Lambert counterclaimed for infringement. Arnold J held that Claims 1 (all pain) and 3 (all neuropathic pain) were invalid for insufficiency, finding sufficient disclosure only for inflammatory pain and peripheral neuropathic pain, but not central neuropathic pain. The Court of Appeal upheld this conclusion but differed from the judge on the proper test for infringement.

Issues

• Construction of Claim 3: whether ‘neuropathic pain’ encompassed all neuropathic pain, including central neuropathic pain, or only peripheral.
• Sufficiency: whether the specification supported the claims, applying the plausibility test for second medical use patents.
• Whether Arnold J was right to refuse a post-judgment amendment as an abuse of process.
• The correct test for infringement of a Swiss-form purpose-limited process patent under section 60(1)(c) and indirect infringement under section 60(2) of the Patents Act 1977.

Arguments

Warner-Lambert

Argued Claim 3 should be construed narrowly as limited to peripheral neuropathic pain. On sufficiency, contended that the plausibility threshold was either inapplicable or very low, and that later published clinical data could establish efficacy. On infringement, argued for a foreseeability test: a manufacturer infringes where it is foreseeable that more than de minimis quantities would be used for the patented indication.

Actavis and Mylan

Contended Claim 3 covered all neuropathic pain and that the specification failed to make therapeutic efficacy plausible across that scope. On infringement, argued that the test was the manufacturer’s subjective intention to target the patent-protected market, alternatively that the test depended on the outward presentation of the product.

Judgment

Construction

The Court unanimously held that Claim 3 extended to all neuropathic pain, including central neuropathic pain. The descriptions in paragraphs 3 and 6 of the patent used inclusive language and the claims descended from broad to narrow categories. The validating principle of construction had a diminished role in modern patent law given the Protocol on the Interpretation of Article 69 EPC, which requires a balance between fair protection and legal certainty.

Sufficiency and Plausibility

By a majority (Lord Sumption, Lord Reed and Lord Briggs), the Court held that the specification supported claims for inflammatory pain but not for any neuropathic pain. The plausibility test, derived from EPO jurisprudence (notably SALK, ALLERGAN, IPSEN and BRISTOL MYERS SQUIBB), requires the patentee to disclose some scientific reason supporting the claimed therapeutic effect. The animal models disclosed (rat paw formalin test, carrageenin test, post-operative pain model) predicted efficacy only for inflammatory pain. The trial judge’s finding that central sensitisation was ‘involved’ in both inflammatory and peripheral neuropathic pain did not establish a unifying mechanism justifying extrapolation to neuropathic pain. Lord Mance and Lord Hodge dissented, considering the threshold lower and that Arnold J’s finding of plausibility for peripheral neuropathic pain should stand.

Amendment and Abuse of Process

The Court unanimously upheld Arnold J’s refusal to permit Warner-Lambert’s post-judgment application to amend the patent. Following Nikken and Nokia v IPCom, post-trial amendments requiring a further trial were prima facie abusive. Article 138(3) EPC required contracting states to provide a power of amendment but did not override national procedural law.

Infringement

The Court held unanimously that the indirect infringement claim under section 60(2) failed: the invention protected by Claim 3 was the manufacture of pregabalin for the designated use, not subsequent dispensing or use. On direct infringement under section 60(1)(c), the Court divided. Lord Sumption and Lord Reed favoured an ‘outward presentation’ test: infringement depends on the objective characteristics of the product, including labelling and patient information leaflet, with the manufacturer’s intention being irrelevant. Lord Briggs and Lord Hodge preferred Arnold J’s subjective intention test (whether the manufacturer targeted the patent-protected market). Lord Mance held that the test depends on objective appearance and characteristics, but left open whether in rare cases the context might require positive exclusion of the patent-protected use. All agreed that on the facts, Lecaent was not presented as suitable for treating neuropathic pain, and Arnold J’s finding (para 661) that Actavis did not subjectively intend to target the patent-protected market stood. Even had the claims been valid, there would have been no infringement.

Implications

This decision is the leading United Kingdom authority on second medical use (Swiss-form) patents. Key principles emerging include:

• Plausibility is a substantive requirement of sufficiency: The specification must disclose scientific reasoning making the claimed therapeutic effect plausible across the scope of the claim. Mere assertion of efficacy is insufficient. While the threshold is relatively undemanding, it is not satisfied by speculation or ‘armchair’ claiming.
• Plausibility must be supported in the patent itself: Later published clinical data cannot substitute for inadequate disclosure, although such data may confirm or rebut a properly supported claim.
• Construction of broad claims: Where a claim encompasses multiple pathologies, plausibility must extend to all of them. Validating construction has limited modern application.
• Procedural discipline: Patentees must apply to amend in good time; post-judgment amendments raising fresh issues will generally be refused as abusive.
• Infringement of Swiss-form patents: The Court’s split on the appropriate test reflects the analytical difficulty of fitting Swiss-form patents into section 60 of the Patents Act, which was not designed for purpose-limited claims. Pharmacists, distributors and patients face uncertainty under section 60(1)(c) given strict liability for products obtained directly by an infringing process.

The judgment matters significantly to pharmaceutical patentees, generic manufacturers, pharmacists and the NHS. It limits the ability of innovators to obtain second medical use patents on speculative grounds, while raising the difficulty for patentees in enforcing such patents against generic competition with skinny labels. The fragmented infringement analysis leaves the test under section 60(1)(c) without binding ratio, and the Court acknowledged the legislation was not drafted with purpose-limited products in mind, suggesting any further reform is for Parliament. Swiss-form patents are now a closed class following EPC 2000, but the principles relating to plausibility and sufficiency continue to apply broadly to medical use patents.

Verdict: Warner-Lambert’s appeal dismissed; Actavis and Mylan’s cross-appeal allowed. Claims 1 and 3 of the patent held invalid for insufficiency; the application to amend was rightly refused as abuse of process; even if valid, the claims would not have been infringed.

Source: Warner-Lambert Company LLC v Generics (UK) Ltd (t/a Mylan) & Anor [2018] UKSC 56