Warner-Lambert Company LLC v Generics (UK) Ltd (t/a Mylan) & Ors

A pharmaceutical second-medical-use claim is insufficient if the patent does not make it plausible that the treatment will work across substantially all of its scope. Plausibility is a low threshold: it excludes speculative claiming but does not require a reasonable prospect of success or a firm prediction of efficacy. Later evidence may confirm an existing basis for prediction, but cannot supply a basis absent from the patent.

A post-trial rewriting amendment which could and should have been advanced before trial may be an abuse of process where it opens a new route to success and risks further validity and allowability disputes. For Swiss-form claims, the relevant purpose is assessed objectively; a manufacturer may negate intention by taking all reasonable steps within its power to prevent use for the patented indication.

Warner-Lambert owned a patent for the use of pregabalin in treating pain. Generic manufacturers sought revocation for insufficiency. Warner-Lambert alleged that Actavis’s generic product infringed Swiss-form, second-medical-use claims.

Arnold J held claims including the broad pain claim and the neuropathic-pain claim invalid for insufficiency, while finding a claim confined to peripheral neuropathic pain plausible. He also held that Warner-Lambert’s later conditional application to rewrite claim 3 was an abuse of process: [2015] EWHC 2548 (Pat); [2015] EWHC 3370 (Pat).

The appeals concerned the correct plausibility standard, the construction and sufficiency of the claims, the proposed amendment, and, if valid claims remained, direct and indirect infringement under the Patents Act 1977.

1. Appeals dismissed. Floyd LJ, with whom Kitchin and Patten LJJ agreed, upheld the invalidity findings and the refusal to permit the post-judgment amendment. The infringement claim therefore failed.

2. The relevant insufficiency inquiry is whether the patent gives a reasonable basis for predicting that the invention will work with substantially everything within the claim. The plausibility requirement is a low threshold directed against speculative monopolies. It does not require a reasonable prospect of success. Post-published evidence can support, but cannot itself establish, plausibility.

3. Claim 1 covered pain generally. The specification’s examples and its reference to antihyperalgesic action did not redefine or narrow that expression. Claim 3’s reference to neuropathic pain included central as well as peripheral neuropathic pain. The central subset included important conditions and was neither artificial nor immaterial. The patent supplied no plausible basis for efficacy in central neuropathic pain; consequently claim 3 was insufficient across its breadth.

4. The court upheld the finding that the patent did just make efficacy plausible for peripheral neuropathic pain. The shared role of central sensitisation in inflammatory and peripheral neuropathic pain, together with the disclosed data and simple confirmatory tests, supplied a sufficient unifying basis.

5. The proposed rewriting amendment was properly treated as abusive. It gave Warner-Lambert an alternative route to success, independent of its unsuccessful construction argument. It could and should have been conditionally advanced before trial, allowing all validity and allowability issues to be managed together. A party resisting a late new point need not specify the evidence it might have adduced; any material doubt as to prejudice favours that party.

6. The court nevertheless addressed Swiss-form infringement obiter. A manufacturer’s purpose is objective: it ordinarily intends an intentionally patented use which it knows or can reasonably foresee. A skinny label alone is insufficient. Intention is negatived where the manufacturer has taken all reasonable steps within its power to prevent the patented use. Under section 60(2), relevant preparation can include pharmacists’ acts; a downstream act need not be characterised narrowly as manufacture.

• Court of Appeal (Civil Division): Warner-Lambert’s appeals and the generic manufacturers’ cross-appeals were dismissed: [2016] EWCA Civ 1006.

• High Court, Patents Court: Arnold J held material claims insufficient and dismissed the infringement claim: [2015] EWHC 2548 (Pat).

• High Court, Patents Court: Arnold J held Warner-Lambert’s post-judgment conditional application to amend claim 3 to be an abuse of process: [2015] EWHC 3370 (Pat).