Warner-Lambert patented the use of pregabalin to treat pain. Its experiments supported a use for inflammatory pain. Did they also disclose enough to justify a claim covering neuropathic pain, which arises from damage to the nervous system? A majority held that they did not. That distinction determined the validity of the challenged claims.
Warner-Lambert owned European Patent (UK) No 0934061, a Swiss-form second medical use patent with a priority date of 24 July 1996. Its principal claims were to the use of pregabalin (marketed as Lyrica) for the preparation of a pharmaceutical composition for treating pain (Claim 1), inflammatory pain (Claim 2) and neuropathic pain (Claim 3). Pregabalin itself was already known. Mylan and Actavis sought revocation for insufficiency. Warner-Lambert alleged that Actavis’s generic product Lecaent, launched under a skinny label indicating only epilepsy and generalised anxiety disorder, infringed Claims 1 and 3.
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Arnold J rejected the inventive-step challenge but held Claims 1 and 3 invalid for insufficiency. He found the specification supported efficacy for inflammatory pain and, narrowly, peripheral neuropathic pain, but not central neuropathic pain; because the claims extended to all pain and all neuropathic pain, they failed. Subsidiary claims that were or might be central neuropathic pain failed on the same ground. He refused a post-judgment application to amend Claim 3 so as to confine it to peripheral neuropathic pain, holding the application an abuse of process. The Court of Appeal upheld these conclusions (treating fibromyalgia as idiopathic rather than neuropathic, which did not affect the result) and differed from the judge on the hypothetical infringement test.
Construction and amendment
The Supreme Court unanimously affirmed that Claim 1 covers all pain and Claim 3 covers all neuropathic pain, peripheral and central. The skilled addressee—a team of a neuroscientist and a clinician specialising in pain—would have known the broad IASP definition distinguishing peripheral from central neuropathic pain. Nothing in the description narrowed the ordinary broad meaning of the claim language, which sat in a hierarchy of claims moving from the general to the particular. A presumption in favour of a validating construction was inappropriate. The Court also unanimously upheld the refusal of the amendment. Although section 75 of the Patents Act 1977 and article 138(3) EPC confer a right to seek amendment, national procedural rules, including the principles in Nikken and Nokia against vexing a party with a second trial that could have been avoided, permitted refusal where the point could and should have been raised in time for a single trial.
Sufficiency and plausibility
Sufficiency requires the specification to disclose the invention clearly and completely enough for it to be performed by the skilled person. For a Swiss-form claim the invention is not the known compound or its manufacture but the new therapeutic purpose. Both the domestic courts and the EPO have therefore required that the specification make the claimed efficacy plausible, so that the monopoly corresponds to a genuine technical contribution and purely speculative claiming is prevented. Plausibility is part of the sufficiency inquiry, not a free-standing condition. It is a relatively low threshold, reflecting the practical need to file before clinical trials, but it is not satisfied by a bare assertion, a mere possibility, or a prediction based on nothing more than that something is worth trying.
Lord Sumption (with whom Lord Reed and Lord Briggs agreed) held that the assertion of efficacy must be plausible across the whole scope of the claim, judged on the disclosure read with common general knowledge at the priority date. Later clinical data cannot cure an insufficient disclosure, though they may sometimes confirm a disclosure that was already plausible or answer a positive challenge that the invention does not work. The animal-model data in the patent (including the rat paw formalin test) supported efficacy for inflammatory pain. They did not, and the specification did not claim that they did, make efficacy for neuropathic pain plausible. Central sensitisation, though involved in both inflammatory and peripheral neuropathic pain, was not shown to be a unifying mechanism that pregabalin could be expected to affect, and it could not explain central neuropathic pain. The judge’s conclusion that peripheral neuropathic pain was “just” plausible did not follow from his own findings. Claims 1 and 3, and the other claims relating to neuropathic pain, therefore failed for insufficiency. Lord Hodge and Lord Mance considered the plausibility threshold lower and would have accepted the judge’s evaluation that the disclosure just made peripheral neuropathic pain plausible, so that certain narrower claims could have survived; they were in the minority on this issue.
Infringement
The claims being invalid, infringement did not arise for decision. Given the general importance of the point, however, the Court addressed the test for direct infringement under section 60(1)(c) of a purpose-limited process claim. All the justices rejected a test based on mere foreseeability that some of the generic product would be dispensed for the patented use (whether or not qualified by a requirement to take all reasonable steps to prevent leakage). Such a test would give inadequate certainty, expose downstream pharmacists and others to strict liability they could not reliably avoid, and risk extending protection into patent-expired uses.
The justices differed on the correct positive test. Lord Sumption and Lord Reed held that the manufacturer’s intention is irrelevant. The sole criterion is the outward presentation of the product as it emerges from the manufacturing process, including its packaging, labelling and patient information leaflet: whether it is presented as suitable for the patent-protected use. Lord Mance likewise focused on the objective characteristics of the product as prepared, presented and put on the market, while leaving open whether rare cases of context or a positive exclusion might alter the conclusion. Lord Hodge and Lord Briggs preferred the view that the test is the manufacturer’s subjective intention to target the patent-protected market, provable by any evidence and not confined to packaging; Arnold J had found no such intention. All agreed that, on the facts found, the claims would not have been infringed even if valid. A claim of indirect infringement under section 60(2) also failed: the protected invention is the manufacturing process, which is complete once manufacture ends, and does not extend to later dispensing or use.
Verdict: The Court dismissed Warner-Lambert’s appeal and allowed the generics companies’ cross-appeal. The challenged claims were invalid for insufficiency. The Court upheld the refusal of the late amendment. Its discussion of infringement assumed, contrary to the decision on validity, that the claims were valid.
Source: Warner-Lambert Company LLC v Generics (UK) Ltd t/a Mylan and another [2018] UKSC 56
