IP Cases & Articles

Warner Lambert v Actavis: Swiss form claims 

​The Court of Appeal has decided the latest instalment of the pregabalin second medical use litigation between Warner-Lambert (part of Pfizer) and Actavis (and other generics manufacturers) in the UK.

Readers may recall that this case has featured in our August and October 2015 newsletters, which reported the Court of Appeal's decision on preliminary applications for an interim injunction and a strike-out of part of Warner-Lambert's case, and the substantive decision at First Instance. Readers may also recall a distinct difference of opinion between Lord Justice Floyd in the Court of Appeal and Mr Justice Arnold in the Patents Court as to the meaning and application of Swiss Form claims, as a matter of both direct and indirect infringement.

Background

Pregabalin is sold by Pfizer as Lyrica® for three labelled indications: epilepsy, generalised anxiety disorder and neuropathic pain. The basic patent, which disclosed the epilepsy and anxiety indications, expired in 2013, after which generics manufacturers prepared to launch generic pregabalin with a 'skinny label' omitting the neuropathic pain indication which is the subject of the patent below. Some also took further steps to inform pharmacists and health professionals that the drug was not to be prescribed for the treatment of pain.

The claimed invention

The patent in suit, EP 0 934 061 (as centrally limited at the European Patent Office - EPO), was directed to pregabalin for the treatment of pain. Two claims were alleged to be infringed, claims 1 and 3. Claim 1 was a Swiss form claim to the "use of [pregabalin] for the preparation of a pharmaceutical composition for treating pain". Claim 3 was limited to treating neuropathic pain.

The issues in the case

There were three principal issues in the case: validity (in particular, insufficiency); amendment; and infringement. The Court of Appeal upheld Arnold J on the first two issues, but disagreed with him (as it had at the interim stage) on the third.

Insufficiency

The insufficiency attack centred on whether the animal tests disclosed in the patent in suit were sufficient to render it plausible that pregabalin would work (a) for the treatment of pain generally (claim 1) and (b) for all kinds of neuropathic pain (claim 3).

The requirement that the application as filed makes the invention 'plausible' has been raised before both the EPO and national courts under the headings of insufficiency, inventive step and industrial applicability. Generally, the plausibility requirement is aimed at preventing speculative claiming and avoiding the grant of a monopoly over a field of endeavour in which the inventor has made no contribution.

The Court of Appeal confirmed that the plausibility requirement for the purposes of sufficiency is not the same as that for inventive step: for the purposes of sufficiency, the specification did not have to provide enough information that rendered the claimed invention "obvious to try with a reasonable expectation of success", which concerns inventive step. On the contrary, plausible speculation that fell short of providing any such expectation of success would be enough for sufficiency. It is a low threshold test: the claim will not be seen as speculative when the inventor provides a reasonably credible theory as to why the invention will or might work. Data can be produced later either to support or rebut plausibility, although the court made it clear that such data could not be filed in order to establish plausibility itself. The specification itself must do that much.

Equally however, the Court of Appeal confirmed that plausibility must be established across the breadth of the claim. On the evidence, the animal tests related to inflammatory pain and could also support a claim to peripheral neuropathic pain, but there was no unifying characteristic for all of the types of pain that were claimed and/or for which the animal studies provided plausible support. Accordingly, only the claims for which the animal models provided a plausible model were sufficient.

This was essentially the end of the matter as regards claim 1 (treatment of pain generally) but not claim 3, which as noted above was to neuropathic pain. On this issue, two kinds of neuropathic pain were relevant – central and peripheral. The expert evidence was such that while the animal models were good enough to support a claim to the treatment of peripheral neuropathic pain, the same could not be said of central neuropathic pain. Warner-Lambert therefore sought to argue that the claim as properly construed was limited to peripheral neuropathic pain, an argument rejected by both the Patents Court and the Court of Appeal.

Accordingly, the Court of Appeal upheld the judge's finding of insufficiency of both claims 1 and 3. The court ruled that the fact that pregabalin had subsequently been authorised for central neuropathic pain could not justify a claim that was speculative when it was made.

Amendment

At first instance, having lost on sufficiency of claim 3 and seeing in the judgment that a claim limited to peripheral neuropathic pain would have been sufficient, Warner-Lambert sought a post-judgment amendment to make this limitation. There is a consistent line of authority in the UK that post-judgment amendments are permissible to the extent they delete invalid claims, but not where they involve re-writing existing claims. The reasoning is simple – such an amendment should be brought early enough in the case to allow all issues relating to it, including inventive step, novelty and allowability, to be addressed. Inventive step and novelty in particular have to be considered at trial because expert evidence may well be required. The UK courts will not allow amendments that would require a second trial.

Warner-Lambert argued that because the sufficiency of a claim limited to peripheral neuropathic pain had been decided by the judge the amendment should be allowed. They further argued that Actavis's case on sufficiency had not been made clear until late in the proceedings, and they had been prejudiced as a result.

The judge had rejected these arguments, and he was upheld by the Court of Appeal. At trial, Warner-Lambert had clearly argued the point as a matter of claim construction. Accordingly they had been sufficiently aware of the issue. A conditional amendment could have been sought at the commencement of the trial if desired, to cover the situation that their construction was wrong, but it wasn't. Further, while sufficiency may have been addressed at trial, this did not mean that other aspects had been. In particular, the court noted that Actavis's approach on inventive step may have differed if faced with the proposed amended claim.

In the light of this and previous case law (Nikken v Pioneer [2005] and Nokia v IPCom [2011]), the Court of Appeal upheld the judge's refusal to allow a post-judgement amendment, as an abuse of process.

Infringement of Second Medical Use Claims (Swiss Form)

As the claims that were alleged to be infringed had been found invalid, it was not necessary for the Court of Appeal to render a decision on infringement. However, in light of the difference of opinion between Arnold J and the Court of Appeal on both direct and indirect infringement, Floyd LJ took the opportunity to reiterate his views.

On direct infringement, Floyd LJ repeated his view that the words "for the treatment of..." in Swiss form claims imported an objective intention as to the ultimate use of the medicament, rejecting once again the 'subjective intention' test of the lower court. Accordingly, where a manufacturer knows or can reasonably foresee that the medicament will be used for the patented use, there is prima facie infringement. That intention can be negated where the manufacturer takes all reasonable steps within his power to prevent that use. The court did not give guidance on what "all reasonable steps within his power" might entail but the message seems to be clear enough: reliance on a 'skinny label' alone will not be enough and positive steps must be taken to try prevent the drug from being used for the patented process.

As for indirect infringement, a cause of action rejected by Arnold J as essentially unarguable, Floyd LJ explained his view as previously expressed at the interim stage. Arnold J had decided that because there was no downstream act of manufacture and bearing in mind Swiss-form claims are process claims, there could be no supply of means relating to that invention by the upstream manufacturer. Floyd LJ noted instead however that "preparation" for the purposes of a Swiss-form claim can include a packaging step and/or a labelling step, the latter potentially being carried out by a (downstream) pharmacist. Accordingly, the supply by the original manufacturer could fall within the indirect infringement provisions of the Patents Act 1977.

Conclusion

This judgment leaves four clear points to bear in mind.

  1. While the test of plausibility for sufficiency is not the same as for inventive step, the patent itself must contain sufficient information to make the claimed invention plausible across its breadth: if it does not, later-generated data may not remedy this defect.
  2. Re-writing amendments post judgment is unlikely to be possible in the UK: always consider a conditional amendment before trial if arguing a crucial point of claim construction.
  3. The relevant intention for direct infringement of second medical use claims is an objective one, viewed from the point of the manufacturer.
  4. Swiss form claims can be infringed indirectly based on downstream preparatory steps.

Case details at a glance

  • Jurisdiction: England & Wales
  • Court: Court of Appeal (Civil Division)
  • Parties: Warner-Lambert Company LLC (appellant) and Generics (UK) Limited (trading as Mylan), Actavis Group PTC EHF, Activis UK Limited and Caduceus Pharma Limited (respondents) and the Secretary of State for Health (intervener).
  • Citation: [2016] EWCA Civ 1006
  • Date: 13 October 2016
  • Full decision: http://dycip.com/ewcaciv20161006

Useful links

Nikken v Pioneer [2005] full decision: http://dycip.com/nikkenvpioneer

Nokia v IPCom [2011] full decision: http://dycip.com/nokiavipcom

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