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Inside IP: Court of Appeal finds pregabalin second medical use patent invalid
 Briefing 
Author
David Rose & Nina O'Sullivan
Date
17 October 2016

Inside IP: Court of Appeal finds pregabalin second medical use patent invalid

The Court of Appeal has delivered its much-anticipated decision in the dispute concerning Warner-Lambert's second medical use patent for pregabalin, and skinny labelled generic products. Pregabalin is marketed by Pfizer under the brand name Lyrica (with global sales in 2013 of approximately $4.6 billion). The Supplementary Protection Certificate for pregabalin expired in October 2013 but Warner-Lambert has a second medical use patent for the use of pregabalin for the treatment of pain, including neuropathic pain. The dispute relates to the launch of generic pregabalin in the UK under a so-called 'skinny label', i.e., limited to non-patented indications of epilepsy and generalised anxiety disorder.  

In September 2015, Arnold J decided that the relevant claims of the Patent were invalid for insufficiency. He subsequently decided that it would be an abuse of process for Warner-Lambert to amend a claim of the Patent to limit its scope and thereby exclude part of the claim vulnerable to the insufficiency attack.

The Court of Appeal has now rejected Warner-Lambert's appeal, upholding the Judge's conclusions on invalidity and refusal of its application to amend the Patent. Despite finding the relevant claims invalid, however, Floyd LJ returned to the important issue of infringement of second medical use patents, following the decision he gave on this issue in the Court of Appeal in May 2015 (in relation to Warner-Lambert's application for an interim injunction). In that decision, Floyd LJ said that the word 'for' in a Swiss-form second medical use claim imported an objective test - i.e., the skilled person would understand a patentee of a second medical use claim to be using the word 'for' in the claim to require that a manufacturer knows (including having constructive knowledge) or can reasonably foresee the ultimate intentional use (in this case, for pain), and not that they have that specific intention or desire. 

Whilst Arnold J had "loyally" applied this decision - albeit, again, only on the basis that, contrary to his conclusion, the claims were valid - he had expressed "profound reservations" about the law to be applied, and so the Court of Appeal considered it appropriate to revisit this issue. In particular, Floyd LJ carefully considered Actavis' argument based on decisions in European countries, but affirmed the basic objective test previously adopted in the Court of Appeal. Once the existence of intention was made out on this test, it could be negatived if the manufacturer had taken all reasonable steps within its power to prevent the foreseen consequences occurring. As Floyd LJ put it, the Court of Appeal's approach was an attempt to "strike the right balance by not placing insuperable obstacles in the path of the patentee, whilst at the same time recognising in very clear terms that the remedies available for infringement will have to be moulded so as to achieve fair and proportionate relief tailored to the very special circumstances of the case".

BACKGROUND

The case concerns Warner-Lambert's second medical use patent (EP (UK) 0 934 061) for the use of pregabalin for the treatment of pain, including neuropathic pain. Warner-Lambert argued that the launch of generic products under a skinny label amounted to both direct and indirect patent infringement. The relevant claims in the Patent are Swiss-form second medical use claims – i.e., "use of substance X for the preparation of a medicament (or pharmaceutical composition) for treating indication Y".

At trial, Arnold J decided that a number of claims in the Patent were invalid on the grounds of insufficiency, in particular Claims 1 and 3:

Claim 1 - "Use of [pregabalin] or a pharmaceutically acceptable salt thereof for the preparation of a pharmaceutical composition for treating pain"

Claim 3 - Use according to claim 1, where the pain was neuropathic pain.

In a later hearing Arnold J rejected Warner-Lambert's conditional application to amend Claim 3 of the Patent to exclude from its scope 'central neuropathic pain'.

COURT OF APPEAL DECISION

Validity - Insufficiency

Before considering the insufficiency issue in detail, Floyd LJ reviewed a series of UK and EPO case law considering the requirement that the specification should make the invention plausible or credible. These cases indicated that the plausibility requirement was a low threshold: designed to prohibit speculative claiming, but not to prohibit patents for good faith indications with some basis, even if manifestly incomplete (albeit such claims could turn out to be insufficient if the prediction proved untrue).  

Floyd LJ said that Arnold J was right to conclude that Claim 1 and 3 were not plausible across their breadth.  Specifically, in relation to Claim 3, the skilled person would know from the common general knowledge definition of neuropathic pain that it divided naturally into two parts, central and peripheral neuropathic pain, and therefore to divide the claim in this way was "neither unrealistic nor unfair". The case was a "long way" from a case where an insufficiency attack focuses on a contrived or artificial part of the claim and where, as a consequence, the attack does not undermine the validity of the claim as a matter of substance.

However, whilst there was no basis to ignore that part of the claim relating to central neuropathic pain when considering whether the claim was plausible, Arnold J was correct in deciding that the Patent did make a plausible claim that pregabalin was effective to treat peripheral neuropathic pain. This finding was relevant to the abuse of process argument.

Amendment post-judgment - Abuse of process

Following Arnold J's decision on validity, Warner-Lambert had unsuccessfully applied to amend Claim 3 to limit the claim to peripheral neuropathic pain. Warner-Lambert faced an "uphill task" on its appeal as it is rare that an appeal Court will interfere with a decision of a lower court as to whether conduct is abusive, given the evaluation of a range of factors. Specifically, in relation to rewriting validating amendments post-trial, Floyd LJ noted that they are particularly unlikely to be allowed post-trial because they create new issues which typically are unlikely to have been decided at trial.  

The Court of Appeal agreed with Arnold J that it would be an abuse of process for Warner-Lambert to amend the claim in this way, even though the amendment sought was intended to give effect to the construction of Claim 3 for which it had argued at trial. Warner-Lambert could have overcome this by showing that it had a good reason for not raising it at trial but it was unable to do so. The Court considered it should have indicated, no later than the start of the trial that, if there was an adverse finding, it would seek to amend. 

Infringement of second medical use claims

Given the findings on validity, it was not necessary for the Court of Appeal to revisit the question of infringement of Swiss form claims. However, whilst Arnold J had applied the Court of Appeal's May 2015 decision on this, Floyd LJ recognised he had "obviously profound reservations about the law". This meant the Court of Appeal should review the principal arguments, even though this was no longer necessary.

Floyd LJ began by reviewing a series of cases from other jurisdictions, including Germany, Spain, France, Denmark, The Netherlands and the EPO.  He concluded that these showed there was no universal principle, but rather a spectrum of different approaches – with some countries (e.g., Germany) applying the 'only packaging will do' approach, others (e.g., Spain) looking more generally for some element of encouragement of the use of the drug for the new use by the manufacturer, and others (e.g., France) looking to see what steps have been put in place in the marketplace to prevent use for the prohibited indication.   

Actavis argued that the Court of Appeal's approach was out of step with the main stream of this European authority. It argued for a requirement that the manufacturer "aims for or targets" the patented indication – adopting this approach, it argued, the manufacturer has control over whether it infringes. Floyd LJ noted that he had, in the Court's May 2015 decision, recognised that a situation where a manufacturer foresees a use for the patented treatment but takes all reasonable steps in its power to prevent it happening represented a 'hard case'. However this did not mean that the test should be one of purely subjective intention, and he had no doubt that an objective approach was necessary. But, whilst that was the basic test, the intention would be negatived where the manufacturer took all reasonable steps within its power to prevent the foreseen consequences occurring: in those circumstances, it could be said that the foreseen consequences were not intended and were in fact an unintended incident of the manufacturer's otherwise lawful activity. 

Applying this approach to the facts of the case (purely on the assumption the Patent was found valid), Arnold J should have decided whether, at the various relevant dates, Actavis knew or could foresee that at least some of the prescriptions written generically for pregabalin to treat pain would in fact be fulfilled by its product. If that was the case, he should then have gone on to consider whether Actavis had taken all reasonable steps in its power to prevent its product from being used to treat pain.

On indirect infringement, Floyd LJ agreed with Warner-Lambert that acts of the pharmacist in preparing the composition for delivery to the patient could be regarded as relevant acts of preparation, if done with the necessary intention. The relevant claims are processes of manufacture and Arnold J had said the "fundamental difficulty" of a claim of indirect infringement was there was no act of manufacture downstream from Actavis, in particular by pharmacists, nor any prospect of it. Floyd LJ disagreed with Arnold J's approach, noting there was a danger in requiring there to be a 'downstream act of manufacture'; the requirement was that there was provision of means for putting the invention into effect. 

Comment

The Court of Appeal has confirmed and justified its approach to the question of infringement of second medical use patents (albeit its comments remain obiter). Ultimately, this may be an issue for the Supreme Court to grapple with.  

As Floyd LJ put it, the Courts face a difficult issue:

"The law is struggling on the one hand to give the patentee a proper reward for his contribution to the art by elucidating the new use for the drug, whilst at the same time not excluding the competing manufacturer from making and marketing the drug for its known purpose. The issue is complicated by the interaction with the law relating to, and the practice in, prescription medicines".

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