Warner-Lambert Company LLC v Generics (UK) Ltd (trading as Mylan) and Others

Hearing dates: 23–26 May 2016

Approved Judgment

Introduction

In the various appeals which are before the court, three main questions arise. Firstly, did Arnold J correctly hold certain claims of the patent in suit invalid for insufficiency; and, if so, should he have held more claims invalid on that ground? Secondly, was he correct in holding the patentee's application to amend claim 3 of the patent, made after judgment on the issue of invalidity, to be an abuse of the process of the court? Thirdly, if there were any valid claims which were the subject of the allegation of infringement, was the judge correct to hold that there was no infringement of the (Swiss-form, second medical use) claims in the patent?

Warner-Lambert Company LLC ("Warner-Lambert") is the proprietor of European Patent (UK) No. 0 934 061. Although the title of the specification is "Isobutyl GABA and its derivatives for the treatment of pain", the derivative of interest is called pregabalin, to which the Swiss-form, second medical use claims are limited. Warner-Lambert markets pregabalin under its trade mark Lyrica for the treatment of neuropathic pain, as well as for its previously known indications of general anxiety disorder ("GAD") and epilepsy. It does so through Pfizer Ltd ("Pfizer"). Lyrica is one of the Pfizer Group's most successful products. Global sales of Lyrica amounted to approximately $4.6 billion in 2013 with UK sales in the same year amounting to approximately $310 million. Not surprisingly, this is a market of considerable interest to generic pharmaceutical manufacturers both for the existing medical indications and the new. I will refer to Warner-Lambert and Pfizer as "Warner-Lambert", without attempting to distinguish between them.

Procedural history

Generics (UK) Ltd, trading as Mylan, and Actavis Group PTC EHF ("Mylan" and "Actavis PTC") commenced separate claims for revocation of the patent on 24 June and 12 September 2014 respectively, relying on the grounds of lack of inventive step and insufficiency. On 8 December 2014 Warner-Lambert commenced a claim for infringement of the patent against Actavis PTC, Actavis UK Ltd and Caduceus Pharma Ltd. I will refer to all the Actavis companies and Caduceus as "Actavis".

Warner-Lambert applied for an interim injunction to restrain the sales of Actavis' generic pregabalin product, which was branded Lecaent. That application came before Arnold J, who dismissed it in a judgment dated 21 January 2015, see [2015] EWHC 72 (Pat). He did so on the twin grounds that Warner-Lambert had no arguable case of infringement, and that, in any event, the balance of justice favoured refusal of the injunction. Actavis then made an application to strike out Warner-Lambert's claim for infringement. That application also came before Arnold J, who struck out the claim for infringement insofar as it was made under section 60(2) of the Patents Act 1977 ("the Act"). Notwithstanding his earlier conclusion that Warner-Lambert had no arguable case of infringement, he allowed Warner-Lambert's infringement claim made under section 60(1)(c) of the Act to proceed to trial: see his two judgments, [2015] EWHC 223 (Pat) and [2015] EWHC 249 (Pat). In so doing, Arnold J recognised that the correct scope to be afforded to Swiss-form second medical use claims was a developing area of patent law. On 28 May 2015 this court dismissed Warner-Lambert's appeal against the refusal of the interim injunction but allowed an appeal against the striking out of the claim under section 60(2) of the Act: see [2015] EWCA Civ 556 (" Warner-Lambert CoA"). In so doing the court held that, on its view of the law and contrary to that applied by Arnold J, Warner-Lambert's infringement case under both subsections of the Act was arguable: see Floyd LJ at [133] and [140].

The actions themselves then came to trial, again before Arnold J, in June and July 2015. By then Actavis had retaliated with a counterclaim for groundless threats of patent infringement. Arnold J handed down his judgment ("the main judgment") on 10 September 2015: see [2015] EWHC 2548 (Pat). In the main judgment Arnold J held that:

i) none of the claims of the patent lacked inventive step over any of the prior art relied on by Mylan and Actavis;

ii) each of claims 1, 3, 4, 6, 13 and 14 of the patent was invalid on the ground of insufficiency;

iii) even if claims 1 and 3 had been valid, Actavis would not have infringed those claims pursuant to section 60(1)(c) or section 60(2) of the Act;

iv) in consequence, and as a result of certain letters sent out by Warner-Lambert, Pfizer was liable for making groundless threats of patent infringement proceedings.

The judge gave both Mylan and Actavis on the one hand and Warner-Lambert on the other permission to appeal against his decision on the issue of insufficiency, Mylan and Actavis contending that the judge should have made more extensive findings of insufficiency. The judge also gave Warner-Lambert permission to appeal in respect of his decision relating to infringement under section 60(1)(c), but not his decision under section 60(2). Floyd LJ later granted Warner-Lambert permission to appeal on the latter sub-section as well.

On 1 October 2015 Warner-Lambert made a conditional application to amend the patent. Insofar as these amendments consisted of deletion of entire invalid claims, they were uncontroversial. One amendment, however, sought to rewrite claim 3, the claim to the use of pregabalin to treat neuropathic pain, to add the words "caused by injury or infection of peripheral sensory nerves". By the addition of these words Warner-Lambert sought to limit the scope of the claim to peripheral neuropathic pain, and thus to exclude from its scope parts of the claim, in particular central neuropathic pain, that were found to be vulnerable to the insufficiency attack. This amendment was opposed by Mylan and Actavis. The judge directed that the question of whether that part of the application to amend was an abuse of the process of the court should be tried as a preliminary issue. In a further judgment ("the abuse judgment") given on 25 November 2015, [2015] EWHC 3370 (Pat), Arnold J decided that issue in favour of Mylan and Actavis without deciding the merits of the amendment application.

Technical background

There is a certain amount of technical background to be traversed before the issues can be addressed. The judge dealt with the background in paragraphs 37 to 82 of his judgment. Not all of that material is relevant to the issues which remain live on appeal. What follows is a highly abbreviated summary, based on that section of the judgment.

The nervous system

The nervous system comprises two main parts: the central nervous system and the peripheral nervous system. The central nervous system comprises the brain and spinal cord. The peripheral nervous system comprises the nerves outside those structures. The nervous system includes cells called neurons which transmit information through electrical and chemical signals.

Types of pain

At the priority date in 1996 pain was classified into a number of different types, although not all neuroscientists and clinicians would necessarily categorise pain types in precisely the same way.

i) Nociceptive pain occurs where stimuli such as heat, extreme cold, intense mechanical pressure and chemicals stimulate fibres known as nociceptors. The nociceptors then transmit impulses via the spinal cord to the brain where they are perceived as pain. Nociceptive pain has a bio-protective function in that it alerts the brain to the presence of the noxious stimulus so that appropriate avoidance measures can be taken. This type of pain resolves with treatment of the underlying cause.

ii) Inflammatory pain is a type of nociceptive pain. The body's response to an injury involves the release of chemical mediators which increase the sensitivity of nociceptors, causing pain both at the site of injury and in the surrounding area.

iii) Neuropathic pain is caused by damage to the nervous system itself. One definition of neuropathic pain is "pain initiated or caused by a primary lesion or dysfunction of the nervous system". The lesion or dysfunction can occur either in the peripheral nervous system or the central nervous system. Unlike nociceptive pain, neuropathic pain does not necessarily subside when the noxious stimulus is removed. A wide range of diseases may cause neuropathic pain by their effect on the nervous system. Two of the most common causes of neuropathic pain are diabetes and herpes, which can give rise to diabetic (peripheral) neuropathy ("DPN") and post-herpetic neuralgia ("PHN"), both examples of neuropathic pain.

iv) Peripheral neuropathic pain is the type of neuropathic pain where the lesion or dysfunction is in the...