A recent decision of the UK’s High Court provides a comprehensive analysis of the issues that should be considered when determining infringement of second medical use claims.

Background

Warner-Lambert Company LLC (Warner Lambert), part of the Pfizer group, markets the prescription drug pregabalin under the trade mark LyricaTM for epilepsy, generalised anxiety disorder (GAD) and neuropathic pain. Patent protection for the drug per se expired in 2013 but Warner Lambert do have a second medical use patent (EP0934061) in force directed to pregabalin for treating pain, and in particular neuropathic pain.

The key claims, claims 1 and 3, are in the ‘Swiss form’ and recite, as follows:

“1. Use of [pregabalin] or a pharmaceutically effective salt thereof for the preparation of a pharmaceutical composition for treating pain.
3. Use according to claim 1 wherein the pain is neuropathic pain.”

Actavis have applied for and are on the verge of obtaining a so-called ‘skinny label’ marketing authorisation for generic pregabalin limited to epilepsy and GAD. Once they have obtained their generic marketing authorisation they plan to launch their product under the trade mark LecaentTM. A number of other generic suppliers have also shown signs of making preparations to launch generic pregabalin.

Actavis has taken or has proposed to take a number of steps to avoid LecaentTM from being prescribed for the treatment of pain. Warner Lambert is concerned that LecaentTM will be used to treat pain despite the marketing authorisation being limited to epilepsy and GAD.

Whilst a full trial concerning the validity and infringement of the second medical use patent is due to take place in June 2015, Warner Lambert sought interim relief to try to impose certain duties on Actavis to ensure that LecaentTM would not be dispensed for use in the treatment of pain (see para. 78 of the decision).

In coming to a decision, Mr Justice Arnold provided an analysis of second medical use claims, namely claims to second and subsequent medical uses of known compounds. Whilst second medical use claims could not prevent third parties entering the market with a drug for any non-patented indications, in practice, ‘off-label’ use of a generic drug for a patented indication may occur, particularly where the dosage of the two is the same. Further, in the UK, medical practitioners are encouraged to prescribe generically which provides pharmacists the freedom to dispense branded or generic versions of a drug. In contrast, if a specific brand is identified on a prescription then that brand must be dispensed. Warner Lambert were concerned that off-label use would be made of Actavis’ drug.

Actavis successfully argued that infringement of a Swiss claim required demonstration of a ‘subjective intention’ for the drug to be used for the patented indication. Whilst Warner Lambert failed to demonstrate such an intention on the part of Actavis, they have reserved the right to submit evidence later this year in the full trial.

When assessing whether to grant interim relief, Justice Arnold considered the balance of risk of injustice, taking into account the relative harm to each party should relief be granted or refused and the ease of assessing damage. Interestingly, the judge was swayed "strongly" by the fact that even if marketing with a label setting out the situation and existence of a patent for a particular indication and the explicit non-use for the treatment of pain, Actavis may have been effectively prevented from performing acts that were perfectly permissible, for example, the sale of pregabalin for epilepsy and GAD. In light of the circumstances (see in particular para. 128), Justice Arnold held that Actavis are likely to suffer substantial unquantifiable loss should the relief be granted.

Impact of the decision

This is the first decision handed down by a UK judge considering the construction of second medical use claims. It is very interesting to see that the ‘subjective intention’ of the manufacturer of the drug complained of matters when assessing the infringement of a Swiss form medical use claim.

Importantly, EPC 2000 second medical use claims have a different scope of protection to Swiss form claims and Justice Arnold was particular in pointing this out:

“It should not be assumed that anything I say in this judgment about Swiss form claims necessarily applies to EPC 2000 claims”

You will recall that EPC 2000 claims have the form: “Product X for use in the treatment of indication Y”. Swiss form claims are being phased out in Europe and are only permissible in patents and applications filed before 29 January 2011. On or after that date must use the EPC2000 form.

Furthermore, at first sight, this decision appears to be at odds with a recent decision of the Dutch Court of Appeal in the Hague between Novartis and Sun Pharmaceuticals. Sun was found liable for the indirect infringement of a Swiss form claim despite them applying a skinny label which did not mention the patented use.

However, there are differences: firstly, the Dutch judgment was reached under Article 73 of the Dutch Patent Act relating to indirect infringement whereas the UK judgment was reached under provisions governing the infringement of process claims; and, secondly, Justice Arnold in the UK did not consider indirect infringement to be relevant as that would require Actavis to be supplying an essential means to prepare the composition which they were clearly not doing, they were manufacturing the drug themselves.

It appears difficult to enforce Swiss form claims against skinny label generic drugs. Whilst Swiss form claims are no longer available for new applications, it will be some time before exisitng patents and applications containing them will expire.