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Second Medical Uses: when is a drug prescribed "for" pain?

Date: 21 January 2019

We have previously reported on the preliminary proceedings in a battle between WarnerLambert, owner of a patent for a second medical use for pregabalin, and Actavis[1], a generic manufacturer that supplied pregabalin for its off-patent indications. In proceedings in 2015, Warner-Lambert were denied interim relief because, according to the judge, a Swiss form claim requires subjective intent on the part of Actavis that the drug would be used for the treatment of pain.

 

The matter went to trial and proceeded all the way to the Supreme Court, where Warner-Lambert finally lost because the claim to use of the drug “for pain” was over-broad given that the description taught only that the drug worked for certain types of pain (inflammatory pain).

 

Pain comes in various forms: there is nociceptive pain produced by noxious external stimuli such as heat, injury or chemicals; there is inflammatory pain; and there is neuropathic pain which is caused by damage to the nervous system itself. There are many medicines for inflammatory pain. It is treatment of neuropathic pain that is of greater interest in sales of pregabalin.

 

Warner Lambert had set out tests on rats demonstrating efficacy of pregabalin for treatment of inflammatory pain, but not for neuropathic pain. Neither was there any unifying principal or theory set out to extrapolate from the results to their application to neuropathic pain.

 

Applying Conor Medsystems v Angiotech [2008] RPC 28, it was not enough that there was disclosure of a mere possibility that pregabalin might be efficacious for neuropathic pain. That would be no better than a bare assertion. The presence of a cause/effect relationship must be plausible from the patent specification[2]. In this case, it was not. 

 

Comment - Sufficiency

 

The Court did not wish to reward “armchair inventors”- persons who have simply sought to patent abstract possibilities. Something valuable may have been invented, but the contribution must be sufficiently disclosed in the patent. Experimental data is useful but not necessary.

 

The court went further than the EPO Boards of Appeal by saying the requirement for plausibility is not met by a bare or dubious assertion in combination with common general knowledge or post-published evidence. A priori reasoning may suffice, but it must be set out in the patent application itself.

 

Comment – Infringement of Swiss-type claims

 

On the question of whether a Swiss-type claim is infringed only where there is subjective intent on the part of the manufacturer, the five judges were divided, with two preferring the subjective intent test, two preferring an objective test based on product with its labelling and accompanying leaflet and the fifth preferring the objective test but leaving open the possibility that in the facts of a future case, additional extrinsic evidence might be relevant.

 

The EPO no longer grants Swiss-type claims on patent applications having a filing or earliest priority date of 29 January 2011 or later (see OJ EPO 2010, 514).[3] So the debate over subjective intent,
if not fully settled by this decision, is likely to die when the last SPC on the last Swiss-type claim expires. In the meantime (with limited exceptions) infringement is to be determined by what the court referred to as the “outward presentation” test – i.e. the physical characteristics of the product as it emerges from the relevant process (manufacture or repackaging) including its formulation and dosage, packaging and labelling and the accompanying patient information leaflet (so-called “skinny label”).

 

[1] Generics is the first named defendant, as they first applied to revoke the patent, but Actavis holds the marketing authorization, so Warner-Lambert counterclaimed against Actavis for infringement. Warner-Lambert is owned by Pfizer.

 

[2] EPO decisions T609/02 - SALT INSTITUTE/AP-I complex and T0578/06 - IPSEN/Pancreatic cells.

 

[3] Instead, claims take the form “substance X for use in the treatment of disease Y”.

  

You can find this article and others in our Patent Issues Newsletter Spring 2019.

 

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