At the time of writing this article, Warner-Lambert and Pfizer have already been before the U.K. courts at least seven times in 2015 in disputes over the drug pregabalin.  The patent protection for pregabalin itself expired in 2013.  Warner-Lambert also has a later-filed second medical use patent including claims in the “Swiss form,” directed to the use of pregabalin in the manufacture of a medicament for treating pain. 

Warner-Lambert licensed the patent to Pfizer, which holds the marketing authorization for the pregabalin product Lyrica.  Its regulatory data protection for this product expired in July 2014, and immediately after that expiry, Actavis applied for marketing authorization to sell generic pregabalin under a “skinny label” that referred only to the treatment of anxiety and epilepsy. 

It is common in the U.K. healthcare system for doctors to prescribe drugs based on their International Non-Proprietary Name (e.g., pregabalin), rather than using the brand name of the drug product (e.g., Lyrica).  Pfizer therefore sought to prevent Actavis (and others) from selling pregabalin in the United Kingdom on the basis that, irrespective of what was stated on the label, it would in practice be prescribed and used for the treatment of pain. 

Patent Infringement
Among the many issues considered across these decisions, one of the most interesting related to infringement, and whether Actavis’s manufacture and sale of pregabalin under a skinny label that did not mention the treatment of pain would be an infringement of such a second medical use claim.  Despite having been used in Europe since the 1980s, there has been very little litigation that has considered the scope of the Swiss-form claim, and what is actually required to show infringement.  One of the key issues considered in these Warner-Lambert decisions was the effect of the limitation “for treating” in such a claim. 

Early in 2015, the High Court judge, Justice Arnold, concluded that “for treating” requires subjective intent on the part of the manufacturer that its product be used for the patented indication.¹  The Court of Appeal disagreed, and concluded that proof of intent by the manufacturer was not required, only that it was reasonably foreseeable to the manufacturer that the drug would intentionally be used to treat the patented condition.² 

The case then returned to Justice Arnold in the High Court, where he followed the Court of Appeal’s foreseeability test, but found there was no infringement by Actavis.³  He reasoned that the Court of Appeal’s test still required proof of intention, but that it shifted the intention from the manufacturer to the downstream suppliers/users of the product.  He concluded that a doctor who prescribes a drug using its International Non-Proprietary Name does not specifically intend for the Actavis product to be used.  Similarly, he found that the pharmacist who supplied the drug will generally not know which condition the drug will be used to treat, so has no specific intention to provide the Actavis product for the patented indication.  Finally, Justice Arnold concluded that the patient being treated has no specific intention to use Actavis’s product to treat pain because the patient will simply do what the doctor instructs, without having any input on the choice of drug.

Justice Arnold therefore concluded that the instances of actual infringement (e.g., where the pharmacist prescribes Actavis’s drug despite knowing that it will be used to treat pain) were de minimis and that there was therefore no case for infringement of the patent by Actavis.

The End of the Matter?
Justice Arnold has granted Warner-Lambert leave to appeal against his decision on infringement, so we may yet see further developments from the Court of Appeal in this case.  It will be interesting to see whether they agree with the way in which Justice Arnold applied their “foreseeability” test.

Second Medical Use Claim Formats
The claims in this case are in the Swiss form, which is considered to be a process claim directed to a manufacturing step in which a medicament is produced.  However, since December 2007, the European Patent Office (EPO) has also allowed claims in the purpose-limited product format: “product X for use in a method of treating disease Y.”  Indeed, this is the only second medical use claim format allowed by the EPO on more recent patent applications.  This new claim is considered to be a product claim rather than a process claim, and the EPO and others have suggested that it may have broader scope than the equivalent Swiss-form claim. 

It is unclear whether the same conclusions would have been reached by the U.K. courts if the claims had been in this purpose-limited product format.  The product claim still includes a feature of “for use in” and so it is possible that the same question of specific intent by the ultimate supplier or user of the drug may still apply. 

An Alternative Approach?
Justice Arnold suggested that second medical use claims should be enforced by improving the system for drug prescriptions in the United Kingdom to ensure that only the branded product produced under license from the patent proprietor was used to treat the patented indication.

In one of the decisions in this series, Pfizer successfully obtained an injunction against NHS England (which oversees the operations of the English National Health Service), requiring them to instruct doctors to prescribe pregabalin only by the Pfizer brand name Lyrica when it was for use in treating pain.⁴  The pharmacist would then be required to dispense only the Pfizer product against that prescription. 

This appears to have been somewhat successful for Pfizer: NHS England guidance has been updated to reflect this requirement, and the proportion of pregabalin prescribed by reference to the brand name Lyrica had risen to 34% by October 2015 (from as little as 1% in January 2015).  However, this compares with an estimate that 70% of pregabalin prescriptions in the United Kingdom are for the treatment of pain.  It therefore appears likely that this approach has not yet succeeded in preventing “skinny label” pregabalin being supplied for the patented indication in the United Kingdom.  Justice Arnold has suggested that a more effective system of guidance, and enforcement of that guidance, is still required. 

¹ Warner-Lambert Co. v. Actavis Grp. Ptc EHF [2015] EWHC 72 (Pat).

² Warner-Lambert Co. v. Actavis Grp. Ptc EHF [2015] EWCA Civ 556.

³ Warner-Lambert Co. v. Actavis Grp. Ptc EHF [2015] EWHC 2548 (Pat).

⁴ Warner-Lambert Co. v. Actavis Grp. Ptc EHF [2015] EWHC 485 (Pat).