The Supreme Court of the United Kingdom has now released their long-awaited decision relating to the tests for sufficiency and infringement for second medical use patents, in particular those with so-called “Swiss-form” claims – Judgment here. Swiss-form pharmaceutical patent claims are purpose limited process claims, commonly in the form “the use of compound X in the manufacture of a medicament for the treatment of indication Y”.
In declaring Warner-Lambert’s patent invalid for lack of sufficiency, and not-infringed had it been valid, some clarity in respect of sufficiency has emerged, though a definitive test for infringement of such a patent is still lurking in the shadows.
Warner-Lambert is part of the Pfizer group of companies and are the proprietor of now-expired European Patent No EP0641330 for Isobutylgaba, which describes the use of Isobuylgaba for the treatment of seizure disorders such as epilepsy. The commercial product Pregabalin, which is a derivative compound of Isobutylgaba, is marketed by Warner-Lambert under the “Lyrica” brand. A further second medical use patent EP(UK)0934061 claims the use of pregabalin for treating, in particular, pain, inflammatory pain and neuropathic pain. The claims of this second medical use patent are in the Swiss-form. Lyrica has marketing authorisation in the EU for treatment of peripheral and central neuropathic pain, also in addition to the original indications of epilepsy and generalised anxiety disorder. It is one of Pfizer’s most successful drugs. Actavis markets a generic pregabalin product under the brand name “Lecaent”.
At the Supreme Court Actavis and Mylan argued that the second medical use patent should be revoked for insufficiency. Warner-Lambert on the other hand claimed that Actavis infringed Claims 1 and 3.
Claims 1 (pain) and Claim 3 (neuropathic pain) were held invalid at first instance because Claim 1 was construed as extending to all pain and Claim 3 was construed to extend to all neuropathic pain. In addition, it was found that there was only sufficient disclosure in the specification to indicate plausible efficacy for the treatment of inflammatory and peripheral neuropathic pain, i.e. not central neuropathic pain. Since the specification was not sufficient across the breadth of the claims they were held invalid. Furthermore, it was held that had they been sufficient, the claims would not have been infringed. These findings were upheld at the Court of Appeal.
The Supreme Court was required to look at the issues of sufficiency and infringement in the context of second medical use patents. In particular, the Supreme Court needed to address the developing law of plausibility of patent claims in the context of sufficiency and address what, if any, threshold needs to be met for plausibility and whether post filed data could render an invention plausible.
Claim Construction and Post-Trial Amendments
On the issue of claim construction, the Supreme Court unanimously agreed with the courts below that the claims to pain and to neuropathic pain extended to all types of pain and all types of neuropathic pain respectively. It also unanimously affirmed the UK legal position that seeking an amendment of a patent post trial is an abuse of process. This prevented Warner-Lambert narrowing its claims post-trial to peripheral neuropathic pain, for which there was support.
The Supreme Court concluded (though not with complete agreement as to the approach), that the patent was invalid for lack of sufficiency.
Insufficiency of Second Medical Use Patents
By a majority decision (from three of the five Supreme Court Judges, Lords Sumption, Reed and Briggs) it was held that for second medical use patents a patentee is required to demonstrate that the specification discloses some scientific reason why the implied assertion of efficacy in the patent claim is true. Whilst experimental data may not be the only acceptable evidence, a bare assertion or mere possibility of therapeutic efficiency is not enough. The rationale for this, especially in relation to second medical use patents where the invention is for the new use of something that is already known, is that there is the need to prevent speculative patenting. A monopoly is only justifiable if the patent itself discloses with some substance, a contribution to the art.
Therefore, whilst the disclosure in the specification supported claims in relation to inflammatory pain, there was no support in the patent making the invention plausible for neuropathic pain, whether peripheral or central.
There was dissent from two Judges (Lords Mance and Hodge) who preferred a lower standard of plausibility believing that that the majority’s approach imposed too high a threshold.
Avoiding Infringement of Second Medical Use Patents
The Supreme Court continued to consider whether the claims would have been infringed had they been valid as it recognised that this is an important area of law in relation to second medical use patents. The Supreme Court unanimously held that if Claims 1 and 3 had been valid, they would not have been infringed, however, the rationale for this diverged significantly.
Two Judges (Lords Sumption and Reed) considered that the intention of the alleged infringer, whether subjective or objective, is irrelevant. They preferred relying on the sole question of whether the final product, including the label and instruction leaflet is presented as being suitable for the patented uses – the “outward presentation” test. A third (Lord Mance) agreed that the test should depend on the objective appearance and characteristics of the product as it is prepared, presented and put on the market. However, he took the view that in some cases the wider context may suggest that the outward presentation should not to be taken at face value and that there could be circumstances in which a generic manufacturer would need to positively exclude certain uses.
The other two Judges (Lords Briggs and Hodge) on the other hand preferred the test, which was adopted at first instance by Arnold J, as to whether the alleged infringer subjectively intended to target the patent-protected market.
How to make a Second Medical Use Patent Plausible
The decision on sufficiency provides some greater clarity on the lengths required by patentees to support their claims. The relevant test appears to be not whether the invention is plausible, but whether the patent specification discloses something that would make it plausible in the eyes of the skilled reader. Whilst it need not be necessarily demonstrated by data, at the very least some scientific reason supporting the claims must be contained in the specification of the patent for the invention to be plausibly and sufficiently disclosed in the patent.
How to avoid infringement of a Second Medial Use Patent
It is impossible to take a definitive test on infringement from this Judgment, but at the same time, it does provide a helpful guide to generic companies wishing to market their drug for an out of patent use. To be safe, it would appear necessary, at least for now, to satisfy the “outward presentation” test (i.e. ensure that the final product is not presented as being suitable for the patent-protected market), and for there to be no subjective intention to target the patent-protected market.
It would therefore be important for generic manufacturers wishing to avoid a second medical use patent to ensure that the formation, dosage, packaging, labelling and patient information leaflet for its drug are all such that they are not directed to the patented indication.
In summary, the final word of the Judgment sums up neatly where the Supreme Court got to: “The protection afforded by a Swiss-form patent, analysed as protecting a process in the way that English law analyses it, is valuable, but necessarily limited”.