Implausibly incredible or just plain insufficient?

Warner-Lambert is a subsidiary of pharma giant Pfizer and it has a patent for a drug called pregabalin, sold under the trade mark Lyrica. The patent was the subject of a decision of Mr Justice Arnold [2015] EWHC 2548 (Pat), which the Kats pawed over here. His decision was upheld by the Court of Appeal in Warner-Lambert v. Actavis and Generics [2016] EWCA Civ 1006, unravelled by the Kats here. 

The case touched on a number of issues, both substantive and procedural, but the one of most interest to this GuestKat is the decision on insufficiency, based on which several claims of the patent were held invalid. As a result, Pfizer will not have patent protection for Lyrica in respect of its use as a treatment for certain types of pain, because it was found that there was no basis for saying that it was "plausible" that pregabalin would be effective for all types of pain. Against that background, the patentees have appealed to the UK Supreme Court, which has agreed to hear the case. The main issue before the Supreme Court is whether “plausibility” should play a role in the statutory test for sufficiency of disclosure. 

This GuestKat has had his claws in patent law for a long time, but does not remember reading the word “plausible” in the EPC or the Patents Act 1977.  So where has it come from? The Court of Appeal judgment refers back to Regeneron v. Genentech [2013] EWCA Civ 93 [2013] RPC 28, in which it was said that this requirement originated in the jurisprudence of the Boards of Appeal of the EPO, following from the decision in T 939/92 Agrevo/Triazole herbicides. As Mr Justice Arnold explains in his decision, there are two types of insufficiency according to the case law: “classical insufficiency”, which means failure to enable the invention to be performed without undue burden, and “Biogen  insufficiency” (named after Biogen v Medeva [1997] RPC 1), which is a failure to enable the invention to be performed over the whole scope of the claim.

Lord Justice Kitchin in Regeneron said that it must be possible to make a reasonable prediction that the invention will work with substantially everything falling within the scope of the claim or, "put another way", the assertion that the invention will work across the scope of the claim must be "plausible or credible". Another way of characterising this type of objection is as a matter of “excessive claim breadth”, although this is not an express ground on which a patent can be revoked.

The crux of the matter, looking at it in the context of chemical inventions, is that you can’t just make up a generic formula that covers a wide range of compounds and leave it to the imagination or later investigation to see if some or all of those compounds might be in some way useful.  Lord Justice Floyd in the Court of Appeal in the present case said one could draw the conclusion from the cases that a mere assertion that compound X is suitable for treating disease Y is not sufficient without more to render the invention “plausible”.  

A related issue, looking at things from the point of view of inventive step, is whether something is “obvious to try”. Here, "a reasonable expectation of success" is required, which Mr Justice Henry Carr in Actavis v. Lilly [2015] EWHC 3294 (Pat) ruled should not be equated with "plausibility."  He said the latter is a threshold test, which asks just if the invention is "credible", based on the patent and common general knowledge. This GuestKat thinks a definition in terms of another word - "credible" - doesn't really help here, especially when the two words seem to have been used interchangeably in Regeneron, but the point seems clear that "plausibility" is not to be elevated to the status of an additional criterion for patentability.

A patent can only be found invalid based on specific grounds, and the relevant one here is that the specification does not disclose the invention clearly and completely enough for it to be performed by a person skilled in the art. If such a person can’t tell from the information provided in the patent whether or which parts of the invention will or won’t work, then that requirement is not met and the patent will be invalid. 

This GuestKat wonders whether it is right to introduce additional words and concepts into the assessment of validity, such as “plausibility” and “credible”, which are not to be found in the statute or the convention. The danger is then that they take on a significance of their own. Thus, in this case, the Supreme Court is being asked to address the question "whether (and what) role plausibility should play in the statutory test for sufficiency, and whether a patent should be held insufficient for lack of plausibility even though it is in fact enabled across the full scope of the claim".  This GuestKat awaits the judgment with interest.