Plausibility and the right of priority: the French court faces apixaban

One patent, the same evidence, two opposite outcomes six weeks apart. London revoked the title protecting apixaban, Paris upheld it. The comparison is instructive, because it turns not on the applicable rule but on what the court is prepared to read into the application as filed.

The same patent, two opposite outcomes

By a judgment of 4 May 2023, the Court of Appeal of England and Wales upheld the revocation of the United Kingdom part of European patent EP 1 427 415, which covers apixaban, for lack ofinventive step and insufficiency of disclosure: the application did not make plausible the inhibitory activity claimed. By a judgment of 8 June 2023, the tribunal judiciaire de Paris dismissed therévocation action brought against the French part of the same patent and against its supplementary protection certificate. The same file, two forums, two opposite results.

Plausibility according to the Paris court

The court sets aside any requirement that test results appear in the patent where the claim is to a product and not to a second medical use. It notes that the quantity of apixaban synthesised, 3.07 grams against less than one gram for the other compounds, signalled to theperson skilled in the art that the applicant regarded this compound as promising. It finally admits material outside the patent, contemporaneous with the priority date, to establish possession of the invention, in particular laboratory notebooks.

The construction is consistent with the French distinction between the requirement of disclosure and that ofnouveauté or inventive step. It nevertheless sets the threshold very low: the credibility of the technical effect is inferred from the applicant's conduct rather than from the content of the application.

Priority saved by Delaware law

The second holding went more unnoticed, it is no less consequential. The droit de priorité had arisen in the name of a subsidiary, the international application had been filed by the parent company, without any prior written cession . The court applies the law of the State of Delaware, distinguishes beneficial ownership from legal title, and upholds the priority claim for the benefit of the parent company.

Why that reading is open to criticism

Two objections deserve to be made. A plausibility threshold set too low allows an entire field of research to be reserved on the strength of an assertion, which is the opposite of the consideration expected in return for the monopoly. And relieving groups of the need to formalise their assignments weakens the readability of the chain of title, to the detriment of third parties who must work out whom they are dealing with.

Decision G 2/21 of the Enlarged Board of Appeal of theEPO, of 23 March 2023, is in fact more demanding than it appears. Post-filing evidence is not disregarded as a matter of principle, but the technical effect relied on must be one that the skilled person, on the basis of the application as filed, would derive as being encompassed by its technical teaching. That is not quite the reasoning followed in Paris.

Consequences for pharmaceutical strategies

For the originator, the lesson is documentary. What saved the patent is not the text as filed, it is the material contemporaneous with the filing: laboratory notebooks, quantities synthesised, the choice of compounds taken forward into development. That material is built in the laboratory, not in litigation. One simple discipline follows: formalise assignments within the group before any filing under priority, rather than relying on an analysis of foreign law to repair the omission.

For the generic company, an attack based solely on the absence of data in the patent is weak before the French court. It must target the technical teaching itself, the claims and the’état de la technique closest to the invention, and rely on G 2/21 rather than on a formal requirement of results. The choice of forum matters as much: before the Unified Patent Court, the validity of a medicine protected by a supplementary certificate falls, in a standalone revocation action, to the Paris seat of the central division, where the most frequent outcome to date is maintenance in amended form rather than outright revocation.

Decisions in the sector are tracked one by one in Pharma Litigation Watch and the outcomes by division in our UPC statistics. Our firm litigates these disputes before the French courts and before the UPC, in particular as correspondent in France for patents and the UPC. Contact us.

This article is an updated adaptation of an analysis by Matthieu Dhenne originally published on Kluwer Patent Blog on 25 July 2023: APIXABAN case in France: priority to the patent holder. Official sources: tribunal judiciaire de Paris, 3rd chamber 1st section, 8 June 2023, RG no. 21/12727 ; Sandoz Limited v Bristol-Myers Squibb Holdings Ireland Unlimited Company, [2023] EWCA Civ 472 ; Enlarged Board of Appeal, G 2/21, 23 March 2023.