The decisions of the Enlarged Board of Appeal of the European Patent Office and the Dutch Court of Appeal, shine light on the requirement of experimental data as evidence in patent applications. The purpose of these data is to show that a technical effect of the claimed invention, used to support inventive step, is actually achieved. In other words, to support that the invention ‘works’. In a recent case before the Enlarged Board of Appeal (decision G 2/21), the Board could only provide rather abstract criteria on whether experimental data in the application are required. The Board considered that an invention can be inventive, if the skilled person would derive from the filed application that the invention indeed works, and that this is encompassed by the technical teaching of the patent application and embodied by the same originally disclosed invention. The IP community was eager to see how this guidance would be applied in practice.

In this regard, a decision by the Dutch Court of Appeal in preliminary injunction proceedings between Bristol-Myers Squibb (BMS) and Sandoz, Stada and Teva is relevant. At the core of this case was a patent of BMS for apixaban: the active substance in Eliquis®, a medicament that is used as a blood thinner in the treatment of thromboembolic disorders. Apixaban works via inhibition of an enzyme called factor Xa.

Martin Klok, partner and European patent attorney at V.O., assisted Hogan Lovells on the side of BMS in this case: “The question for the Court of Appeal was whether the patent application contained enough information to derive whether apixaban was the most promising factor Xa inhibitor in the application, i.e. that apixaban would ‘work’ best. Even though the application did not provide all data, the Court ruled that enough information was disclosed. With this ruling, later filed experimental evidence could be used by BMS to further show the improved factor Xa inhibitory activity. On this basis, the Court concluded that the patent was inventive. Sandoz, Stada and Teva were ordered to cease their infringing commercialization of apixaban.”

When it comes to the necessity of having experimental data in a patent application at the time of filing, decision G 2/21 gives diverse requirements. For patent applications and patents that recite a technical effect in the claim (for example in particular medical use inventions of a pharmaceutical compound), the requirement is stricter than for claims which recite only a product, without mentioning the intended medical use. For such medical use inventions, experimental evidence seems necessary, in particular when without such data, the medical use would not be credible. The Dutch Court of Appeal in the Apixaban case has followed this guidance in its decision.

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