Résumé de Article 083 EPC pour la décision T0294/20 du 26.10.2023

In T 294/20, claim 1 was drafted in the form of a purpose-limited product claim pursuant to Art. 54(5) EPC and was directed to a compound for use in the treatment of nodular lymphocyte predominant Hodgkin lymphoma (NLPHL). The board stated that the Enlarged Board’s statements in G 2/21 could be seen to have endorsed the jurisprudence of the boards that attaining a claimed therapeutic effect is a limiting functional technical feature of a claim directed to the use of a substance or composition in a method of treatment. The Enlarged Board’s statements might also be understood to suggest a high standard of proof (i.e. "beyond reasonable doubt" rather than on "the balance of probabilities") which would require that the claimed therapeutic effect must, as a rule, be demonstrated in the application as filed by direct experimental evidence. However, while G 2/21 focussed on post-published evidence in the assessment of Art. 83 and 56 EPC, it did not address the question of the level of proof in an application as filed required to substantiate a therapeutic effect as a prerequisite for using post-published evidence for assessing the requirements of Art. 83 EPC. The board did not understand G 2/21 (despite its findings on the term "plausibility") to have quashed the principles established by leading decision T 609/02. As a consequence, the board found that in order to fulfil the requirements of Art 83 EPC, the suitability of the product for the claimed therapeutic application had to be derivable from the application, unless this was already known to the skilled person at the priority date (see T 609/02 and T 895/13). On how the suitability may be derived from the patent or application, the board in decision T 609/02 held: "It is required that the patent provides some information in the form of, for example, experimental tests, to the avail that the claimed compound has a direct effect on a metabolic mechanism". It had to be assessed whether the patent contained information on a direct effect of PD-1 inhibitors on a mechanism specifically involved in NLPHL. It was undisputed that the patent did not report any testing of the suitability of a PD-1 inhibitor in an animal model of cancer or in cancer cells in vitro. A central issue in this appeal concerned the information that the patent had to contain about a direct effect of PD-1 inhibition on a mechanism specifically involved in NLPHL. The appellants (patent proprietors) relied on decision T 950/13 to argue that such information might be in the form of a "plausible technical concept". However, the board considered that a "plausible technical concept" might not be stretched to include a mere hypothesis which did not need to be supported by any evidence. Instead, the board confirmed the principles developed in T 609/02 (point 9 of the Reasons). The burden to show suitability is on the applicant (G 1/03). According to the board, this burden cannot be discharged or shifted to the EPO or the public by merely alleging that a claimed therapeutic effect has to be regarded as having been demonstrated as long as not disproven. The board assessed what could be inferred from the information provided in the patent as to a direct effect of a PD-1 inhibitor on a metabolic mechanism specifically involved in NLPHL. The skilled person reading the information contained in the patent at the relevant date would not have concluded that an effect of PD-1 inhibitors on exhausted T cells was relevant to treatment of NLPHL. The board was not persuaded by the appellants' argument that the patent showed that a compound as defined in the claim was suitable for alleviating or preventing a symptom of NLPHL. As final argument put forward by the appellants was that post-published document D9 confirmed the expression of PD-L1 by the tumour cells in NLPHL. However, the board held that in a case where the patent only provides a vague indication of the suitability of the claimed compound for the therapeutic effect, post-published evidence could not be taken into account to remedy the insufficiency of disclosure. D9 therefore would indeed be the first disclosure of a possible mechanism underlying the claimed therapeutic effect.