7.2.3 Evidence of therapeutic effect
Without negating the solutions reached by numerous decisions in the earlier case law, cited in particular in G 2/21 itself, the Enlarged Board in G 2/21 departed from the concept of "plausibility". It held that the term "plausibility" that is found in the case law of the boards of appeal and relied upon by the referring board (T 116/18 of 11 October 2021 date: 2021-10-11) did not amount to a distinctive legal concept or a specific patent law requirement under the EPC, in particular under Art. 56 and 83 EPC. It rather described a generic catchword seized in the jurisprudence of the boards of appeal, by some national courts and by users of the European patent system (point 92 of the Reasons).
The case law prior to G 2/21 often referred to the notion of plausibility, and it was frequently noted that if a therapeutic application is to be accepted as sufficiently disclosed, the application or the patent, respectively, and/or the common general knowledge has to provide some information rendering it technically plausible for the skilled person that the claimed compounds can be applied for the claimed therapeutic use (T 1599/06 citing T 609/02).
In relation to a novelty issue, the board in T 1437/07 (Botulinum toxin) held that a disclosure in a prior art document is novelty-destroying only if the teaching it contains is reproducible. It held that this need for an enabling disclosure was in conformity with the principle expressed in Art. 83 EPC. Thus, the requirements of sufficiency of disclosure are identical for a prior art document and a patent. In this context, with reference to the principles set out in T 609/02 (point 9 of the Reasons), it concluded that the main claim lacked novelty over prior art document R21. Moving on to the objection under Art. 83 EPC for an auxiliary request, the board in T 1437/07 reiterated that the requirement of sufficiency of disclosure is considered to be fulfilled with respect to a claim to a second medical use if the disclosure in the patent or the common general knowledge enables the skilled person to obtain the compound to be applied and to apply it, and if there is evidence that the intended therapeutic effect can be achieved. The board in that case also stated that just because a patent disclosed an effect which had not in reality been achieved, there was no reason – in the absence of convincing evidence that the effect could not be achieved – for it to doubt that the effect could be achieved (point 38.1 of the Reasons).
The board in T 899/14 decided that, contrary to the view taken by the appellant (patent proprietor), it was not sufficient merely to describe an administration regimen to be followed, without any evidence of the therapeutic efficacy of the proposed treatment. The appellant had not argued that it was common general knowledge but instead relied on the examples. The question was thus whether the information presented in the examples could render the alleged efficacy credible, or at least establish its initial plausibility. The board also noted that while results of clinical trials or animal studies were not always necessary to establish sufficiency of disclosure, a mere verbal statement in the application was not enough to establish even the initial plausibility of an alleged therapeutic benefit.
Having reiterated the applicable principles (point 4.2 of the Reasons), the board in T 1959/15, where granted claim 1 was a second medical use claim in the format of a purpose-restricted product claim pursuant to Art. 54(5) EPC, found that the patent in this specific case, besides amounting to an invitation to perform a research programme and thus an undue burden, showed an effect (on cardiomyopathy) for only two exemplary compounds having the desired capability. Since these two compounds were structurally very similar, it was not plausible that all possible (structurally distinct) compounds having this capability would have the same effect.