7.2.2 Principles established by the case law – Requirement of suitability for the therapeutic effect rendered credible

The case law reported below includes the landmark decisions establishing the applicable principles and examples of decisions subsequently taken in specific cases that recapitulate and apply those principles.

The boards of appeal have recognised that in the context of the requirement of sufficiency functional features require particular attention, as such features are defined by means of an effect that has to be achievable (see G 1/03, point 2.5.2 of the Reasons, case law repeated or summed up many times cited by T 2015/20).

According to the established case law of the boards of appeal, attaining the claimed therapeutic effect is regarded as a functional technical feature of claims relating to a further medical use. In order to meet the requirement of sufficiency of disclosure of Art. 83 EPC, the therapeutic efficacy of the composition and dosage regime for the claimed therapeutic indication must therefore be credible (principle reiterated in e.g. T 421/14 (dosage regime involving twice-daily treatment – multiple sclerosis), where the claims related to a further medical use). Decision T 294/20 stated that the Enlarged Board’s statements in G 2/21 could be seen to have endorsed the jurisprudence of the boards of appeal that attaining a claimed therapeutic effect was a limiting functional technical feature of a claim directed to the use of a substance or composition in a method of treatment.

The decision in T 1959/15, in which granted claim 1 was a second medical use claim in the format of a purpose-restricted product claim pursuant to Art. 54(5) EPC, summarises the applicable approach (point 4.2 of the Reasons): According to Art. 54(5) EPC, patentability is not excluded for substances or compositions comprised in the state of the art for a specific use in a method referred to in Art. 53(c) EPC, provided that such use is not comprised in the state of the art. When a technical effect (which, in the case of a second medical use claim, is the therapeutic effect) is a feature of a claim, whether this effect is achieved by substantially all embodiments covered by the claim is a question of sufficiency of disclosure. Hence, because the subject-matter of second medical use claims is commonly limited to a known therapeutic agent for use in a new therapeutic application, it is usually only necessary that the patent renders it plausible that the known therapeutic agent (i.e. the product) is suitable for the claimed therapeutic application (i.e. the purpose: the technical effect). This decision was cited by T 3122/19 notably in relation to the issue of an alleged “reach through" claim. As for plausibility, see the findings of G 2/21 above for the current state of the law.

T 1868/16 also stated that it is established jurisprudence of the boards of appeal that, for Art. 83 EPC to be complied with, unless this is already known to the skilled person at the priority date, the application must disclose the suitability for the claimed therapeutic use (see T 609/02, point 9 of the Reasons; T 433/05, point 28 of the Reasons; T 801/06, point 25 of the Reasons). Clinical data are not always required. Mere verbal statements are however not enough. The patent application must provide some information in the form of, for example, experimental tests showing that the claimed compound has a direct effect on a metabolic mechanism specifically involved in the disease. In vitro examples may be sufficient, if for the skilled person they directly and unambiguously reflect the therapeutic application. Post-published evidence may be taken into account, but only to back up the findings in the application (see T 609/02, point 9 of the Reasons). The board in T 1868/16 considered that the application as filed did not contain any evidence that rendered the claimed therapeutic effect plausible. The effect was not derivable from the common general knowledge either. (On the issue of evidence of a therapeutic effect and the type of evidence, see also the section in this chapter II.C.7.2.3).

In T 609/02 the board pointed out that where a therapeutic application is claimed in the form allowed by the Enlarged Board in G 5/83 (OJ 1985, 64), i.e. in the form of the use of a substance or composition for the manufacture of a medicament for a defined therapeutic application, attaining the claimed therapeutic effect is a functional technical feature of the claim (see G 2/88, OJ 1990, 93, and G 6/88, OJ 1990 114, for non-medical applications). As a consequence, under Art. 83 EPC, unless this is already known to the skilled person at the priority date, the application must disclose the suitability of the product to be manufactured for the claimed therapeutic application (summaries of the points established by these decisions as regards claimed therapeutic effects can be found in, for example, T 2571/12, point 5.2 of the Reasons; T 1437/07, reported below, point 37 of the Reasons; T 421/14, point 2.3 of the Reasons; T 2015/20, which contains some very detailed and instructive findings on the point; T 395/18, point 4.3. of the Reasons; and T 899/14, points 2.4 and 2.5 of the Reasons). In decisions such as T 2181/08, T 338/10, T 1685/10, T 943/13 and T 2059/13, the boards have cited the approach taken in T 433/05 and T 609/02 and applied it to the specific cases before them.

The board in T 294/20 (rendered after G 2/21), adressing how the suitability may be derived from the patent or application, recalled relevant passages from the leading decision T 609/02, inter alia: "It is required ... the claimed compound has a direct effect on a metabolic mechanism specifically involved in the disease ...". The burden to show the suitability was on the applicant (T 294/20 quoting G 1/03, OJ 2004, 413, point 2.5.3 of the Reasons).

In G 2/21 (OJ 2023, A85) the Enlarged Board, addressing the case law related to Art. 83 EPC, first refers to T 609/02 to illustrate the applicable law and then lists a series of board decisions in line with T 609/02 (see G 2/21, points 75 and 76 of the Reasons). The Enlarged Board stressed that while the issues of sufficiency of disclosure (Art. 83 EPC) and inventive step (Art. 56 EPC) and their assessment were clearly to be treated separately and on their own, it was aware of the case law in particular concerning second medical use claims where the notion of "plausibility" had been used. In G 2/21, the Enlarged Board summarised the case law (point 74 of the Reasons) as follows. A technical effect, which, for example, in the case of a second medical use claim was usually a therapeutic effect, was a feature of the claim, so that the issue of whether it had been shown that this effect was achieved was a question of sufficiency of disclosure under Art. 83 EPC. Hence, because the subject-matter of second medical use claims is commonly limited to a known therapeutic agent for use in a new therapeutic application, it is necessary that the patent at the date of its filing renders it credible that the known therapeutic agent, i.e. the product, is suitable for the claimed therapeutic application. The legal and historical background to the patentability of further medical uses was explained in decision G 2/08. 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, does not amount to a distinctive legal concept or a specific patent law requirement under the EPC, in particular under Art. 56 EPC and Art. 83 EPC. It rather describes 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).

T 1779/21 highlighted how the principles set out in G 2/21 applies in relation to Art. 83 EPC and how they worked in the assessment of sufficiency of disclosure. In T 687/19 a referral to the Enlarged Board was requested specifically for a question in relation to post-published evidence and Art. 83 EPC. The request was rejected by the board on the basis of the law applying and citing precisely in this respect G 2/21.

The suitability of the claimed composition for the defined use needs to be disclosed in the patent, "unless this is already known". The disclosed utility of the claimed composition may thus also derive its credibility from the prior art, even if this prior art does not represent common general knowledge (T 728/21 with reference to T 609/02).

Concerning the case law relating to Art. 83 EPC after G 2/21, on the credibility requirement, the following cases, in addition to T 728/21 (credibility at the filing date was satisfied) should also be mentioned (in brackets key points addressed the decisions): T 1779/21 (not credible even taking into account the prior art); T 25/20 (no investigations or explanations, the purported mode of action merely amounted to a guess – not credible); T 1394/21 (antibodies, credible therapeutic effect on the basis of the evidence in the application as filed, the common general knowledge and the prior art); T 209/22 (credibility applied but without explicit mention of case G 2/21 – based on information provided in the application, strong presumption that dual therapy was effective and once daily dosage regime feasible – both aspects credible); T 1057/22 (credible from the information given in the application as filed that the claimed combination of fish oil and juice leads to the claimed therapeutic effects); T 2790/17 (even though experimental data were provided in the application as filed, not credible that the claimed therapeutic effect was achieved); T 197/22 (the patent did not provide the skilled person with a sufficient disclosure to generally enable the therapeutic use of the claimed formulation – general suitability was not credibly disclosed because in view of D64 (prior art) and A106 (published only shortly after priority date) serious doubts prevailed – the board was not convinced that the patent provided actual proof); T 853/22 (even accepting the argument that in a case where the technology was relatively new, the credibility of the effect could be established by relying on prior art, irrespective of whether it represented common general knowledge (T 609/02 and T 728/21), the board did not find any support in the cited prior art which rendered the claimed effect credible).

The board in T 814/12 held that it is established case law of the boards of appeal for a medical use claim to fulfil the requirements of Art. 83 EPC, unless this is already known to the skilled person at the priority date, that the patent has to disclose the suitability of the product to be manufactured for the claimed therapeutic application. A claimed therapeutic application may be proven by any kind of evidence as long as it reflects the therapeutic effect on which the therapeutic application relies (T 814/12, referring to T 609/02 in particular). In T 814/12 the board considered that by analogy the same requirements of Art. 83 EPC applied for diagnostic use claims.

In T 895/13 of 21 May 2015 date: 2015-05-21 the board stated that, pursuant to decision T 609/02, attaining the claimed therapeutic effect was a functional technical feature of a claim drawn up in the Swiss-type form. In its view, the same principle applied to purpose-related product claims drawn up in accordance with Art. 54(5) EPC. Accordingly, the therapeutic effect provided by the claimed subject-matter was to be examined in the context of the assessment of sufficiency of disclosure (Art. 83 EPC) (see G 1/03, point 2.5.2 of the Reasons) and not, as in the decision under appeal, in the context of the assessment of inventive step.

In T 1437/21, the board stated that the assessment of sufficiency of disclosure of the utility of a medicament as a requirement for patentability was to be distinguished from the assessment of a medicament for market authorisation by an agency such as the FDA as reported in document D77 submitted by the opponent in support of its allegation that the patent failed to sufficiently disclosed the suitability.

The board in T 1779/21 and T 979/23 noted that treatment by therapy did not per se necessitate the complete cure of the disease, or even the addressing of its cause, but did include the alleviation of symptoms. See also chapter I.B.4.5.1.

In T 2178/21, in relation to "functional requirement", the board detailed the distinction between claims drafted as a method claim or as a second medical use claim under Art. 54(5) EPC defining a known product for a specific new use, and as in the case at issue a product claim stating an intended use. Here the product was claimed as such and it had to be merely suitable for the intended use. The board specified that the purpose defined in the claim was not necessarily therapeutic. While hemostasis might be considered therapeutic, non-therapeutic applications were also covered.