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 (see T 814/12). In T 814/12 the board considered that by analogy the same requirements of Art. 83 EPC applied for diagnostic use claims.

In T 609/02 the board pointed out that where a therapeutic application is claimed in the form allowed by the Enlarged Board of Appeal 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, and T 1437/07, reported below, point 37 of the Reasons).

The requirement of sufficiency of disclosure is considered as 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 (T 1437/07 – Botulinum toxin).

Either the application must provide suitable evidence for the claimed therapeutic effect or it must be derivable from the prior art or common general knowledge. The disclosure of experimental results in the application is not always required to establish sufficiency, in particular if the application discloses a plausible technical concept and there are no substantiated doubts that the claimed concept can be put into practice (T 950/13 citing T 578/06).

Any kind of experimental data have been accepted by the boards. It has also been repeatedly emphasised that "it is not always necessary that results of applying the claimed composition in clinical trials, or at least to animals are reported" (T 1273/09 citing T 609/02).

If the description in a patent specification provides no more than a vague indication of a possible medical use for a chemical compound yet to be identified, more detailed evidence cannot be used later to remedy the fundamental insufficiency of disclosure of such subject-matter (T 609/02). Where the therapeutic effect is a functional technical feature of the claim, the application must disclose the suitability of the product to be manufactured for the claimed therapeutic application and evidence filed later cannot be used to remedy a fundamental insufficiency of disclosure (point established in T 609/02, as summarised in T 1045/13).

Referring to T 609/02, the board in T 433/05 recalled that where a therapeutic application was claimed in the Swiss-type form, attaining the claimed therapeutic effect was a functional technical feature of the claim. As a consequence, under Art. 83 EPC 1973 the application had to disclose the suitability of the product to be manufactured for the claimed therapeutic application (see also T 1685/10). Note, however, that according to G 2/08 date: 2010-02-19 (OJ 2010, 456), where the subject matter of a claim is rendered novel only by a new therapeutic use of a medicament, such claim may no longer have the format of a so-called Swiss-type claim as instituted by decision G 5/83 (OJ 1985, 64). Following T 609/02, the board in T 801/06 recalled that a claimed therapeutic effect may be proven by any kind of data as long as they clearly and unambiguously reflect the therapeutic effect. Thus, the fact per se that the experiments in the patent were not carried out with a "real" metastasis was not sufficient to deny sufficiency of disclosure.

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).

Post-published evidence may be taken into account, but only to back-up the findings in the application in relation to the use of the compound(s) as a pharmaceutical (T 609/02, T 950/13).

These principles were applied to decisions concerning second medical use claims (see, for example, T 699/06 and T 1396/06) and in T 604/04, to claims directed to first medical use claims and to pharmaceutical compositions.

In T 1777/12 claims 1 and 10 were medical use claims and related to the use of a PYY agonist in the manufacture of a medicament for treating a metabolic disorder in an obese or overweight subject. Clinical trials are not required to establish suitability. It may suffice that in vitro or in vivo data directly and unambiguously reflect the therapeutic effect on which the claimed therapeutic application relies or, alternatively, that there is an established relationship between the physiological activities of the compound under consideration and the disease in question. The board concluded that the disclosure in the patent demonstrated the suitability of PYY for achieving a beneficial effect in all of the claimed therapeutic applications by reducing weight or weight gain.

In T 1045/13, concerning a second medical use claim worded in accordance with Art. 54(5) EPC, the board stated that the application as filed did not provide any indication of the principle underlying the relationship between the activity of the pharmaceutically active agent, i.e. the NGF, and the therapeutic effect, i.e. the alleviation of the symptoms of the psychological conditions claimed. The description did not provide any information on the mechanism of action of NGF. No background references were cited that linked NGF to the therapeutic effects to be obtained, and no in vitro assays were provided to illustrate any such effect. In the complete absence of such information, the experimental evidence on file was of decisive importance. But the evidence in the application as filed did not constitute a sufficient disclosure. Indeed the experimental evidence consisted of eleven examples relating to various conditions but did not cover all the conditions defined in claim 1; each example related to a single patient only, contrary to the common practice in order to allow statistical analysis of the results. Also, in the absence of a control group, placebo effects could not be excluded. The post-published evidence might be taken into account, but only to back up the findings in the patent application. Post-published evidence could not establish sufficiency of disclosure on its own. They did not need therefore to be discussed.

For sufficiency of disclosure, it is not relevant what the respondent (patent proprietor) was aware of, but decided not to disclose. Rather the application, taking into account common general knowledge, must contain sufficient evidence or at least a technically plausible concept that allowed the skilled person to conclude that the claimed compound is suitable for the claimed therapeutic use. The board agreed with the statements made in T 433/05 and T 801/06 referred to by the respondent, but in case T 1868/16, no data or plausible technical concept was present in the patent. Reference was also made to T 609/02 and T 801/10, but in the present case no effect was observed (T 1868/16 – suitability of everolismus in the treatment of PNETs).

A post-published document reporting that no proven effective vaccine against HSV was available did not prove the non-workability of the invented vaccine, since there might have been other reasons, e.g. regulatory reasons, for not producing vaccines according to the invention. Furthermore, for compliance with the requirements of Art. 83 EPC 1973, it was not necessary to undertake and disclose clinical trials (T 1023/02).

In T 2571/12 (treatment of schizophrenia with glutathione), the board stated that there was no evidence at all either in the patent or in the available prior art for a therapeutic effect of glutathione precursors for any of the claimed disorders, and hence the post-published document, allegedly supporting such an effect inter alia for bipolar disorders, likewise could not been taken into account for the assessment of sufficiency of disclosure.

For the acceptance of sufficient disclosure of a therapeutic application, it is not always necessary for results of clinical trials to be provided at the relevant date, but the patent/patent application must provide some information showing that the claimed compound has a direct effect on a metabolic mechanism specifically involved in the disease. Once this evidence is available from the patent/patent application, post-published evidence may be taken into account to support the disclosure in the patent application (T 433/05).

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. 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 1616/09 the board pointed out that, for the purposes of Art. 83 EPC, the level of disclosure in the application which is required for claims directed to pharmaceutical compositions or kits is not the same as that which is required for medical-use claims. For claims directed to pharmaceutical compositions or kits it is in principle sufficient that the application provides information which allows the skilled person to produce the composition or kit, and that there are no substantiated doubts that it could indeed be used in therapy. For second-medical-use claims, on the other hand, it is required not only that the composition itself is disclosed in an enabling way but also that its suitability for the claimed treatment is plausibly disclosed in the application. In the case of a claim directed to a pharmaceutical composition comprising two classes of compounds which had both already been used in therapy in the prior art, there was a priori no reason to doubt that such a pharmaceutical composition could be produced; no specific functional effect had to be demonstrated. In the case of second-medical-use claims, if the claimed therapeutic effect was already known to the skilled person at the priority date, it was not necessary to demonstrate it in the application. According to T 1616/09, T 609/02 does not apply to compositions but only to second-medical-use-claims (see also T 1592/12, which also states that it is not sufficient to show that the skilled person can apply the claimed dosage regime, points 16-17 of the Reasons).

In T 1823/11 claim 1 related to phaseolamin for use as an anticaries agent. In its decision to refuse the application for non-compliance with the requirements of Art. 83 EPC, the examining division had pointed out two deficiencies, namely the absence of indications as to the preparation of phaseolamin and the absence of any information as to the pH conditions. The board did not share this conclusion. It decided to remit the case and addressed some observations to the first-instance department. It observed that claim 1 was drafted as a purpose-limited product claim in accordance with Art. 54(5) EPC. The technical effect of phaseolamin of being useful as an anticaries agent was expressed in the claim. When the technical effect was expressed in the claim, the issue as to whether this effect was indeed achieved over the whole scope of the claim was a question of sufficiency of disclosure (G 1/03, OJ 2004, 413, point 2.5.2 of the Reasons). This general approach applied in particular to claims including a therapeutic effect as a feature of the claim, such as purpose-limited product claims in accordance with Art. 54(4) and 54(5) EPC or claims drafted in accordance with the "Swiss-type" format (T 906/10, T 1616/09, T 1869/11). Thus, in order to establish whether the requirement of sufficiency of disclosure was met it had to be assessed at first instance whether the application disclosed the potential suitability of phaseolamin to act as an anticaries agent or whether this information could be derived from the prior art.

T 338/10 concerned a claim for a second therapeutic use in which the active ingredient was a "first allergen" and the therapeutic use the treatment or prevention of an allergy caused by a different, second allergen. The board found that there was no experimental data in the patent proving that a first allergen could be used to treat an allergy caused by a different allergen.