The European Patent Office (EPO) has a notoriously strict approach to assessing added matter according to Article 123(2) EPC. In the recent decision T 2842/18, the EPO’s Technical Board of Appeal 3.3.04 scrutinised the basis for a therapeutic effect in a second medical use claim. The decision demonstrates that speculative language can undermine a verbatim statement of a therapeutic effect in the application as filed.According to Article 123(2) EPC, a European patent application or European patent may not be amended in such a way that it contains subject matter which extends beyond the content of the application as filed. Established case law sets out the ‘gold standard’ for assessing added subject matter according to Article 123(2) EPC: the claimed subject matter must be directly and unambiguously derivable from the application as filed. After the amendment, the skilled person may not be presented with new technical information.In T 2842/18, the claim in question had been amended to include the medical use “for preventing or slowing down the progression in structural joint damage and erosion caused by rheumatoid arthritis”. The question was whether this effect could be directly and unambiguously derived from the application as filed.The Opposition Division had previously held that the requirements of Article 123(2) EPC were met because the therapeutic effect was disclosed verbatim in Example 3 of the application as filed: “It is expected that re-treatment under the protocol herein […] will be effective in preventing or slowing down the progression in structural joint damage and erosion caused by RA”.However, the Board took a more stringent approach, and considered whether the skilled person could directly and unambiguously determine that the effect of “preventing or slowing down the progression in structural joint damage and erosion” would be achieved when carrying out the claimed treatment. In view of the speculative language “it is expected”, the Board held that the skilled person would only derive from the statement that the “effect might or might not be achieved. The skilled person would not conclude that the effect was definitely achieved” (see point 48 of the Reasons).The Board went on to consider the teaching conveyed by Example 3 as a whole. It was deemed that Example 3 contained further uncertainties as to whether the claimed therapeutic effect was achievable, which only confirmed that the above statement was merely expressing a speculation. The uncertainties pointed to by the Board (in points 48-49 of the Reasons) included Example 3 being a protocol for a proposed clinical study that had yet to be carried out, and the objective of the study being to “evaluate the efficacy” to “potentially prevent disease progression“.On this basis, the Board concluded that the effect could not be derived from the application as filed, and so the claim extended beyond the content of the application as filed.It is important to the note that the Board emphasised that this was not a question of enablement, noting that the “criteria for the assessment of direct and unambiguous disclosure of a claimed therapeutic effect are independent of, for example, the presence of data or the assessment of plausibility of the claimed effect”. Instead, the question was whether the effect could be derived from the application as filed in view of the phrase “it is expected” (see points 54-57 of the Reasons).A significant parallel can be drawn with the case law, noted in our recent article, on the novelty of medical use claims over prior art indicating that a clinical trial for a candidate treatment is underway but results are not yet reported. Such disclosures are deemed not to anticipate a medical use claim directed to the candidate treatment because the skilled person is not able to discern from the prior art whether the therapeutic effect can actually be achieved. For example, in T 715/03, the Board stated:“The fact that phase II studies are running also means that phase I studies are concluded. However, from this information the skilled person can only conclude that the results on safety and tolerability in humans, as well as the pharmacokinetics studies, were positive. However, there is no information about a possible beneficial effect on TS patients.”More recently, T 1859/08 confirmed that “a mere statement that a […] therapy is being explored does not amount to a novelty-destroying disclosure” of a medical use claim.Thus, even when a candidate treatment is deemed to be so promising that it is revealed to be undergoing clinical evaluation, that per se does not disclose the medical use of the relevant substance in treating the relevant patients. Vital information is missing – i.e. whether or not the treatment is actually effective.Indeed, in T 1437/07, the Board explained that the teaching in the prior art “was considered as speculative or hypothetical because it was not clearly and unambiguously derivable” that a particular therapeutic effect had been achieved. Again, this was not a question of enablement, but rather a question of information content. In the absence of a concrete statement of “treatment”, the prior art could not be interpreted as disclosing the claimed subject matter.Significantly, however, the Board held in T 1437/07 that a hypothetical embodiment could provide basis for an amendment. It was not relevant to Article 123(2) EPC whether the disclosure had in fact been carried out it, but rather whether it was possible to derive, directly and unambiguously, the effect from the written disclosure as a whole.Therefore, the Board’s judgment in T 2842/18 aligns the standards of disclosure for added matter and novelty of medical use claims.OutlookIn summary, T 2842/18 highlights that hypothetical or conditional language, reflecting a more cautious approach commonly used in scientific literature, can risk reducing a disclosure of a therapeutic effect to a mere suggestion. If such language is present in the examples, it appears necessary to include more concrete statements in the description or claims on filing to ensure adequate basis for the therapeutic effect is provided.