30/04/2026
This year, there were a large number of changes to the EPO guidelines that relate specifically to the life sciences sector, and particularly to clinical stage patent applications. The new guidelines now include updates relating to the sufficiency of medical use claims, when the novelty of a medical use claim is affected by clinical trial disclosures, novelty based on patient groups, novelty of medical uses including mechanistic features, and exceptions to patentability.
Many, if not all of these changes, codify existing practice and reflect the established position of the Technical Boards of Appeal; however, their inclusion in the guidelines is notable nonetheless. We discuss these in more detail below.
Nick Reeve recently reported on the EPO guideline changes more generally in his article here.
Sufficiency: Medical use claims
The requirement that a European Patent application discloses an invention sufficiently and completely so that it can be carried out by a person skilled in the art is recited in Article 83 EPC. The guidelines provide further information on what this means and the update this year focusses on what this means for medical use claims.
Part F, Chapter III, of the guidelines has been updated to include a new section on how sufficiency of further medical use claims should be assessed. The new section is copied below.
“In a further medical use claim, the claimed therapeutic effect is a functional technical feature of the claim, i.e. the claims are commonly limited to a known substance or composition for use in a new therapeutic application (G-VI, 6.1).
In order to meet the requirements of Art. 83, the proof of a claimed therapeutic effect has to be provided in the application as filed, in particular if, in the absence of experimental data in the application as filed, it would not be credible to the skilled person that the therapeutic effect is achieved. An insufficiency in this respect cannot be remedied by post-published evidence (G 2/21).
It is therefore necessary that, at the date of filing, the application render it credible that the known substance or composition is suitable for the claimed therapeutic application and that the therapeutic effect arises as a result of the therapeutic measures defined in the claims. Mere verbal statements are not sufficient to render the therapeutic effect credible. The application as filed must provide either suitable evidence in which the therapeutic effect is demonstrated or scientific reasoning based on known effects for the claimed substance or composition. While it is not necessary for every conceivable treatment falling within the scope of the claims to be therapeutically effective, an undue amount of research should not be needed for the skilled person to arrive at therapeutically effective treatments.”
This new wording sets out the established approach of the EPO. The guidelines confirm that the claimed therapeutic effect is a functional technical feature of the claim. This means that at the date of filing, the application must render it credible that the substance attains the claimed therapeutic effect. The application must provide either data to demonstrate the effect, or reasoning, such as a physiological mechanism, for why the claimed substance has the claimed effect. Importantly, as set out in G2/21, this type of insufficiency cannot be remedied by post published evidence.
While data demonstrating the therapeutic effect in the specification is not necessarily required to render a medical use claim sufficient, including such data is always going to be the safest option. In an ideal world this would be data from a clinical study; however, animal data or even in vitro data may be enough in some cases.
Medical use claim in which the pharmaceutical Agent is defined functionally
The new guidelines also set out further requirements that must be met when the substance is defined functionally. The guidelines set out the following:
“A claim directed to a further medical use wherein the active pharmaceutical agent is defined only in terms of functional features meets the requirements of Art. 83 if all of the following conditions are met:
(a) specific compounds achieving the claimed function are part of common general knowledge or are known from the prior art or are disclosed in the application as filed in such a way that it is credible that the compounds achieve the claimed function;
(b) the claimed function can be verified by tests or procedures which are adequately specified in the description or known to the skilled person and which do not require undue experimentation; and
(c) the application as filed shows that the claimed function is causal for the solution of the problem underlying the invention, such that it is credible that any compound achieving the claimed function is suitable for the claimed therapeutic application.”
This update explains that it must be credible that the functionally defined compound actually achieves the claimed function. This could be based on the description in the specification or potentially based on information in the prior art.
The skilled person must also know how to verify the claimed function by a test or other procedure either by information included in the description or potentially information that would form the common general knowledge of the skilled person.
Finally, the update sets out that the application as originally filed must show that the claimed function relates to the problem underlying the invention, such that it is credible that any compound achieving the claimed function would also be suitable for achieving the claimed therapeutic effect.
Exceptions to patentability
The guidelines include an update in view of T775/97 relating to a specific situation in which a product claim falls within the exception of Article 53(c) EPC.
This update relates to a niche but interesting situation where a claimed product is defined such that surgical steps are required to form the product itself. In the case of T775/97, a bilateral surgical bypass graft was defined as being obtained following steps which were deemed by the Technical Board of Appeal to be surgical in nature. In such a situation, the exception to patentability under Article 53(c) would apply.
Novelty: Selection inventions relating to numerical ranges
It is not uncommon for claims to inventions in the chemistry, materials and life sciences space to be defined by a numerical range. For example, this could be a range in an amount of a component making up a composition or a range in a parameter such as tensile strength or blood plasma concentration.
The guidelines have been updated to confirm that when assessing the novelty of a subrange of numerical values selected from a broader numerical range disclosed in the prior art, the test that should be applied is whether the claimed range is directly and unambiguously derivable from the prior art.
The old approach included in previous versions of the Guidelines specified that the selected subrange must be narrow and sufficiently far removed from the disclosure of the prior art. This has now been deleted. Additionally, the previously included concept of “seriously contemplating” has also been removed.
The guidelines have now been updated in line with T1688/20 to make it clear that the gold standard test for assessing novelty should also be applied when considering a selection invention involving a numerical range. This brings consistency and clarity to the assessment of selection inventions at the EPO.
Clinical trial publications
Part G, Chapter VI has been updated to include a new section on when a disclosure can destroy the novelty of a medical use. The new section has clinical trial publications in mind, but the approach would apply to all types of disclosure.
“A document is prejudicial to the novelty of a claim directed to a specific further medical use if it
i. clearly identifies the essential conceptual features of the therapeutic treatment, i.e. the substance/composition used for treating the medical indication and any essential features of the treatment; and
ii. plausibly establishes the underlying therapeutic effect. Plausibility may be established by way of data or scientific reasoning. It is not however necessary that the mechanism underlying the therapeutic effect be explained. […]”
This update sets out the approach that should be taken when assessing the novelty of a further medical use claim. The second step listed above is of particular note, setting out that the document must plausibly establish the underlying therapeutic effect in order for a disclosed use to be novelty destroying. For example, this could mean that a document merely announcing a clinical trial of a drug for treating a particular disease would not itself necessarily prejudice the novelty of a medical use claim directed to the same drug for use in treating the same disease.
This update seems broadly to follow the approach taken by the Boards of Appeal, although there may be differing approaches to how step ii is assessed, and the guidelines do not provide any further guidance on how high the plausibility hurdle should be.
Medical use claims limited by patient Group
The guidelines also add a further new section on medical use claims that are directed to treatment of a specific group of patients. This new section introduces the well established approach to the novelty of patient groups taken by the Technical Boards of Appeal.
Before the EPO, it is possible for a medical use claim to be distinguished over the prior art solely by virtue of the treatment being directed to a novel group of patients. The patient group could be defined by a particular characteristic, such as the level of a biomarker or age. As set out below, the guidelines describe two ways in which a patient group can be defined – passively and actively.
“6.1.2.2 Patient group
The treatment of a known clinical indication in a different patient group for example characterised by age, gender, weight, physiological parameters or a biomarker may represent a new specific use under Art. 54(5) EPC.
The selection of the patient group may be defined
- in passive terms where the group characteristic is defined (e.g. “being at least X years of age”, “expressing gene X” “having mutation Y in gene X”) or
- in active terms where the step of determination/selection is explicitly defined as an essential feature of the claim (e.g. “comprising a determination of mutation Y in gene X and selecting a patient having said mutation”). […]”
In the passive definition, the group is defined in the claim as having a particular characteristic, e.g. “wherein the patient has a blood serum calcium level greater than 2.6 mmol/L”. For a passively defined patient group, novelty is established if the patient group does not overlap with a previously treated group, or if the patient group is a specific subgroup which has not been identified in the prior art in the context of the claimed therapy.
An active definition would require a step of determining the characteristic that defines the patient group. For example, following the example above, the claim would recite a step of measuring the blood serum calcium level. In the case of an actively defined patient group, novelty is established if the specified step of determining the characteristic defining the patient group has not previously been disclosed in the context of the claimed therapy.
While this update mirrors the approach of the Boards of Appeal, the update provides clear guidance for examiners and provides a useful resource to reference during examination if needed.
Medical uses defined by mechanistic features
The guidelines also include a new section dealing with medical use claims that are defined by a mechanism or mode of action.
The guidelines have been updated to specify that a medical use claim can be distinguished by mechanistic features relating to a mode of action underlying a therapy; however, if the mechanism is the only difference between the claimed invention and the prior art, the mechanism should not merely be an explanation of a mechanism underlying a known therapeutic use.
In other words, including mechanistic steps underlying the treatment, such as binding of the drug to a receptor, will not necessarily confer novelty. Further, the update stresses that a mere pharmaceutical effect does not necessarily imply a therapeutic application. For example, the selective occupation of a specific receptor by a substance cannot be considered itself to be a therapeutic application. Again, this addition to the EPO guidelines broadly mirrors the established approach taken by the Technical Board of Appeal.
Conclusion
The changes to the guidelines detailed above are not in themselves controversial. These reflect established jurisprudence of the Technical Boards of Appeal. However, their inclusion in the new version of the guidelines is significant and perhaps suggests areas of developed case law.
This content is for general information only. Its content is not a statement of the law on any subject and does not constitute advice. Please contact Reddie & Grose LLP for advice before taking any action in reliance on it.
