Substance or device? Decoding medical use claims under the European Patent Convention

Medical therapies do not include only drugs, and devices are an important part of the therapeutic arsenal, as well as in diagnostics. The medical technology sector has seen rapid expansion in recent years, driven at least in part by the rise of AI and its integration into diagnostic, monitoring, and therapeutic devices. There is therefore a growing need to protect medical devices, including new medical uses of known products.

In Europe, it is not possible to patent methods of treatment of the human or animal body by therapy or surgery (Article 53(c) EPC). However, the European Patent Convention (EPC) does provide protection for substances and compositions for use in methods of treatment in the form of so-called “medical use” and “second medical use” claims (Article 54(4) and (5) EPC). These types of claims (referred to collectively here as “medical use claims”) are purpose-limited product claims, and it is the recited use, not the product itself, which provides novelty and inventive step. This means that examination of medical use claims usually focuses on whether the recited use is novel and has an inventive step. However, there is usually less focus on the other criterion for medical use claims, namely that the product in question must, specifically, be a “substance or composition”. 

It has long been established that Article 54(4) and (5) EPC does not permit devices to be the subject of a medical use claim, such that a new medical use of a known device is not patentable in Europe. However, the EPC does not define a “substance” or a “composition”, for which new medical uses are patentable. Therefore, what is the specific distinction between a device and a substance or composition for the purpose of a medical use claims? The EPO’s Board of Appeal noted in T 1758/15 that “every device is ultimately made from chemical substances or compositions”. The case law on this issue has, until fairly recently, focused on the cause of the therapeutic effect of the product (i.e. the mode of action) in determining whether the product is a substance/composition or is a device. However, a Board of Appeal decision in early 2024 (T 1252/20) took a different approach to determining whether the product is a substance/composition. While this change of approach has been hailed as broadening the scope of products which may be considered to be a “substance or composition”, and therefore eligible for a medical use claim, clarity of how this new approach will be applied in practice to all products is still lacking.

Until February 2024, the approach to determining whether a product is a substance/composition for the purpose of a medical use claim was that set out in T 2003/08. The claims of the application in question were directed to the use of a column for the treatment of dilated cardiomyopathy, wherein the column has a specific ligand for human immunoglobulin coupled to it. The EPO’s Board of Appeal decided that the terms “substance” and “composition” in Article 54(4) and (5) EPC refer to products which qualify as chemical entities or compositions of chemical entities. The Board of Appeal also held that, in order for the product to be eligible for a medical use claim, it must be the substance or composition which is responsible for the medical (i.e. therapeutic) effect – in other words, the substance or composition is the active ingredient in the medical use. In particular, the Board of Appeal stated that:

“it is decisive for determining whether or not a "substance" or "composition" is used in a treatment to establish (a) the means by which the therapeutic effect is achieved and (b) whether that which achieves the therapeutic effect is a chemical entity or composition of chemical entities” (Paragraph 18 of T 2003/08).

The Board of Appeal subsequently identified that the therapeutic effect was provided by the ligand, which removed immunoglobulin from the plasma of the patient, and not by the column, which was a device. As the ligand is a chemical entity, the Board of Appeal considered that the product used for the treatment of dilated cardiomyopathy was a “substance” or “composition”, and was therefore eligible to be the subject of a medical use claim.

An example of a later case applying the approach set out in T 2003/08 is T 1758/15. In this decision, the EPO’s Board of Appeal held that a biocompatible, biodegradable, injectable filler material was a device, and not a “substance” or “composition”, and was therefore not eligible to be the subject of a medical use claim. In particular, the claims in question were directed to the use of the biocompatible, biodegradable filler material (such as collagen or hyaluronic acid) in radiation therapy, wherein the filler material is injected into a space between a first tissue of the body and a second tissue. The first tissue is then treated by radiation, and the filler material reduces the exposure of the second tissue to the radiation. Applying the approach suggested in T 2003/08 to determine whether the filler material is a substance/composition or a device, the Board of Appeal held that the technical effect of the invention was to reduce radiation-treatment-induced side effects on sensitive organs, and that this technical effect is achieved “by a mechanical displacement of the sensitive tissue relative to the target tissue, thereby increasing the distance between the two” (paragraph 5.2.8 of T 1758/15). The Board of Appeal considered that this mechanical displacement (and therefore therapeutic effect) was achieved by the 3D structure of the filler material, and not due to the specific substance from which the 3D structure was made, nor to the chemical properties of the filler material. Consequently, the Board of Appeal decided that the filler material was a medical device, and not a “substance” or “composition”, and therefore not eligible for a medical use claim.

T 1252/20, issued in February 2024, took a different approach from that of T 2003/08. In particular, the Board of Appeal considered that there is no legal basis for the two-step approach set out in T 2003/08, and that a definition based on the mode of action does not take into account:

1. that “the material acting inside the body may not be the same than [sic] the material the claim is directed to” (paragraph 10.1 of T 1252/20),
2. that “the mechanism of action may not be understood in detail, or original assumptions about the mechanism of action may later turn out to be wrong” (paragraph 10.2 of T 1252/20), and
3. that “a material may behave in different ways according to its mode of administration” (paragraph 10.3 of T 1252/20).

Instead, the Board of Appeal held that a product is determined to be a substance/composition or a medical device on the basis of the claimed material or object as such.

The claims in question in T 1252/20 were directed to a composition for use in reducing or eliminating cancerous cells in a subject by at least partially blocking the blood supply to the cancerous cells. The composition contained an amphiphilic peptide having a specific amino acid sequence, which formed a hydrogel upon contact with body fluids in order to create the blockage. The Board of Appeal noted that the claims of a patent define the subject matter to be protected, such that it is the subject matter of the claims which must be considered when determining whether the product in question is a substance/composition or a device. In the present case, the claims defined the composition before it was administered to the subject, i.e. as a liquid solution, and in terms of its chemical composition (i.e. the amino acid sequence), and did not recite any technical features which would be characteristic of a device (e.g. its shape; referred to by the Board of Appeal as “device-like features”). The Board of Appeal therefore considered the material defined in the claim to clearly be a “substance or composition”, despite that, once administered, the material transforms into something which may act as a device. 

In other words, it is the definition of the product per se as recited in the claim which must be considered, and not its mode of action and the cause of the therapeutic effect. However, the Board of Appeal noted that the approach set out in T 2003/08 may still be useful in cases where it is not straightforward to determine whether the claimed material reads on to the definition of “substance or composition”.

T 1252/20 has been celebrated as providing a more common sense definition of the term “substance” and “composition”, compared to “device”, and as providing a broader interpretation of the term “substance or composition”. In particular, T 1252/20 reduces the importance of the consideration of the interaction of the product with the body in the interpretation of the terms “substance or composition” for the purpose of Article 54(4) and (5) EPC.  However, on the face of it, it now seems that the determination of whether a product is a substance/composition, and so be eligible for a medical use claim, may depend on the wording of the claim, the responsibility for which rests with the person who drafted the patent application. 

However, there are a number of questions which were not answered in T 1252/20. For example, the Board of Appeal did not elaborate on whether, for a product to be eligible for a medical use claim, there must be no so-called “device-like features” at all included in the claim, how a claim which recites both “device-like features” and chemical composition features should be interpreted, or on the definition of a “device-like feature” (other than shape). It is also unclear as to whether it is the wording of the claim which should be considered when assessing whether the product is a “substance or composition”, or the innate nature of the product claimed.

There does not yet appear to be any further guidance on these issues. In particular, we have not found any Board of Appeal decisions which cite and apply the approach set out in T 1252/20, and there is no mention of T 1252/20 in the current version of the EPO’s Guidelines for Examination. However, we have found one first instance decision by the EPO’s Examining Division (ED) which mentions T 1252/20. In the decision of refusal of European application no. 15869825.8 in March 2025, the ED held that an anlagen organ (for use in treating renal failure an prevention of hydronephrosis and stromal fibrosis, by transplantation) is not a “substance or composition”. In particular, the ED reasoned, with reference to the Travaux Préparatoires relating to Article 52(4) EPC 1973 (corresponding to present Article 54(4) EPC), that the intention of a medical use claim is to “provide the incentive to develop new therapies using already known pharmaceutical compounds or “medicaments”” and that the legal provision for medical use claims “was directed to substances or compositions produced for example by the pharmaceutical industry” (paragraph 4.14 of the decision). The ED went on to state that an organ is not a medicament produced by an industrial process, as it is merely transferred from a donor to a recipient and exerts its normal function in both; and that the organ had no effect per se in the new surgical method to which the application was directed.  Finally, the ED stated that the organ, based simply on its structure, does not qualify as a substance or composition.

Although this decision provides some insight to how the EPO may apply T 1252/20, and the final decision is in line with the EPO’s traditional practice that an organ is not a “substance or composition”, it does not answer all of the outstanding questions, nor provide certainty of a consistent application of T 1252/20. In particular, it is a first instance decision of the specific Examining Division in question, and is not binding on other Examining Divisions. In addition, the claim in question of European application no. 15869825.8 did not contain the same types of features as considered in T 1252/20 – it did not define the organ other than to recite that it is an anlagen of one of three organs. There was therefore no “device-like features” explicitly recited in the claim, for example, shape, as mentioned in T 1252/20. On the other hand, there was also no explicit definition of the chemical composition of the organ, as there was for the product of T 1252/20. Consequently, while the absence of “device-like features” from the claims in T 1252/20 contributed to the decision that the product was a “substance or composition”, the absence of “device-like features” from the claim of European application no. 15869825.8 was not sufficient for the product thereof to be considered a “substance or composition”. Clarity as to the importance of the presence or absence of “device-like features” in the decision of whether a product is a “substance or composition” is likely to be valuable. Similarly, the importance of a definition of the chemical composition of the product, particularly if “device-like features” are also present, remains to be determined.

In summary, the recent shift in the EPO’s approach to the definition of a “substance or composition” under Article 54(4) and (5) EPC, which provide for medical use and second medical use claims, appears, on the face of it, to allow a wider range of products to be considered eligible for a medical use or second medical use claim. However, further clarity on how this new approach should be applied to the wide variety of therapeutic products will be important, particularly given the often complex nature of therapeutics, such as combination therapies, and treatments which combine structure and chemical composition. In the meantime, this author suggests that practitioners should try to ensure that the chemical composition of a product is emphasised, and any “device-like features” avoided, in medical use and second medical use claims.

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