EPO Clarifies What Is Meant by a “Substance or Composition” Eligible for a Medical Use Claim

At the European Patent Office, methods of medical treatment of the human or animal body are excluded from patentability under Article 53(c) EPC. However, under Articles 54(4) and (5) EPC it is possible to claim a “substance or composition for use” in a method of treatment by surgery or therapy, or a diagnostic method (commonly referred to as purpose-limited product claims).

Importantly, it is only possible to claim a “substance or composition” at the EPO in purpose-limited format, not other products. Most notably, medical devices are not eligible for such protection. It might be tempting to think that it is obvious what constitutes a “substance or composition” in this context, and what is instead a device. However, certain cases have prompted a surprising amount of debate on this issue. In particular, the extent to which the mode of action by which a product exerts its effect on the human or animal body should be considered when assessing whether it qualifies as a “substance or composition” has proved contentious.

Decision T 2003/08 established the principle that in order for a product to qualify as a “substance or composition” within the meaning of Articles 54(4) and (5) EPC, it must be an “active agent” in the method. Furthermore, it was held necessary to establish (a) the means by which the therapeutic effect is achieved, and (b) that the therapeutic effect was achieved by a chemical entity, or a composition of chemical entities.

These principles were further developed in decision T 1758/15. This case concerned a filler material that was injected into a space between two tissues in the body, for use in a method of radiation treatment. The filler material reduced the passage of radiation from a tissue that was targeted for treatment into neighbouring healthy tissues. The board held that because the filler material exerted its therapeutic effect through its physical mass rather than its chemical properties, step (b) of the T 2003/08 test was not satisfied, i.e. the therapeutic effect was not achieved by a “chemical entity”. Rather, the filler material was considered to be acting as a “device”. Thus, purpose-limited protection for the product was denied.

For several years, the EPO has been following the reasoning of T 1758/15 in evaluating what constitutes a “substance or composition”, and incorporated the criteria developed in that case into the Guidelines for Examination. However, the recent decision in T 1252/20 has simplified the test to be applied, and explicitly overturned the reasoning of the board in T 1758/15.

The claim at issue in T 1252/20 concerns a peptide solution for use in a method of reducing or eliminating cancerous cells in a subject by forming a partial blockage in a blood vessel to deprive a tumour of blood supply. The examining division had held that the peptide exerts its therapeutic activity through forming a polymeric hydrogel structure in vivo which physically prevents blood from reaching the tumour, and refused the application following the principles set out in the Guidelines and T 1758/15. However, the board of appeal disagreed, and considered that purpose-limited protection should be available.

In particular, the board considered there was no doubt that a solution of a peptide should be considered a “substance or composition” under the normal meaning of that language. Moreover, the claim itself was directed to a solution form of the peptide (any solid mass only being formed in vivo) and lacked any features reminiscent of a “device”, e.g. its shape. The board did not see any reason to deny purpose-limited product protection simply because after administration to a patient, the solution might transform into something which may act as if it were a device.

The board went on to hold that it could find no legal basis under the EPC for considering the mode of action as a criterion for qualifying a material or object as a substance or composition under Articles 54(4) and (5) EPC. Moreover, the board noted several practical difficulties with applying a mode of action criterion, including (i) the material acting inside the body may not be the same as the material defined in the claim, e.g. in the common case of a prodrug, (ii) that it is not a requirement of the EPC that the mechanism of action of a medicament be understood in detail, and (iii) the method of administration may affect the mechanism of action of a medicament.

Accordingly, the board concluded that where it is “immediately apparent from the claimed material as such” that the claimed product has a substance-or-composition-like nature, no additional criteria need be applied. The criteria (a) and (b) developed in T 2003/08 could potentially be helpful in cases where it is not otherwise straightforward to reach that conclusion, but are not mandatory under the EPC.

This decision therefore represents a welcome liberalisation of the EPO caselaw on medical use claims. As noted by the board itself, the legislative intent of Articles 54(4) and (5) EPC was to provide a route to patentability for inventions that are worthy of protection, but which would otherwise fall under the exclusion of Article 53(c) EPC. Interpreting the term “substance or composition” in an unduly narrow way merely frustrates this intention. Whilst there will inevitably be some borderline cases, T 1252/20 is a well-reasoned decision that provides a clear and simplified test for determining eligibility of products for purpose-limited protection.