EPO Board of Appeal Extend Definition of "Substance or Composition" in Medical Use Claims

The recent decision of the EPO Board of Appeal in case T-1252/20 marks a significant shift, broadening the category of products eligible for medical second-use claims. This decision has considerable implications for the patentability of medical treatment-related products at the European Patent Office (EPO). While methods of treatment are not patentable at the EPO, Article 53(c) of the European Patent Convention (EPC) allows for the patentability of "substances or compositions for use" in methods of treatment, surgery or diagnosis.

To provide some context, the EPC defines a "substance or composition" as an "active ingredient" that provides a therapeutic effect in a medicinal product. However, past case law established that only those products that interact chemically with the body are considered "substances or compositions", while those whose therapeutic effect is based on a "three-dimensional structure formed by a composition once inside the body" (in other words, whose action is purely mechanical rather than chemical) are classified as devices. The distinction between a "substance or composition" and a medical device has been the subject of recent legal controversy. This is for a simple reason: while second-use claims are allowed for substances and compositions as per Articles 54(4) and (5) of the EPC, they are not allowed for devices.

The decision in case T-1252/20 represents a change in this interpretation by including any product defined by its chemical composition in the category of 'substance or composition', regardless of its mode of action in the body.

In this case, the Board of Appeal reviewed the decision of the Examination Division to reject patent EP 2919826, which covered a composition for reducing or eliminating cancer cells by blocking the blood supply to the tumour. The Examination Division argued that the peptide used in the composition had a physical mode of action by forming a hydrogel and therefore did not qualify as a "substance or composition" under Article 54(4) and (5) EPC. However, the Board of Appeal held, contrary to existing case law, that the peptide hydrogel should be classified as a "substance or composition" on the basis of its basic chemical properties.

The Board of Appeal held that even if the mode of action is physical, the product should still be considered a 'substance or composition' if its chemical composition is fundamental to its therapeutic effectiveness. As an example, consider a topical gel used to relieve muscle pain. Although its mode of action is physical in that it forms a layer on the skin that provides relief, the Appeals Board would argue that it should be classified as a 'substance or composition' if its chemical composition, such as the active analgesic ingredient, is essential to its therapeutic effectiveness.

In this context, the Appeals Board concluded that restricting the definition of "substance or composition" by mode of action would not adequately fulfil the legislative purpose of Article 54(4) and (5) EPC. In this case, the Board argued that the product should be considered a "substance or composition" for patentability purposes, as its chemical composition and physical properties are equally relevant to its therapeutic efficacy. Overall, the Board's approach would allow for a more flexible interpretation of patentability requirements for compositions with medical use.