First medical use claims in European patent applications

Must a compound be shown to be suitable for each disease for first medical use claims to be sufficiently disclosed in applications for European patents, asks Matthieu Boulard. 

Article 54(4) of the European Patent Convention (EPC), dealing with first medical use claims, provides that it is possible to claim a known substance or composition for use as a medicine, even if said application is not known. However, Article 83 of the EPC states that an invention must be disclosed in the patent application in a manner sufficiently clear and complete for a person skilled in the art to carry it out. The simultaneous observance of these two articles is at the heart of a case  (T 424/21) that was considered recently by the Board of Appeal of the European Patent Office (EPO).

When is an invention too broad to be registered?

The medical invention in this case relates to proteins, in particular antibodies, comprising one or more mutations inducing therapeutically relevant effects. Proteins are complex molecules of amino acids, constituting the essential part of organic matter and living beings.

During the opposition procedure, two points of view were presented.

On the one hand, the opponent argued that the invention did not work for a large number of medical uses and that, in the absence of a selected list of diseases in the patent, it was necessary to carry out too many experiments to establish whether the proteins covered by the patent had effects on arbitrarily selected diseases. 

Thus, the opponent explained that this amounted to setting up a research program to provide a safe and effective treatment regime, which was an unreasonable burden on the skilled person. The conclusion of his argument was that in the absence of an exhaustive list of diseases, not all the relevant molecules were known, and that a first medical use claim in the present case could not be sufficiently clear and complete within the meaning of Article 83 EPC. 

On the other hand, the patentee argued that there was no reason why a first medical use claim should not be allowed since in the same patent a broader claim covering the said proteins without specifying their use had been accepted. 

The patentee also pointed out that, on the basis of the data provided in the patent for a limited number of proteins according to the invention and the general knowledge of the person skilled in the art, the latter would have no difficulty in identifying a protein suitable for a given medical use and introducing a mutation according to the invention for use in a disease in which the protein was effective.

The Board of Appeal’s decision

In reaching its decision in T 424/21, the Board of Appeal looked to case law on the issue of sufficiency of disclosure of a first medical use claim. However, the list of decisions on similar issues is far from extensive and generally concerns situations where, unlike in the present case, the substance or composition is already known (in accordance with Article 54(4) EPC 2000). 

However, for the question of whether the ‘medical use’ aspect of the claim is sufficiently disclosed, the Board of Appeal considered that the distinction regarding the novelty of the substance or composition is not relevant. 

In particular, it cited decision G 5/83, reasons 15, in which the Enlarged Board of Appeal stated that an inventor can obtain a first medical use claim for a known substance without having to limit the substance to a technically suitable form (pill, powder, syrup etc) for a specific medical use. Thus, for the Enlarged Board of Appeal, the appropriate protection was a product claim limited to a broad medical use. 

In the present decision, the Board of Appeal interprets this statement to mean that the Enlarged Board of Appeal, although not explicitly commenting on Article 83 EPC, did not see a general problem of sufficiency of description for a broad first medical use claim and did not see the need for the inventor to limit themselves to a specific medical use.

Furthermore, prior to the G 5/83 decision, the T 128/82 decision had taken the same direction regarding the general practice of the EPO by stating that: " If an inventor is granted absolute protection in respect of a new chemical compound for use in therapy, the principle of equal treatment would require that an inventor who for the first time makes a known compound available for therapy should be correspondingly rewarded for his service with a purpose-limited substance claim under Article 54(5) EPC to cover the whole field of therapy". 

In addition, T 128/82 stated that: " The mere fact that there are not instructions concerning all and any possible specific therapeutic applications does not justify limiting the scope to the therapeutic application actually mentioned. This would not be in accord with the general practice of the European Patent Office concerning therapeutically active compounds.” 

Following the analysis of all the points raised in the present case, the Board of Appeal indicated that it cannot derive any requirement from the EPC that a patent application should demonstrate that a compound is suitable for each disease in order for a first medical use claim to be sufficiently disclosed. 

Thus, with respect to the sufficiency of description requirement for a first medical use claim, it is sufficient to demonstrate that a substance or composition is suitable for at least one particular medical use and not an exhaustive list. 

If you have any questions about this ruling or any other case law developments, do not hesitate to consult our patent attorneys. Our specialist team is on hand to assist you with all your invention protection procedures in the pharmaceutical field.

Matthieu Boulard is a Patent Attorney at Novagraaf in France.