Antibodies have recently been receiving a lot of close attention at the European Patent Office (EPO), not least with a new section in the latest EPO Guidelines for Examination devoted to the complex case law relating to the field of antibody inventions. One of the issues covered by these new guidelines for EPO examiners is the situation where an antibody is defined by reference to a deposited hybridoma. This is specifically permitted by Rule 31 European Patent Convention (EPC), which deals with sufficiency of disclosure. However, recent Board of Appeal decision T 0032/17 found that mere reference to a hybridoma does not limit an antibody claim to a particular structure or sequence, making it harder for those applicants attempting to rely on deposit information to define their antibodies.

European Patent No. 2316854 was granted with claims directed to a process for production of a hybridoma, and of a monoclonal antibody or fragments thereof, able to recognise specifically recited vitamin D metabolites. Thus, these claims defined the antibody in terms of its functional features and the process used to produce it, rather than in terms of the structural characteristics of the antibody itself.

Further claims in the granted patent were directed to hybridoma suitable for the production of a monoclonal antibody of fragments thereof able to recognise the same vitamin D metabolites.

The patent was opposed by five opponents and following maintenance of the patent in amended form following opposition proceedings, the case was referred to the Board of Appeal.

Technical features conferred by hybridoma deposit information

In their decision T 0032/17, the Technical Board of Appeal of the EPO considered whether:

  1. the process used to produce the antibody gives rise to the specific amino acid sequence and chemical composition of the claimed antibodies; and
  2. the skilled person is made aware of these structural characteristics of the antibodies by the teaching of the patent.

The patent did not provide any information about the chemical composition or amino acid sequence of the antibodies produced by the deposited hybridomas. As a result, the Board of Appeal found that “it is apparent that the chemical composition and/or the amino acid sequence of the antibodies produced by the deposited hybridomas cannot be inferred by the skilled person from the teaching of the patent in suit”. The Board of Appeal concluded that the process feature does not impart any identifiable technical feature on the claimed subject-matter and the sole technical feature defining the claimed monoclonal antibodies was the functional feature.

The Board of Appeal went on to state that, where a process feature is the only feature allegedly conferring novelty to a product, the burden of proof for showing that the process feature results in a distinct and identifiable characteristic of the product (in the present case, this is the chemical composition and/or the specific amino acid sequences of the antibodies) falls on the patentee rather than on the opponent. In view of this, the patentee’s mere argument that the skilled person could have determined the amino acid sequence of the antibodies produced using the deposited hybridomas was not deemed enough to discharge the burden of proof.

Availability to the public of the deposited hybridoma

The Board of Appeal also considered whether the claimed hybridomas were novel in light of the fact that they were deposited before the application was filed. In addition, the hybridomas were also mentioned in a product catalogue pre-dating the patent application. The parties attacking the validity of the patent alleged that the deposit of the hybridomas rendered them available to the public before the priority date. They also argued that the mention of the hybridomas in the catalogue constituted prior use of the claimed antibodies.

The Board of Appeal noted that Rule 33(1) EPC provides that biological material (e.g. a hybridoma) “shall be available upon request to any person from the date of publication”.  As such, deposited hybridomas are made available to the public when the patent application is published. The Board of Appeal noted that there was a lack of evidence that anyone had obtained a sample before the application in question had been published and so the Board of Appeal found that the public availability of the deposited hybridomas post-dated the filing date of the application and that the depositing of the hybridomas before the priority date was not novelty destroying to the hybridoma product claim.

This decision on the availability to the public appears to suggest a divergence in the approach of the EPO and the  courts of the United Kingdom on the question of disclosure. Recent case Claydon v Mzuri[1] held that the test of prior use in the UK is the “potentialityfor public disclosure, rather than being a question of whether it had actually been disclosed. It remains to be seen how these two different approaches to this pivotal question develop before the EPO and the UK courts in future.


[1] [2021] EWHC 1007 (IPEC)