In March 2021, the European Patent Office (EPO) Guidelines for Examination were updated to include, for the first time, a section devoted to the examination of antibody-related patent applications (Guidelines G-II, 5.6), as discussed in our previous article here.
In the 2024 update to the Guidelines, which enters into force on 1 March 2024, a few interesting amendments to the Antibodies section have been made.
The Guidelines list a number of specific approaches by which antibodies may be defined in patent claims and discuss the specific requirements for each of these various approaches to claiming antibodies. These approaches include, for example, antibody definitions based on structure, function, target, and/or method of production.
In the 2024 Guidelines the section relating to defining antibodies on the basis of the epitope has been combined with the section relating to defining antibodies using a combination of the target antigen and a further functional feature. As a result of this amendment, specific requirements relating to the definition of linear and discontinuous epitopes have been removed entirely from the Guidelines, potentially providing more flexibility for Applicants.
The amendments to the Guidelines explicitly place the burden of proof on the Applicant for demonstrating the novelty of antibodies defined on the basis of their epitope and/or other functional features. The burden thus lies with the Applicant to show that prior art antibodies do not bind to the same epitope. Similarly, the Applicant must show that a prior art antibody binding to the same target antigen as the claimed antibody does not demonstrate the claimed functional features.
The amended Guidelines also indicate that it may be challenging to successfully claim an antibody on the basis of its ability to compete with a reference antibody, as the EPO has indicated that it may be difficult to search the prior art for antibodies having this property. This is clearly dependent on the specific circumstances, however, and something that Applicants should take into consideration when drafting antibody patent claims.
The amendment of the epitope section of the Guidelines, in particular, is likely due to a recent EPO Board of Appeal decision T 0435/20, in which the patent in suit claimed a genus of antibodies that bind to a specific discontinuous epitope. In this decision, the Board found that the patent was insufficiently disclosed on the basis that a skilled person would not know the nature of the antigen required to raise new antibodies specific for the discontinuous epitope, and that the patent did not disclose a suitable assay to test antibodies. The case is notable because it is an exception to the EPO's general approach that generating new antibodies against a known target is a matter of routine for the skilled person, but clearly in the case of discontinuous epitopes it is important that enough information is included in the specification for the skilled person to be able to reproduce the claimed antibodies.
The section relating to "Inventive step of antibodies" in the 2024 Guidelines has also been amended and arguably provides more freedom to Applicants for arguing that an antibody is inventive. Rather than simply listing examples of the types of technical effect that may support an inventive step, the amended Guidelines refer generally to an "unexpected improvement" and/or "unexpected property" relative to prior art antibodies.
Applicants will also be pleased to note that the 2024 amendments to the Guidelines remove a previous requirement that if the technical effect relied upon for inventive step included an improved binding affinity, then the antibody framework regions must be included in the definition of the claimed antibody, on the basis that the framework regions can also influence the binding affinity.
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