Board of Appeal case T 0424/21 and the Allowance of Broad Antibody Patent Claims by the European Patent Office

In the recently issued Decision of the European Patent Office Boards of Appeal, T 0424/21, further evidence is provided that broad antibody patent claims can be obtained in Europe, with the claim scope being much broader than that allowed by the USPTO.

Antibodies are composed of two different types of domain, i.e. the type that binds to target antigens with a high specificity, and the structurally constant domains, known as Fc regions. A potential limitation on the use of therapeutic antibodies is that binding of the Fc regions of the antibodies to specific receptors in the body, such as Fc receptors (FcRs), can induce unwanted side-effects, such as by activating cells of the immune system. The patent at issue in T 0424/21 related to a modified antibody Fc region that has a reduced ability to bind to FcRs and thereby reduced ability to activate detrimental immune responses.

The independent claims upheld on appeal defined antibodies only on the basis that “the Fc region contains amino acid substitutions P329G, L234A and L235A”. Thus, the claims include no limitation whatsoever on the antibody binding specificity, and potentially encompass antibodies specific for any target antigen. The dependent claims introduce only functional limitations, including reduced antibody dependent cell killing (claim 2), reduced binding to FcRs (claim 3), and use as a medicament (claim 6).

The Opponent alleged that the claims lack sufficiency of disclosure over the entire scope of the claims. However, the Boards of Appeal dismissed the Opponent’s insufficiency allegation on the basis that Fc regions “are commonly known”, and because the Opponent did not assert any serious doubts that the skilled person would be able to obtain the claimed antibodies.

In relation to the functional features of the dependent claims, although only two antibodies were demonstrated in the patent specification, the Board found that the Opponent had not provided any evidence that the effects were restricted to the particular antibodies used in the examples, and that “the Board sees no reason to assume this to be the case”. On this basis, therefore, the Board found that the patent enables the skilled person to obtain antibodies or Fc fusion proteins having the recited functional features of the claims without undue burden.

The scope of the claims upheld by the Boards of Appeal provide a remarkable illustration of the stark contrast between the broad scope for antibody patents that is still obtainable in Europe versus the high bar for written description and enablement requirements in the U.S.

If you would like more information about patenting antibodies, please contact our specialist Antibody Team, who would be happy to assist. We have considerable experience in drafting and prosecuting antibody patent applications, and also in proceedings before the European Patent Office Opposition Divisions and Boards of Appeal challenging and defending antibody patents.

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