5.6.1.1 Definition by structure of the antibody 

In order to fulfil the requirements of Art. 84, the structural definition of an antibody must contain at least the sequence of each of the CDRs required for binding to the antigen, which, in the case of an IgG, is CDRs 1-3 of each of the variable domains.

Hence, if an IgG is defined by fewer than its six CDRs, the claim will be objected to under Art. 84 because it lacks essential technical features unless it is experimentally shown that one or more of the six CDRs do not interact with the antigen.

If CDRs are not defined by their specific sequence, but by reference to a larger heavy or light chain sequence, the numbering scheme, for example Kabat, Chothia or IMGT, must also be indicated.

Since the three CDRs of each of the variable domains of the light and heavy chains of an IgG are normally responsible for binding to the antigen, the IgG, in order to be uniquely defined by its structure only and have its characteristic binding specificity, needs to be defined by the number of CDRs required for its binding to fulfil the requirements of Art. 84.

CDRs when not defined by their specific sequence must be defined according to a numbering scheme, for example, chosen from that of Kabat, Chothia or IMGT.

If an IgG is defined by fewer than the six sequences of its CDRs, the claim will be objected to under Art. 84 because it lacks an essential technical feature unless it is experimentally shown that one or more of the six CDRs do not interact with the target epitope or if it concerns a specific antibody format allowing for epitope recognition by fewer CDRs.