The subject-matter of a claim defining a novel, further antibody binding to a known antigen does not involve an inventive step unless a surprising technical effect is shown by the application. Examples of surprising technical effects when compared to known and enabled antibodies are, for example, an improved affinity, an improved therapeutic activity, a reduced toxicity or immunogenicity, an unexpected species cross-reactivity or a new type of antibody format with proven binding activity.
If inventive step relies on an improved property versus the enabled antibodies of the prior art, the main characteristics of the method for determining the property must also be indicated in the claim or indicated by reference to the description (F-IV, 4.11.1).
If the surprising technical effect involves the binding affinity, the structural requirements for conventional antibodies inherently reflecting this affinity must comprise the six CDRs and the framework regions because the framework regions also can influence the affinity.
If a novel antibody binds to the same antigen as known antibodies, inventive step is not acknowledged solely on the basis that the novel antibody is structurally different from the known antibodies. Arriving at alternative antibodies by applying techniques know in the art is considered to be obvious to the skilled person. The fact that the structure of the thus obtained alternative antibodies, i.e. their amino acid sequences, is not predictable is not a reason for considering these antibodies as non-obvious (see T 605/14, section 24; T 187/04, section 11).
Nevertheless, antibodies can be inventive if the application overcomes technical difficulties in producing or manufacturing the claimed antibodies.
Source: http://www.epo.org/law-practice/legal-texts/html/guidelines/e/g_ii_5_6_2.htm
Date retrieved: 17 May 2021