Inventive Step – Patenting Antibody Related Inventions at the EPO

This article illustrates the Inventive Step as a follow up to Patenting Antibody Related Inventions at the EPO

Inventive Step

The subject-matter of a claim defining a novel, further antibody to a known antigen does not involve inventive step unless a surprising technical effect is shown.

The EPO’s viewpoint is that the generation of an antibody to a known antigen merely involves routine experimentation. It would be common practice for a party to create alternative antibodies using known techniques.

The EPO does not recognize structural non-obviousness, whereas the USPTO does. The EPO requires additional proof to establish inventive step, namely that there is a surprising technical effect.


  • 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 vs 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.

If the surprising technical effect involves the binding affinity, the structural requirements for conventional antibodies must comprise the 6 CDRs and the framework regions as these regions can influence the affinity.

Antibodies are considered inventive if technical difficulties are overcome in producing / manufacturing the antibodies. For the EPO to acknowledge inventive step, experimental data evidence is required to demonstrate the surprising technical effect relied on.

The data in the application should state that the antibody binds to the intended target and has its intended biological effect as expected and that the antibody has a functional characteristic beyond similar antibodies.

The EPO will typically require the following forms of information or supporting data:

  • Structural information for at least one exemplary antibody
  • The antibody binds to the target and has some functional effect(s)
  • The antibody has an unexpected effect / functional characteristic that can be relied on.

Post-filing evidence can be taken into account to show an advantage. That is if it was plausible based on the information in the application. Post-filed data that can be used to:

  • confirm that an effect that was made plausible in the application is actually seen (for example, in vivo therapy).
  • directly compare the antibody with a prior art antibody and show the effect proposed in the application is seen.

The EPO has now adopted a stricter approach.

It is worth considering the scope and category of the claims and what to include:

  • Data demonstrating target specificity and affinity, describing the target binding measuring techniques in general terms.
  • At least one specific example of the preferred test method (e.g., surface plasmon resonance), including the specific experimental conditions used for measuring target binding affinity of the exemplary antibodies of the application as well as the required binding values for adequate and preferred affinity binding produced by that method
  • Demonstration of an unexpected technical effect or an improved property is usually required to establish an inventive step (Boards of Appeal decisions T 735/00  and T 605/14). Suitable examples include an improved affinity, specificity, immunogenicity, neutralising properties, inhibition or activation of receptors, bioavailability, solubility

  • The technical effect/ improved property is shared by all antibodies falling within the claim scope to meet the inventive step.
  • The technical effect relied upon must be at least plausible at the filing date in view of the disclosure in the application (Boards of Appeal decision T 1329/04)
  • Later filed supporting data must be related to the same technical effect as the one disclosed in the originally filed application. Evidence even of a related functional characteristic may not be considered as adequate support to meet the requirement (Boards of Appeal decision T 2637/11)
  • A description of multiple properties of the antibodies, such as specificity, cross reactivity and neutralizing potency. It can be difficult to rely on post-filing data to support inventive steps. Unless the new data is ‘plausible’ based on the application as filed
  • Risks of filing a patent application in the early stages of research with only structural information. File the patent with initial supporting data. Written with a view to providing further experimental work if needed later in prosecution
  • The preceding requirements also apply to other classes of claims, for example to compositions comprising the antibodies or the antibodies for use in treating a disease