While this decision was one of two decisions handed down on the same day that define the UPC’s general approach to the assessment of inventive step, we will focus here on the guidance specifically applicable to biotech and medical use claims, and how it aligns with or departs from the practice of the European Patent Office (EPO).
The decision relates to patent EP3666797B1 owned by Amgen, Inc. (hereinafter “Amgen”), which was revoked for lack of inventive step on July 16, 2024 by the Central Division in Munich (“CD Munich”) in the context of both a revocation action and a counterclaim for revocation brought by various subsidiaries of the Sanofi group (“Sanofi”) and Regeneron Pharmaceuticals Inc. (“Regeneron”).
At the EPO, the Opposition Division upheld the patent and rejected the oppositions on May 21, 2025.
The patent relates to the medical use of monoclonal anti-PCSK9 antibodies or fragments thereof in the treatment or prevention of hypercholesterolemia or related diseases, wherein the antibodies are defined solely by functional features (binding to the catalytic domain of PCSK9 defined by a specific sequence and preventing or reducing the binding of PCSK9 to LDLR).
At first instance, the CD Munich held that the claims did not contain any feature requiring a specific degree of cholesterol reduction, such that any level of reduction fell within the scope of the claims, which contributed to its finding of lack of inventive step.
By contrast, the CoA held that when claims are drafted in a ‘medical use format’, they should be interpreted as inherently comprising the functional feature that the claimed product must be therapeutically effective, irrespective of their precise wording.
Such an inherent feature requires that the claimed treatment causes a noticeable improvement of the medical condition of the patient suffering from the disease mentioned in the claim, i.e. the treatment must be meaningful.
In the context of patent EP3666797B1, this means that the claims do not encompass any arbitrary reduction in cholesterol levels, but only reductions sufficient to achieve a meaningful therapeutic effect in the treatment of hypercholesterolemia and related diseases.
This approach is consistent with established EPO practice.
The anti-PCSK9 antibodies were defined purely in functional terms, and Sanofi and Regeneron argued that the skilled person would be unable to carry out the invention across the full scope of the claims without undue burden.
While they raised numerous arguments regarding technical difficulties, unpredictability and the breadth of the claims, they did not provide experimental evidence demonstrating that obtaining further antibodies within the claimed definition would indeed involve an undue burden.
Instead, in the context of inventive step, they simultaneously argued that the skilled person could have obtained such antibodies using routine techniques available at the priority date, resulting in internally inconsistent submissions.
In its decision, the CoA essentially applied principles consistent with EPO case law:
Here, the patent described several techniques for identifying antibodies binding to the catalytic domain of PCSK9.
In the absence of evidence of failure provided by Sanofi and Regeneron, and in view of their contradictory positions taken in the context of sufficiency and inventive step, the CoA found that the claims met the requirement of sufficiency.
This ruling suggests that, provided methods for obtaining further antibodies are disclosed, broad functionally defined claims may not only be granted by the EPO but also upheld before the UPC, which will be reassuring for applicants in the biotechnology and pharmaceutical fields.
Notably, this contrasts sharply with the approach taken by the US Supreme Court in similar circumstances, where comparable functional claims were held not to satisfy the written description and enablement requirements.
Finally, in line with its interpretation of medical use claims, the CoA assessed whether there were serious doubts as to the therapeutic effectiveness of the claimed antibodies.
In light of:
the CoA concluded that the requirement of sufficiency was satisfied.
This approach is also consistent with EPO practice, which accepts in vitro and animal model data where such models are directly relevant to the pathology concerned.
This decision is one of two issued on the same day that define the UPC’s approach to inventive step.
The CoA adopts a “holistic approach”, which differs from the EPO’s problem-solution approach, although both approaches may ultimately lead to the same outcome.
In particular, rather than starting from a single closest prior art, the UPC approach begins by identifying the objective technical problem by considering the invention as a whole, including the description and drawings, and the underlying technical teaching (i.e. the technical effect(s) that the skilled person on the basis of the application understands is (are) achieved with the claimed invention).
However, this first step remains somewhat unclear and would benefit from further clarification, especially as the CoA does not appear to apply it explicitly in the present case. It is indeed not very clear to what (the whole state of the art?) the claims should be compared in order to define the objective technical problem.
The assessment of obviousness is then carried out starting from one or more realistic starting points. From each realistic starting point, the invention is obvious if the skilled person, seeking to solve the objective technical problem, would have arrived at the claimed solution.
As before the EPO:
The CoA further emphasises that:
Importantly, the CoA places the burden of proof on the party alleging invalidity. Where the patentee identifies plausible uncertainties or technical obstacles, the burden shifts to the challenger to show that success would nevertheless have been reasonably expected.
In highly unpredictable fields such as biotechnology and pharmaceuticals, this may set a relatively high bar for revocation actions based on obviousness.
The CoA nevertheless recognises that a strong pointer in the prior art may lower the level of expectation of success required.
Decision UPC_CoA_528/2024 provides significant guidance on the interpretation of medical use claims and the assessment of sufficiency and inventive step before the UPC.
While the holistic approach to inventive step assessment differs from the EPO problem-solution approach, it retains key concepts such as the “could-would” test and reasonable expectation of success. Further case law will be necessary to clarify its practical application, in particular the initial step, which is neither clearly explained nor put into practice in the case at hand in the present decision.
By contrast, the approaches to claim interpretation and sufficiency of the UPC appear closely aligned with EPO practice.
Overall, the decision suggests that a relatively high standard of proof is imposed on parties seeking revocation of patents relating to medical uses.
Regimbeau’s biotechnology and pharmaceutical teams will continue to monitor UPC case law developments closely, in order to provide adapted strategic guidance to their clients.
