UPC COA Establishes Key Principles For Inventive Step And Medical Use Inventions

In a significant decision issued 25 November 2025, the UPC COA has held Amgen's anti-PCSK9 antibody medical use patent to be inventive, overturning the first instance revocation decision of the Munich Central Division (previously reported here). In doing so, the COA has also aligned with the EPO OD's finding of inventive step of the same patent in a parallel EPO opposition, as reported earlier this year.

In their decision, the COA provides extensive headnotes setting out substantive principles relating to claim interpretation, inventive step and sufficiency which provide important guidance for future cases. The UPC COA also set out in detail their approach to assessment of inventive step of medical use inventions.

Background

Amgen's patent EP3666797 relates to the medical use of an antibody binding to a particular domain of PCSK9 which prevents or reduces binding of PCSK9 to LDLR, for treating or preventing certain conditions related to elevated cholesterol levels.

Further to revocation actions/counterclaims for revocation filed by Sanofi and Regeneron, the Munich Central Division revoked the patent for lack of inventive step on the basis that it would have been obvious to pursue antibodies blocking the PCSK9/LDLR interaction from the conclusions of prior art document Lagace.

In a later decision in the parallel EPO opposition (currently on appeal), the EPO OD concluded otherwise, on the basis that there would not have been a reasonable expectation of success in arriving at the claimed treatment starting from Lagace.

The COA's decision has been keenly awaited as one of the first appeal decisions in full proceedings on the merits at the UPC, involving assessment of various substantive issues including inventive step.

General principles of inventive step

The COA's decision provides the first detailed guidance at appeal level on the approach to inventive step at the UPC. As reviewed in our previous briefing, The UPC's evolving approach to inventive step, the UPC's lower courts had previously developed an approach to assessment of inventive step having various similarities with that of the EPO, but with some divergence between different lower courts as to whether the problem-solution approach should be strictly followed.

In a detailed series of headnotes, the COA's decision sets out the approach to be taken by the UPC on inventive step, endorsing various aspects of the approach taken by the lower courts. In particular, an objective problem should be established, which does not contain pointers to the solution. Obviousness is assessed from a realistic starting point (of which there may be more than one). A realistic starting point may be a prior art with several features similar to the invention and/or addressing the same underlying problem. Obviousness is present if the skilled person would (not only could) have arrived at the claimed solution. The skilled person requires a pointer or motivation directing them to implement a next step in the direction of the claimed invention.

Interestingly, the COA's approach to how the objective problem is determined is holistic, involving "establishing what the invention adds to the state of the art, not by looking at the individual features, but by comparing the claim as a whole.... considering the inventive concept underlying the invention... based on the technical effect(s) achieved with the claimed invention". The COA's approach thus differs from the EPO's problem-solution approach in that the problem is not specifically formulated based on a difference over the prior art, and indeed a realistic starting point is identified after the objective problem has determined. The COA comment later in their decision that different approaches used to assessing inventive step by national courts and the EPO are "just guidelines". However, they also consider that the different approaches should and generally do lead to the same conclusion.

Accordingly, the COA's summary of principles enshrines that the UPC will adopt its own approach to assessment of inventive step, which differs in some respects from that of the EPO.

Reasonable expectation of success of the medical use

Before considering inventive step of the claimed medical use, the COA first commented on how a claim in the medical use format "Agent... for use in treating or preventing..." should be interpreted. They held that such a claim requires "a noticeable improvement of the medical condition of the patient". In doing so, they disagreed with a lower threshold adopted at first instance to the effect that any lowering of cholesterol in vivo would meet the requirements of the claim.

The COA's claim interpretation is generally in line with EPO practice, whereby attainment of a claimed therapeutic effect is read as a functional technical feature of a medical use claim.

The COA then considered whether the claimed (effective) treatment would have been obvious from prior art document Lagace as a starting point.

The COA agreed with the first instance court that Lagace provided strong motivation to develop a treatment blocking PCSK9 activity to reduce levels. However, the COA disagreed that the suggestion of an antibody treatment in Lagace rendered the claimed medical use obvious. Decisive to this was the COA's assessment of the criterion of reasonable expectation of success in arriving at the claimed treatment. In particular, the COA held that there were uncertainties in the prior art as to whether an antibody treatment would be effective, based on both intracellular and extracellular pathways being described for PCSK9, and putative effects not being shown under physiologically relevant conditions.

Accordingly, the COA concluded that the skilled person would not have had a reasonable expectation of success that the route of developing an antibody would lead to a therapeutically effective treatment. They further distinguished this analysis of obviousness from a consideration of whether the skilled person could have developed antibodies within the scope of the claim with a hope to succeed.

The COA's emphasis on a criterion of reasonable expectation of success is in line with EPO practice on assessment of medical use inventions (and other inventions in the area of biology), and also with the OD's findings in the parallel EPO opposition. The COA's decision clarifies that this criterion will also be important to inventive step assessment at the UPC. The decision also sets out various general principles in relation to reasonable expectation of success which provide useful guidelines. In particular, reasonable expectation of success:

• depends on the nature of the technical field;
• implies rational prediction of a successful conclusion within acceptable time limits
• has a lower threshold where there is a stronger pointer in the prior art;
• is the challenger's burden to prove, if the proprietor invokes and sufficiently substantiates uncertainties/difficulties; and
• is not implied merely from the fact other teams were working contemporaneously on the same project, which may instead indicate an area of interest or a hope to succeed.

Findings on other grounds

Although the key issue in the case was inventive step, the COA's decision also provides useful guidance in relation to assessment of sufficiency of disclosure and added matter at the UPC.

In relation to sufficiency, the challengers had invoked the breadth of the claims, which encompassed any antibody having the claimed properties. The COA rejected these arguments on the basis that the identification of other antibodies would not involve an undue burden and also based on a lack of proof of non-enablement of certain embodiments. The COA's findings regarding enablement of a class of antibodies follow the well-established position at the EPO that development of antibodies to a known target is considered routine absent evidence to the contrary. The position on enablement of antibody-related claims in Europe (now both at the UPC and the EPO) thus differs from that in the US, where a claim to a functionally defined class of antibodies was held invalid by the Supreme Court in Sanofi/Amgen for over-breadth.

Turning to added matter, the COA considered an argument common under EPO practice that the claimed subject matter represented an undisclosed combination of features from the original disclosure. They rejected this attack on the basis that the relevant features were preferred (not arbitrary selections) and also linked to each other in some passages of the description. The COA's analysis on added matter generally follows principles applied at the EPO when considering whether added matter has been created through a combination of features.

Alignment with EPO

Finally, the COA's decision is also interesting for the alignment of the COA with the OD on inventive step (reversing the divergent outcome at first instance at the UPC).

In this regard, following the EPO OD's decision issued during the course of the UPC appeal proceedings, the COA rescheduled their appeal hearing to a later date and provided an opportunity for the parties to provide written submissions in relation to the OD's decision. The COA thus gave careful consideration to the OD's decision before arriving at its own conclusions.

The TBA's decision in the parallel EPO appeal is now awaited with interest, with appeal oral proceedings scheduled in April 2026.

Conclusions

The COA's decision provides a first summary of inventive step principles at the UPC at the appeal level, and is thus a major addition to UPC case law. The decision also provides important guidance for assessment of inventive step for inventions in the area of biology, in particular medical use inventions. The findings in the case and attention paid by the COA to the EPO OD's decision also illustrate alignment of the UPC and EPO on assessment of inventive step, albeit using different tests.

J A Kemp LLP acts for clients in the USA, Europe and globally, advising on UK and European patent practice and representing them before the European Patent Office, UKIPO and Unified Patent Court. We have in-depth expertise in a wide range of technologies, including Biotech and Life Sciences, Pharmaceuticals, Software and IT, Chemistry, Electronics and Engineering and many others. See our website to find out more.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.