Divergence Resolved – UPC And EPO Now Aligned On Medical Uses / Antibodies

Last year, we reported on a divergence in first instance decisions between the EPO and the UPC when assessing the inventive step of a medical use. The UPC first instance proceedings concluded that Amgen’s EP3666797 lacked an inventive step, but the EPO opposition division found the same patent inventive. Following the conclusion of appeals at both tribunals, this divergence has now been resolved by the UPC aligning with the EPO. Amgen’s patent is therefore upheld as inventive.

The November 2025 decision of the UPC Court of Appeal (CoA) began the alignment by reversing the first instance decision of the Central division and – as we reported at the time – it also established some key principles for inventive step and medical use inventions. This alignment was then confirmed in March 2026, when the EPO’s first instance decision became final upon closure of the appeal proceedings by withdrawal of the opponents’ appeals. This appears to have been prompted by a settlement between the parties. Some of the most important points of alignment between the UPC and EPO are discussed below.

Background

These cases formed part of the long-standing, but now evidently settled, global dispute between Amgen and Sanofi/Regeneron in the anti-PCSK9 antibody space. Sanofi and Regeneron market the drug Praluent^®, while Amgen market the drug Repatha^®.

PCSK9 triggers the degradation of low-density lipoprotein receptors (LDLRs) on liver cells, which means these cells have reduced capacity to remove LDL cholesterol from the blood. By binding to PCSK9 and blocking the interaction with LDLR, anti-PCSK9 antibodies assist in lowering blood LDL concentrations, thereby reducing the amount of cholesterol circulating in the bloodstream.

Amgen’s patent EP 3666797 (‘797) is part of a large family comprising 13 divisional applications. The original parent patent granted with a main claim directed to an antibody binding to human PCSK9 that competes with specific reference antibodies and having neutralising activity. This product claim was invalidated for lack of inventive step by the EPO during appeal proceedings and the patent was ultimately maintained with sequence-based claims directed to specific antibodies.

In the ‘797 patent, claim 1 refers to a monoclonal antibody or an antigen-binding fragment thereof for use in:

• treating or preventing hypercholesterolemia or an atherosclerotic disease related to elevated serum cholesterol levels; or
• reducing the risk of a recurrent cardiovascular event related to elevated serum cholesterol levels.

The antibody or antigen-binding fragment in claim 1 is also functionally defined as binding to the catalytic domain of a PCSK9 protein of the amino acid sequence of SEQ ID NO: 1, and preventing or reducing the binding of PCSK9 to LDLR.

Assessment of inventive step – reasonable expectation of success

As we reported, in its decision bringing it into alignment with the EPO, the UPC CoA first reiterated the framework for assessment of inventive step as first established in UPC_CoA_335/2023 (NanoString/10x Genomics). This has been described as a more “holistic” approach than the EPO’s strict “problem-solution” approach, but it shares the same basic principles.

The key to the decision in this case was whether the skilled person would have had a reasonable expectation of success when moving from the prior art to the claimed invention. The CoA ultimately concluded that uncertainty about the mechanism by which PCSK9 lowers cholesterol meant that, at the priority date, there would not have been a reasonable expectation that anti-PCSK9 antibodies would be effective to treat conditions such as hypercholesterolemia and atherosclerotic disease. This follows similar reasoning applied by the EPO opposition division.

Interpretation of medical use claims

The CoA dismissed an argument for lack of inventive step which alleged that the skilled person would have expected at least some degree of cholesterol-lowering effects from anti-PCSK9 antibodies. This argument relied on interpreting the medical uses defined in the claims as encompassing such lowering of cholesterol levels.

Finding against the argument, the CoA confirmed that medical use claims must be interpreted as requiring a “meaningful” treatment effect for the diseases that are mentioned in the claims. Such claims require a noticeable improvement in the medical condition of the patient suffering from those diseases. It is this “meaningful” treatment effect that could not reasonably be expected from the prior art. This mirrors the central importance in the EPO opposition division decision of (the lack of) a reasonable expectation of a “therapeutic effect” in the conditions recited in the claims.

Sufficiency – broad antibody definitions are patentable

The CoA stated:

“Where a claim contains one or more functional features, it is not required that the disclosure includes specific instructions as to how each and every conceivable embodiment within the functional definition(s) should be obtained. A fair protection requires that variants of specifically disclosed embodiments that are equally suitable to achieve the same effect, which could not have been envisaged without the invention, should also be protected by the claim. Consequently, any non-availability of some embodiments of a functionally defined claim is immaterial to sufficiency, as long as the skilled person through the disclosure is able to obtain suitable embodiments within the scope of the claim.”

This effectively endorses the EPO’s long-standing practice of allowing relatively broad definitions of antibodies in claims, particularly where the invention primarily concerns the identification of the target and/or its role in disease. This contrasts significantly with the strict assessment of enablement in the US courts, which now typically require narrow, structural definitions for most antibody claims.

Final points

With the closure of the EPO appeal, the alignment of the UPC and the EPO on the issues covered by these parallel proceedings is now confirmed.

Agreement between the two tribunals on inventive step is particularly welcome, given that their approaches are not identical. The UPC’s “holistic approach” has some subtle differences relative to the EPO’s “problem-solution”, although both approaches follow the same basic principles. It is encouraging that the UPC CoA has emphasised that, when properly applied, the two approaches should generally lead to the same conclusion.

Similarly, confirmation of the alignment between the UPC and the EPO on the sufficiency of broadly-defined antibodies and the interpretation of medical use claims is a positive step. Continuing consistency between these two major European tribunals will increase certainty for patent holders and other interested parties.

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