UPC Aligns Functional Antibody Claims with EPO Sufficiency Standards

A Jones Day commentary explains that, following the US Supreme Court’s 2023 ruling in Amgen Inc. v. Sanofi, which invalidated genus claims for lack of enablement, the drafting focus in the US has shifted toward structurally defined antibodies, such as complementarity-determining regions.

European practice, however, continues to support functionally defined antibodies, including epitope-specific claims. The recent Unified Patent Court (UPC) Court of Appeal decision in UPC_CoA_529/2024 further confirms Europe’s more permissive approach, providing clarity on sufficiency and inventive step standards for broad functional antibody claims.

The case concerns European patent EP3666797, which defines an anti-PCSK9 antibody genus based on its binding region and function to inhibit PCSK9-LDLR interaction. The Munich Central Division initially revoked the patent in July 2024, while the European Patent Office (EPO) maintained it in May 2025.

The UPC Court of Appeal, in its November 25, 2025, decision, overturned the first-instance revocation.

The Court’s ruling aligns sufficiency requirements with established EPO jurisprudence, emphasizing that demonstrating a single method or technical concept for practicing the invention satisfies the standard. Functional features do not require disclosure for every possible embodiment, and routine experimentation by a skilled person is permissible.

On inventive steps, the Court of Appeal endorsed flexibility, rejecting strict adherence to the EPO’s problem-solution approach. Instead, it focuses on evidence-based, case-by-case evaluation, assessing whether the skilled person had a reasonable expectation of success.

This approach maintains consistency with EPO principles on non-obviousness while providing patentees with strategic latitude in structuring functional antibody claims.

For lawyers advising life sciences clients, the decision signals that Europe remains a favorable venue for broad, functionally defined antibody claims. Drafting strategies may leverage functional definitions with confidence that sufficiency and inventive step standards will be interpreted in line with EPO practice.

While US enablement remains stricter, the UPC now provides predictability and alignment for patent enforcement across European jurisdictions.