UPC: Inventive step in practice

Our earlier article on rethinking inventive step at the UPC set out the new three-step framework for assessing inventive step before the Unified Patent Court (UPC), as crystallised by the Court of Appeal in Amgen v Sanofi and Regeneron (UPC_CoA_528/2024).

This decision provides valuable guidance for shaping inventive step strategies before the UPC. In this article, we explore practical lessons arising from the judgment, consider where the UPC’s approach truly diverges from the EPO’s, and discuss the implications for patent drafting and prosecution.

Amgen v Sanofi/Regeneron: a more demanding approach to “reasonable expectation of success”

The patent at issue (EP3666797) concerns monoclonal antibodies binding to the catalytic domain of PCSK9 for use in treating hypercholesterolaemia. The Central Division had revoked the patent for lack of inventive step starting from Lagace (a 2006 publication expressly suggesting that “the development of antibodies to block [PCSK9’s] interaction with the LDLR… can be explored for the treatment of hypercholesterolemia”). The UPC Court of Appeal disagreed, reinstating the patent.  Several aspects of its reasoning are particularly instructive.

The Court of Appeal accepted that the skilled person had a “strong incentive” to block PCSK9 activity. It also accepted that antibody generation against PCSK9 was routine. However, neither consideration was determinative. The critical question was whether the skilled person, at the filing date, could rationally predict that such antibodies would successfully deliver the therapeutic benefit. The relative contribution of PCSK9’s intracellular and extracellular pathways remained unresolved at the priority date, and without that knowledge, antibody therapy (which can only act extracellularly) carried real scientific uncertainty.

The Court of Appeal was prepared to accept that the skilled person could have developed candidate antibodies at the priority date with a hope of succeeding. That, however, falls short of the standard required. The Court of Appeal explicitly framed the distinction: a reasonable expectation of success requires “the ability of the skilled person to predict rationally, on the basis of scientific appraisal of the known facts before a research project was started, the successful conclusion of that project within acceptable time limits”.

The judgment confirms that strong commercial motivation, a clearly identified target, and routine techniques to address that target are not, in combination, sufficient to render a claimed solution obvious where the underlying biology, and therefore the likelihood of therapeutic success, is not yet settled.

For patentees, this provides a valuable evidential framework. Demonstrable gaps in the scientific understanding at the priority date may be sufficient to negate an otherwise compelling obviousness argument.

Contemporaneous industry activity is not determinative

Sanofi argued that several pharmaceutical companies were already developing anti-PCSK9 antibodies before the priority date, and that this evidenced a reasonable expectation of success. The Court of Appeal rejected this argument, observing that “the fact that other persons or teams were working contemporaneously on the same project does not necessarily imply that there was a reasonable expectation of success. It may also indicate that it was an interesting area to explore with a mere hope to succeed.” Practitioners should not assume that industry interest is, in itself, persuasive evidence of obviousness.

The Court of Appeal also confirmed an important evidential principle. Where a patentee identifies and substantiates relevant technical or practical uncertainties, the burden shifts to the challenger to demonstrate that those uncertainties would not have prevented the skilled person from having a reasonable expectation of success. In Amgen’s case, the unresolved relative contribution of the two PCSK9 pathways was sufficient to engage that shift. For patentees, this is a powerful procedural tool: substantiated uncertainty is not merely persuasive evidence, it actively reallocates the evidential burden.

“Therapeutic effectiveness” as an implicit feature of medical use claims

As the claim was drafted in a medical-use format, the Court of Appeal held that therapeutic effectiveness is an inherent feature of the claim. The implication is twofold. First, for inventive step, a challenger must show that the skilled person would have had a reasonable expectation not merely of some measurable biochemical effect, but of “a noticeable improvement of the medical condition of the patient suffering from the disease mentioned in the claim” i.e. a clinically meaningful therapeutic effect. Second, for claim construction, this implicit feature limits the scope of the claim to embodiments that are objectively suitable for the claimed therapeutic use.

Importantly, the Court of Appeal stopped short of imposing any specific quantitative threshold for what constitutes a “meaningful” effect, confirming that “the claims do not require any particular threshold regarding the level of therapeutic effect that the claimed product must achieve, as long as it is therapeutically effective in a meaningful way”.

Ideally, where a medical-use claim is to be defended before the UPC (and indeed the EPO), the application should preferably contain in vivo demonstrating a therapeutic effect or at least a robust pharmacological correlate of one. If such data is unavailable, the applicants may rely on an established scientific rationale. However, this may increase the inventive step threshold.

Does the UPC framework produce different outcomes to the EPO?

The EPO Opposition Division rejected Sanofi’s and Regeneron’s opposition in May 2025 and upheld the patent as granted; an appeal to the Technical Board of Appeal is pending.

The UPC’s holistic framework for assessing the inventive concept as a whole diverges from the EPO’s problem-solution approach in methodology, but the substantive outcomes are likely to converge in most cases.

To discuss your IP strategy or the implications of recent UPC decisions for your portfolio, please contact us at gje@gje.com.