EPO Upholds, UPC Revokes: A Tale of Diverging Views on PCSK9 Antibody Patent

PCSK9 inhibitors have revolutionised cardiovascular treatment by targeting the protein that degrades LDL receptors, thus lowering “bad” cholesterol levels. This transformative impact has led to intense patent scrutiny, with major litigations focusing on what is new, what was already known, and whether it was all “obvious to try.” 

In this article, we spotlight two recent decisions - one from the Unified Patent Court (UPC) Sanofi-Aventis Deutschland GmbH, Sanofi Winthrop Industrie S.A., Sanofi-Aventis Groupe v. Amgen, Inc - and the corresponding EPO decision that addressed the same patent and grounds of challenge yet arrived at opposite conclusions on validity.

Added Matter & Priority

Both the EPO and the UPC concluded that the patent did not extend beyond its original filing. They found that the patent’s focus on binding the PCSK9 catalytic domain was supported by disclosures in the priority documents, ensuring no impermissible broadening of claim scope.

Sufficiency of Disclosure

Neither the EPO nor the UPC found a fatal flaw in how the patent instructed skilled persons to produce and screen appropriate antibodies. From immunization to phage display, from mutagenesis to crystallography, the patent set forth a range of techniques to confirm binding to the catalytic domain and predict in vivo efficacy.

Novelty

Both the EPO and the UPC agreed on novelty once the patent’s early priority date was secured, which excluded key prior-art references from invalidating the invention.

Inventive Step: The Major Divergence

• EPO: Concluded that blocking PCSK9 extracellularly was not straightforward at the relevant time. While prior art hinted at the importance of PCSK9 in LDL receptor regulation, the EPO saw no clear road map to indicate a “reasonable expectation” of success.
• UPC: Concluded the reverse. The UPC reasoned that given the wealth of available antibody-generation methods and strong motivation to inhibit PCSK9, it would have been obvious for a skilled person to try creating therapeutic antibodies.

Why the Divergence?
Decisions turned on how each body assessed “obvious to try” versus “reasonable expectation of success.” The EPO placed weight on possible uncertainties (e.g., pH conditions, specificity, in vivo efficacy) that made success less predictable. The UPC concluded, however, that these were routine challenges, not a barrier to obviousness.

Reflection

For biotech companies and patent practitioners, this case underscores that seemingly minor variations in how different courts interpret “inventive step” can result in outright opposite outcomes. Strategic foresight needs to factor in each jurisdiction’s approach to evidence, expert testimony, and nuanced questions of plausibility.

Takeaway

When defending or opposing high-stakes patents, always consider how a tribunal balances the likelihood of success versus routine challenges. Even the same facts can look “non-obvious” or “entirely foreseeable,” depending on the forum.