UPC’s first revocation decision takes the EPO approach on antibody inventions a step further

In the Unified Patent Court’s (UPC) first-ever revocation decision, it has clarified its stance on the patentability of antibody inventions, aligning closely with the European Patent Office (EPO) and underscoring stark differences between European and U.S. patent law in this field. It has been well-known that the standards for patenting antibody inventions in Europe differ significantly from those in the U.S., but recent case law in both jurisdictions has brought those differences to the forefront and making apparent their opposing approaches.

The divergence became pronounced after the U.S. Supreme Court's decision in Amgen Inc. v. Sanofi. The Court ruled against Amgen’s broad antibody claims, which encompassed a genus of therapeutic antibodies targeting specific amino acid residues of PCSK9, a protein involved in cholesterol regulation. Despite Amgen providing sequences for 26 antibodies within the scope of its claims and describing methods for creating antibodies that bind to the claimed epitope, the Court surprisingly concluded that the claims lacked sufficient "enablement." The work required to realize the invention, according to the ruling, would involve excessive experimentation, akin to offering researchers "two research assignments." In the U.S., finding and testing candidate antibodies is clearly not seen as a routine task.

In stark contrast, the EPO considers the creation of antibodies against a known target to be routine work for a skilled individual in the field. This lowers the sufficiency of disclosure bar for antibody patents in Europe, where broad claims—covering epitope or functional definitions—are considered enabled. However, the EPO sets a higher standard for inventiveness: antibodies targeting a known protein are not deemed inventive unless they demonstrate "unexpected properties." Therefore, in Europe, the challenge often lies in proving that an antibody, even when defined by its sequence, demonstrates an inventive step compared to pre-existing antibodies targeting the same protein.

The UPC's first ruling in a revocation case has now cemented the EPO's position on antibody inventions and even takes it a step further. The case involved a revocation action brought by Sanofi against one of Amgen’s European patents related to PCSK9 antibodies (EP 3666797). Interestingly, the same patent is pending before the Opposition Division of the EPO with oral proceedings scheduled for March 2025. The patent in question claimed an antibody that binds to the catalytic domain of PCSK9 and blocks its interaction with the LDLR receptor - a mechanism critical in cholesterol regulation – for use in the treatment of hypercholesterolemia. Much like the U.S. Supreme Court case, Amgen's antibody was defined by its function, not by its structure. 

The UPC Central Division found the patent invalid due to a lack of inventive step, citing the scientific literature authored by Lagace. Notably, Lagace was not “the closest prior art” according to the EPO’s problem-solution approach, but a “realistic starting point”; not necessarily “the most promising”. While Lagace did not describe any antibodies binding to PCSK9, it taught that “the development of anti PCSK9 antibodies that block the LDLR:PCSK9 interaction can be explored for the treatment of hypercholesterolemia”, thereby motivating researchers in the field to develop these antibodies for the treatment of hypercholesterolemia according to the UPC. Crucially, the UPC considered that developing antibodies against known targets is routine, a view consistent with the EPO. Thus, the court concluded that Amgen's antibodies lacked an inventive step in view of Lagace.

In reaching this conclusion, the UPC interpreted Amgen’s claims in a nuanced way. The court diverged from the EPO’s classical approach, which typically limits reference to the patent’s description unless the claims are ambiguous, although we are awaiting the outcome of a pending referral to the Enlarged Board of Appeal (G1/24) on the weight to be given to the description when considering claim scope. Instead, the UPC referred extensively to the description and drawings to interpret the scope of the antibody claims. The court interpreted the term “binding to the catalytic domain” broadly, ruling that it covered antibodies that bind both to amino acid residues within the catalytic domain and potentially other regions of PCSK9. However, the court emphasized that the claims' functional limitations—such as preventing PCSK9 from binding to LDLR, but also the claimed therapeutic effect—also had to be considered.  Ultimately, the UPC interpreted the claims as covering more than the specific antibodies Amgen had exemplified in its patent, though they were not broad enough to cover all antibodies capable of binding to the catalytic domain of PCSK9.

This decision provides significant insight into how the UPC intends to handle antibody patent cases moving forward. It suggests that the UPC will adhere closely to the EPO’s framework for assessing at least the enablement requirement of antibody claims. This means that while European standards remain more lenient than in the U.S. for the breadth of antibody claims, inventors will need to demonstrate true innovation—such as "unexpected properties"—to meet the high bar for inventiveness. 

Additionally, the UPC’s decision to base its inventive step assessment on a “realistic starting point,” rather than the EPO’s traditional “closest prior art” standard, may impose even stricter requirements for demonstrating inventive steps before the UPC than before the EPO. It remains to be seen whether Amgen will appeal the Court’s decision.

While the UPC ruling may raise the bar for establishing inventiveness, it also reaffirms that broad functional and/or epitope-defined claims remain permissible under European law, provided the patent discloses at least one antibody possessing the claimed features. 

We have a long-established expertise in patenting antibodies, derivatives and other inventions in the immunological field. Should you need guidance or assistance in these areas, we welcome you to reach out at info@dcp-ip.com.