Executive Summary: Key Legal and Evidentiary Issues

• The dispute centered on whether Amgen’s biosimilar BEKEMV infringed Alexion’s Canadian Patent No. 2,645,810 related to the drug SOLIRIS® (eculizumab).

• Amgen admitted potential infringement but argued the patent claims were invalid due to anticipation and obviousness.

• The court analyzed whether earlier publications and patents, particularly US972 and US245, disclosed or made obvious the patented antibody sequences.

• The interpretation of scientific data, especially concerning monoclonal antibody structure and genetic sequences, was critical to claim construction.

• Expert evidence from both sides played a key role, particularly in assessing whether the patented invention was sufficiently disclosed or inventive.

• The Federal Court upheld the patent’s validity and granted an injunction and delivery-up order against Amgen until the patent expires in 2027.

Facts and outcome of the case

Background and parties involved

This case involved Alexion Pharmaceuticals, Inc. and its affiliate Alexion Pharma International Operations Limited, plaintiffs and patent holders of Canadian Patent No. 2,645,810. The patent concerns the monoclonal antibody eculizumab, marketed under the name SOLIRIS®, used to treat paroxysmal nocturnal hemoglobinuria (PNH), a rare and life-threatening blood disorder. The defendant, Amgen Canada Inc., intended to launch BEKEMV, a biosimilar version of eculizumab, and filed two New Drug Submissions with Health Canada. In response, Alexion initiated two actions under the Patent Medicines (Notice of Compliance) Regulations, claiming that BEKEMV would infringe its patent.

The patent and drug in question

The '810 Patent claims relate specifically to the structure of the antibody eculizumab, defined by unique amino acid sequences in the heavy and light chains that bind complement protein C5. This protein is key to the immune-mediated destruction of red blood cells in PNH. Alexion’s patent is set to expire in March 2027 and was the second in a trio of patents related to eculizumab. The two claims at issue were: (1) the specific antibody with defined heavy and light chains, and (2) a pharmaceutical composition comprising this antibody with a carrier.

Amgen’s defence: anticipation and obviousness

Although Amgen admitted that its product would infringe the patent if valid, it argued that the claims were invalid for two main reasons: anticipation and obviousness. It relied on prior art, particularly US Patent Application 2003/023972 (US972) and US245, a foundational patent disclosing earlier forms of anti-C5 antibodies. Amgen’s position was that these documents, especially through incorporation by reference, disclosed the same antibody sequences and methods, thereby anticipating the claimed invention. Alternatively, Amgen contended that the invention was obvious in light of prior knowledge and publications by Alexion itself and others.

The court’s analysis of anticipation

The court rejected the anticipation claim. It found that although US972 incorporated US245 by reference, the prior art did not clearly and unambiguously disclose all essential elements of the claimed invention. Specifically, while some sequences overlapped, key amino acid sequences in the patented antibody were not fully disclosed or directly derivable from the earlier documents without reverse engineering. The court emphasized that anticipation requires that a skilled person would inevitably arrive at the patented invention based on a single prior disclosure, which was not the case here.

Obviousness claim also fails

The court conducted a thorough analysis using the four-step Sanofi test for obviousness. It found that even though the scientific concepts and antibody sequences had been partially explored in prior art, there was no direct roadmap leading a person skilled in the art to the specific combination of sequences that defined eculizumab. The inventive concept lay in the precise structural configuration of the antibody, which was neither self-evident nor suggested by the earlier documents. The court also dismissed Amgen’s reliance on documents that mentioned eculizumab without disclosing its sequence, concluding that a skilled person would not be led directly and without difficulty to the invention.

Outcome and remedies

Having determined that the asserted claims were valid and infringed, the Federal Court granted judgment in favor of Alexion. It issued a declaration of infringement and an injunction preventing Amgen from making, selling, or distributing BEKEMV in Canada until the patent expires on March 15, 2027. The court also ordered Amgen to deliver up or destroy infringing products within its control, except for products exempt under the Patent Act. Costs were awarded to Alexion based on a prior agreement between the parties.

Significance of the decision

This decision reinforces the robustness of patent protections for complex biologic drugs under Canadian law. It illustrates the importance of clear and complete disclosure in prior art to establish invalidity by anticipation, and the challenges of proving obviousness in cases involving biopharmaceutical inventions. The case also highlights how expert scientific testimony and claim construction can shape outcomes in biotechnology-related patent disputes.