The U.S. Court of Appeals for the Federal Circuit has affirmed a decision that provides pharmaceutical and life sciences companies with a new strategy to challenge patent validity. In the recent Xencor Inc. case, the court upheld the Patent Trial and Appeal Board's (PTAB) rejection of Xencor's antibody patent application due to inadequate written description in its Jepson claim format.
Federal Circuit Reinforces Written Description Requirements
The Federal Circuit ruled that the preamble of a Jepson claim—which specifies prior art and describes how the claimed invention improves upon it—must be supported by sufficient written description in the patent specification. The court specifically examined Xencor's claim preamble that stated: "In a method of treating a patient by administering an anti-C5 antibody with an Fc domain, the improvement comprising."
Both the PTAB and Appeals Review Panel (ARP) found that Xencor's specification failed to provide adequate support for the broad genus of anti-C5 antibodies claimed. The specification also lacked description of what patients or diseases could be treated with the claimed antibodies and provided no working examples.
"The invention is not only the claimed improvement, but the claimed improvement as applied to the prior art, so the inventor must provide written description sufficient to show possession of the claimed improvement to what was known in the prior art," the court explained in its decision.
Building on Amgen v. Sanofi Precedent
This ruling follows the Supreme Court's significant 2023 decision in Amgen Inc. v. Sanofi, which clarified the enablement requirement for written descriptions of antibodies. In that case, the Supreme Court concluded that Amgen's broad claims to antibodies based on their function were not enabled by the examples provided in the patent.
The Supreme Court rejected Amgen's argument that its claims were enabled because a skilled person could find functional antibodies through making and testing new antibodies. The Court characterized this approach as "simply requiring others to undertake their own research projects, not enabling them to make and use the full scope of claimed antibodies."
Implications for Pharmaceutical Patent Strategy
The combined impact of the Amgen and Xencor decisions creates significant challenges for life sciences companies seeking patent protection for complex biological inventions. Companies filing patent applications must now provide more detailed written descriptions and enabling disclosures, especially when making broad claims involving biological materials like antibodies.
Dr. Sarah Johnson, a patent attorney specializing in life sciences, notes: "These rulings raise the bar substantially for biologic patent applications. Companies now need to demonstrate not just theoretical utility but practical applications with specific examples covering the full scope of their claims."
New Vulnerabilities for Patent Challengers to Exploit
For companies looking to challenge drug patents listed in the FDA's "Orange Book," the Xencor decision adds another vulnerability to explore. Patent challengers should now examine whether patents describe how to make and use the full scope of claims, and whether they include sufficient background information commensurate with the complexity of the relevant art.
The ruling emphasizes that patents must include sufficient description to demonstrate that the patentee actually invented the entire breadth of what they're claiming. Patents that rely on limited examples to show possession of a broad, unpredictable area are particularly vulnerable to written description and enablement challenges.
Strategic Considerations for Life Sciences Companies
Life sciences companies must now carefully consider their patent application strategies in light of these decisions. For patent applicants, this means:
- Providing comprehensive written descriptions with specific examples
- Ensuring claims are commensurate with the scope of the examples provided
- Including detailed information about patient populations and treatment methods
- Demonstrating practical applications beyond theoretical utility
For companies challenging patents, the Xencor decision offers a new avenue to scrutinize patents for potential written description deficiencies, particularly in Jepson claim formats that rely on characterizations of prior art.
The Federal Circuit's decision ultimately reinforces that the level of detail required in patent applications "varies depending on the nature and scope of the claims and on the complexity and predictability of the relevant technology," with biologic products like antibodies facing particularly stringent requirements.
