Federal Circuit Breathes New Life into Methods Claiming Use of an Antibody Genus

The Federal Circuit’s decision in Teva Pharmaceuticals v. Eli Lilly & Co. (Appeal No. 24-1094) clarifies how Patent Act Section 112’s written description and enablement requirements apply to methods of using antibodies.

Eli Lilly challenged six of Teva’s patents claiming either humanized anti-CGRP antagonist antibodies (the antibody patents) or methods of using those antibodies to treat headache (the headache patents) through several inter partes reviews (IPRs). While the Patent Trial and Appeal Board found the antibody patents unpatentable, it found the headache patents patentable. The Federal Circuit affirmed these decisions.[1]

Teva separately sued Eli Lilly in the District Court for the District of Massachusetts, alleging that Eli Lilly’s product Emgality® infringed the headache patents. The jury sided with Teva, finding that Eli Lilly had infringed and failed to prove the patents invalid for failure to comply with the written description and enablement requirements. The district court did, however, grant judgment as a matter of law (JMOL) of invalidity on written description and enablement. Teva appealed, and the Federal Circuit reversed the grant of JMOL, reinstating the jury’s verdict.

THE HEADACHE PATENTS

The headache patents claim methods of treating headaches in a human by “administering to the human an effective amount of an anti-CGP antagonist antibody, wherein said anti-CGRP antagonist antibody is a . . . humanized monoclonal antibody.” The specification explains that anti-CGP antagonist antibodies were “known in the art,” but did not itself disclose the sequences of the anti-CGP antagonist antibodies.

Further, despite the specification disclosing various murine anti-CGRP antagonist antibodies, it only disclosed one humanized anti-CGRP antagonist antibody. Eli Lilly argued the specification did not disclose a representative number of species of the asserted claims’ genus—which encompassed only humanized anti-CGRP antagonist antibodies.

COURT DIFFERENTIATES BETWEEN ANTIBODY GENUS CLAIMS AND METHODS OF USING SUCH ANTIBODIES

The Federal Circuit’s analysis distinguishes claims to a new genus from method claims that requires using a well-known genus. The court emphasized that the “headache patents make clear that their claimed invention is the use of anti-CGRP antagonist antibodies, or humanized versions thereof, to treat headache—not such antibodies themselves.”

Citing Ajinomoto Co. v. ITC, [2] In re Herschler, [3] and In re Fuetterer, [4] the court explained that background knowledge can provide necessary written description and enablement support for such methods.

The Federal Circuit also noted how Eli Lilly’s statements during the IPR proceedings supported the jury’s findings. Eli Lilly had acknowledged the anti-CGP antagonist antibodies were “well known” and “extensively described” in the prior art. In its view, a reasonable jury could have found that humanization of murine antibodies was routine based on Eli Lilly’s statement that humanization “was a well-established and routine procedure.”

The court also observed that the specification demonstrated how to humanize antibodies using prior art methods, which likewise would have allowed a jury to view such methods as routine.

INVENTORS MAY CLAIM USING ‘WELL KNOWN’ GENUS OF ANTIBODIES AS PART OF DIFFERENT INVENTION

The Federal Circuit rejected Eli Lilly’s argument that distinguishing antibody patents and headache patents was merely a “semantic distinction without a difference.”

The court found that, unlike in University of Rochester v. G.D. Searle [5] and Ariad Pharmaceuticals v. Eli Lilly [6] —where the claimed methods lacked disclosure of usable compounds or molecules—the claims here were not for “methods of antagonizing CGRP using humanized antibodies that antagonize CGRP.” Instead, the headache patents claimed methods of treating headaches using these antibodies, which is distinct from the function that characterizes the antibodies themselves.

The court also dismissed Eli Lilly’s argument that the claims lacked written description because all disclosed anti-CGRP antagonist antibodies bind to only one of three regions. According to the court, a reasonable jury could have found that all humanized versions of such antibodies are effective in treating headaches.

ENABLEMENT CAN BE SATISFIED BY SHOWING ALL GENUS MEMBERS ACHIEVE THE CLAIMED FUNCTION

While written description and enablement are distinct, the Federal Circuit noted they often “rise and fall together,” as seen in this case. The court dismissed Eli Lilly’s argument that the claims amounted to a “research assignment” for others to create and test antibodies to determine which ones would antagonize CGRP, suggesting undue experimentation. Such an argument might have been compelling if the claims were for the genus of antibodies themselves, similar to the Supreme Court’s decision in Amgen v. Sanofi. [7]

In this context, the “research assignment” would have involved “determining which humanized anti-CGRP antagonist antibodies treat headaches.” The court noted that since the specification disclosed that all anti-CGRP antagonist antibodies treat headaches, the inventors had already completed this task. Because these antibodies were well known and all effectively treat headaches, finding or making all of them would be more akin to extra credit than a necessary research assignment left for others.

KEY TAKEAWAYS

• Using well-known antibody genera in method claims can meet the written description requirement when the inventive step lies in the method, not the genus itself.
• If the specification shows that a representative number of the genus members will achieve the claimed result, the claims are adequately enabled.

LOOKING AHEAD

The Federal Circuit’s decision offers valuable guidance for patent owners and applicants in the pharmaceutical and biotechnology sectors.

When claiming methods using a well-known genus, patentees can rely on background knowledge and routine procedures to satisfy written description and enablement requirements so long as the specification demonstrates that all genus members will achieve the claimed result.