Key Points

• In Teva Pharmaceuticals International GmbH v. Eli Lilly & Co., the Federal Circuit upheld broad method of treatment claims directed to using anti-CGRP antagonist antibodies to treat headache, even though corresponding composition claims had been invalidated.
• For method claims, the court held that the written description and enablement inquiries under 35 U.S.C. § 112 focus on the claimed use — not the genus of antibodies themselves. The requirements may be satisfied when the genus includes well-known molecules or molecules that could be generated by routine techniques.
• The decision confirms a path toward broader patent protection for therapeutic antibodies, with implications for new applications and existing portfolios.

The Federal Circuit recently held in Teva Pharmaceuticals International GmbH v. Eli Lilly & Co., No. 2024-1094 (Fed. Cir. 2026) that patent claims directed to treating a specific disorder with a broad genus of antibodies were not invalid.

This decision is important because it confirms that method of treatment claims may be adequately described and enabled, even if corresponding composition claims are not. Claims directed to methods of treatment with antibodies may satisfy the written description and enablement requirements even when reciting a broad genus of antibodies defined by the binding target and without amino acid sequences.

Background

Antibody therapies are medically and commercially important. Companies that have spent years and millions of dollars to bring these drugs to market have a strong interest in maximizing their exclusivity to sell their product through intellectual property rights and regulatory exclusivities. Patents may protect the antibody molecule itself, often specifying amino acid sequences that contribute to binding. Therapeutic antibodies may also be protected by method of treatment claims, and this protection is still quite valuable because drugs must be FDA-approved for particular uses before being sold.

Among several requirements for patentability in the U.S., claims must satisfy 35 USC § 112. Under the “written description” requirement of § 112(a), the specification must describe the claimed invention in enough detail to reasonably convey that the inventors had possession of the claimed subject matter at the time of filing. Under the “enablement” requirement of § 112(a), the specification must teach one of ordinary skill to make and use the invention without undue experimentation.

In 2023, in Amgen v. Sanofi, the Supreme Court held that broad antibody claims, essentially claiming an antibody by its binding properties without describing the amino acid sequence of the protein, were not enabled. This upended years of patent practice in which such claims were routinely sought and issued. In a separate case largely paralleling the Amgen timeline, Juno Therapeutics, Inc. v. Kite Pharma, Inc., the Federal Circuit held that claims to chimeric antigen receptors with binding domains defined functionally did not satisfy the written description requirement.

These cases reflect a sea change in U.S. patent practice for biotechnology, significantly altering the types of claims typically allowed by the USPTO and considered likely enforceable by practitioners. An open question was whether method claims could fare differently than their compositional counterparts. The recent Federal Circuit decision has now provided clarity.

Procedural History and Patents at Issue

Teva had several granted patents covering its migraine drug Ajovy®. Teva sued Eli Lilly over its competing product, Emgality®, alleging induced infringement of its patents. Eli Lilly counterclaimed that Teva’s patents were invalid.

Eli Lilly successfully invalidated several of Teva’s antibody composition patents in parallel inter partes review (IPR) proceedings before the PTAB, where those claims were held unpatentable for obviousness. The method of treatment patents survived. Each IPR board decision was appealed to the Federal Circuit and affirmed.

The method patents asserted by Teva were U.S. Patent Nos. 8,586,045, 9,884,907 and 9,884,908, issued between 2013 and 2018. Claim 30 of the ‘045 patent, as rewritten by the court, is representative:

A method for reducing incidence of or treating headache in a human, comprising administering to the human an effective amount of an anti-CGRP antagonist antibody, wherein said anti-CGRP antagonist antibody is a . . . humanized monoclonal antibody.

Binding of CGRP to receptors on certain cells causes cells to expand and increase blood flow, apparently contributing to headaches. In its patents, Teva disclosed that anti-CGRP antibodies with antagonistic (inhibitory) activity could be used to treat headaches.

Although composition claims to antibodies protect all uses and are usually considered most valuable, for FDA-approved medical therapies, even somewhat narrow method of treatment claims can still offer significant protection against generics. Here, Emgality® is a different humanized anti-CGRP antagonist antibody than Ajovy®, so the breadth of the antibody limitation of the method claims was key.

The jury found that Eli Lilly failed to prove that the claims were invalid and had willfully infringed the patents. It awarded Teva $177 million. The District Court for the District of Massachusetts, however, then granted judgment as a matter of law (JMOL), overturning the verdict. Teva appealed.

Federal Circuit Decision

On appeal, the Federal Circuit reversed the District Court, vacating the JMOL and remanding the case for further proceedings consistent with its opinion.

In its analysis of the written description issue, the court focused on “whether the specification disclosed a representative number of species of the asserted claims’ genus of humanized anti-CGRP antagonist antibodies.” The court analogized the facts to several cases in which the invention was not the composition itself, but instead a new use, where the genus included well-known molecules or molecules that could be generated by well-known techniques. The court stated 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.” The court went on to conclude that a reasonable jury could find that these antibodies and methods of making them were well known, that humanization was routine by the priority date, and that a skilled artisan would understand from the specification that all such antibodies treat headache.

The court’s analysis of enablement followed a similar line of reasoning. The court also distinguished Amgen. Because the claims were limited to using antibodies for treating headache — not claiming the antibodies themselves — the relevant “research assignment” was narrower: determining which antibodies treat headache, not identifying antibody molecules. Moreover, the research assignment was already completed because “the specification disclosed that all such antibodies work for that purpose.” The court considered that finding or making all of these humanized antibodies was “more akin to extra credit.”

Takeaways

For those wondering whether any sequence-agnostic antibody claims could survive post-Amgen, the Federal Circuit’s answer is apparently yes when it comes to method claims. In considering the method claims to be directed to an invention of the use of the antibodies, and not a mere “semantic distinction” from composition claims, the court confirmed that such claims may satisfy § 112 when the genus includes well-known molecules or molecules that could be generated by routine techniques.

If the path toward patentability is clearly there for method claims, how many, if any, specific antibodies must be described to support such claims? The Teva patents disclosed several murine antibodies and a single humanized antagonistic antibody. On one hand, the written description requirement was found to be satisfied here even though the number of antibodies disclosed was much lower than in other cases in which composition claims were invalidated. On the other hand, it appears to be important that at least some antibodies be known in the art or disclosed in the specification, as the court distinguished cases where specific molecules were not disclosed at all and were described solely in functional terms.

The decision also suggests that a recited use going beyond a purely functional property is important; that is, the claims should recite a specific disease. However, a reference to a function or mechanism of action may play a role in confirming that one could reasonably conclude that the entire genus will treat the disease. The court stated that a reasonable jury could have found that a skilled artisan would have understood that all humanized anti-CGRP antagonist antibodies treat headache, and the outcome could have been different if the claim did not recite antagonistic functionality.

Another lesson relates to the tension between obviousness and § 112. To support its conclusion, the court referenced Eli Lilly’s own IPR arguments that anti-CGRP antagonist antibodies and methods of making them were well known. Arguing one side of this tension can work against you on the other.

Innovator companies will likely view this as a welcome development, confirming a path toward broader protection for therapeutic modalities in the context of methods of treating specific diseases. The invention of new uses of antibodies may allow for patent protection to be obtained without being limited to a specific antibody binding domain sequence, and thus more difficult to design around. Of course, claims must still be novel and nonobvious — hurdles that may be difficult when antibodies to the target are already known.

And for all players in the biotechnology space, the decision impacts evaluations of the existing patent landscape. By upholding broad method claims, the decision may prompt reassessment of risks associated with patents that have already been filed or issued.

For more information, please contact Brooke Sargeant at 206.389.1503 or bsargeant@foxrothschild.com, or another member of Fox Rothschild’s national Intellectual Property Department.

This information is intended to inform firm clients and friends about legal developments, including the decisions of courts and administrative bodies. Nothing in this alert should be construed as legal advice or a legal opinion. Readers should not act upon the information contained in this alert without seeking the advice of legal counsel. Views expressed are those of the authors and not necessarily this law firm or its clients.