IP Law Daily, PATENT—Fed. Cir.: Validity of Teva Pharma’s migraine antibody patents reinstated, judgment for Eli Lilly reversed, (Apr 17, 2026)

By Saurabh Kashyap, B.A., M.A., LL.B., LL.M.

A reasonable jury could find that the asserted patents satisfied the written description and enablement requirements for methods using well-known antibodies.

The U.S. Court of Appeals for the Federal Circuit has reversed and remanded the District of Massachusetts’ judgment as a matter of law (JMOL), invalidating Teva Pharmaceuticals’ migraine treatment patents, holding that a reasonable jury could have found that Eli Lilly failed to prove lack of written description and enablement by clear and convincing evidence. The appellate court reinstated the jury’s verdict that Lilly willfully infringed the asserted claims and did not establish invalidity, concluding that the district court improperly displaced jury-supported factual findings regarding the state of the art, the nature of the invention, and the sufficiency of the specification (Teva Pharmaceuticals International GmbH v. Eli Lilly and Co., No. 24-1094 (Fed. Cir. Apr. 16, 2026)).

Background. The plaintiffs-appellants, Teva Pharmaceuticals International GmbH and Teva Pharmaceuticals USA, Inc., are pharmaceutical companies engaged in the development of biologic therapies, including migraine treatments based on calcitonin gene-related peptide (CGRP) inhibition. The defendant-appellee, Eli Lilly and Company, is a competing pharmaceutical manufacturer that markets its own CGRP-targeting migraine therapy, Emgality.

The litigation involved three Teva patents—U.S. Patent Nos. 8,586,045 (the ’045 patent), 9,884,907 (the ’907 patent), and 9,884,908 (the ’908 patent)—collectively referred to as the “headache patents.” These patents claimed methods of treating headaches in humans by administering an effective amount of a humanized monoclonal anti-CGRP antagonist antibody. The specification explained that CGRP plays a role in headache by increasing blood flow, and that antibodies can bind to and inhibit CGRP. It disclosed several murine anti-CGRP antibodies, described methods for humanizing such antibodies, and indicated that these antibodies could be used to treat headaches. Although only one specific humanized antibody was expressly identified, the specification incorporated prior-art techniques and background knowledge concerning antibody development and humanization.

Teva filed this lawsuit in 2018, alleging that Lilly indirectly infringed the headache patents through its Emgality product. After the trial, the jury returned a verdict in Teva’s favor, finding that Lilly willfully infringed the asserted claims and failed to prove them invalid. The jury awarded damages based on that finding. Lilly moved for JMOL, arguing that the patents were invalid for lack of written description and enablement under 35 U.S.C. § 112. The district court granted the motion, concluding that the specification did not adequately describe the full scope of the claimed genus of humanized anti-CGRP antibodies and required undue experimentation to practice. Teva appealed, contending that the district court improperly substituted its own judgment for that of the jury on disputed factual issues.

Written description. The Federal Circuit held that the district court erred in overturning the jury’s finding that the written description requirement was satisfied. Reaffirming the governing standard, the court explained that the specification must demonstrate that the inventors possessed the claimed invention at the time of filing, as understood by a person of ordinary skill in the art, relying on Ariad Pharms., Inc. v. Eli Lilly & Co., 598 F.3d 1336, 1351 (Fed. Cir. 2010).

The appellate court emphasized that the claims were directed to a method of treatment, not to the antibodies themselves. In that context, the relevant inquiry was whether the specification adequately described the use of a known class of antibodies to treat headache. Substantial evidence supported the jury’s finding that anti-CGRP antagonist antibodies were well known in the prior art, that methods of making them were established, and that humanization techniques were routine by the priority date.

Drawing on precedent addressing inventions that employ known genera, the court explained that a specification need not enumerate numerous species where the claimed invention lies in applying a known class of compounds in a new way, as recognized in Ajinomoto Co. v. ITC, 932 F.3d 1342, 1359 (Fed. Cir. 2019). Here, the specification disclosed several murine antibodies, described humanization methods, and indicated that such antibodies could be used to treat headaches. Viewed in light of the background knowledge in the field, the jury could reasonably conclude that the disclosure demonstrated possession of the claimed method.

The court rejected Lilly’s argument that the absence of multiple humanized antibody examples rendered the patents invalid. It held that the jury could reasonably find that humanization was a routine step, and that disclosed murine antibodies were only a predictable step away from the claimed humanized antibodies. Differences in antibody structure or binding regions did not undermine the adequacy of the disclosure because those differences did not affect the relevant functional property—treatment of headache.

Enablement. The Federal Circuit likewise reversed the district court’s finding of lack of enablement, reiterating that the specification must teach a skilled artisan to make and use the claimed invention without undue experimentation, with the scope of enablement commensurate with the claims.

The court distinguished cases involving claims to entire classes of compounds, noting that in Amgen Inc. v. Sanofi, 598 U.S. 594 (2023), the Supreme Court held broad genus claims invalid where their full scope would require extensive trial-and-error screening. Unlike those claims, the patents at issue here were limited to a method of using a known class of antibodies, not to the antibodies themselves.

Although the court assumed that identifying all possible anti-CGRP antibodies might require significant effort, it held that such an undertaking was not necessary to practice the claimed method. The jury could reasonably find that all humanized anti-CGRP antagonist antibodies would perform the claimed function of treating headaches, thereby eliminating the need for extensive screening to determine which candidates would be effective.

The court also distinguished Idenix Pharms. LLC v. Gilead Scis. Inc., 941 F.3d 1149, 1156 (Fed. Cir. 2019), where enablement failed because the specification did not identify which compounds would work, leaving a substantial research burden to others. In contrast, the record here supported the jury’s finding that the claimed class uniformly achieved the intended therapeutic result, making any required experimentation neither extensive nor undue.

Deference to jury findings. The Federal Circuit emphasized that JMOL is appropriate only where no reasonable jury could have reached the verdict on the evidence presented. The jury heard competing expert testimony regarding the state of the art, the routine nature of antibody humanization, and the functional properties of anti-CGRP antibodies. Because invalidity must be proven by clear and convincing evidence, the appellate court held that the district court erred in reweighing the evidence and substituting its own conclusions for those of the jury. Accordingly, substantial evidence supported the jury’s findings on both written description and enablement, the JMOL ruling could not stand.

Conclusion. Thus, the Federal Circuit reversed the district court’s JMOL ruling and remanded the case for further proceedings, effectively reinstating the jury’s verdict in favor of Teva on infringement and validity.

The Case is No. 24-1094.

Judge: Prost, S.

Attorneys: Kevin P. Martin (Goodwin Procter LLP) for Teva Pharmaceuticals International GmbH and Teva Pharmaceuticals USA, Inc. William Barrett Raich (Finnegan, Henderson, Farabow, Garrett & Dunner, LLP) for Eli Lilly and Co.

Companies: Teva Pharmaceuticals International GmbH; Teva Pharmaceuticals USA, Inc.; Eli Lilly and Co.

MainStory: TopStory Patent FedCirNews GCNNews