On April 16, 2026, the U.S. Court of Appeals for the Federal Circuit reversed the district court’s judgment as a matter of law (“JMOL”) finding Teva’s asserted patent claims invalid for lack of written description and enablement in Teva Pharmaceuticals v. Eli Lilly & Co. (Appeal No. 24-1094) and reinstated the jury’s verdict finding the patents valid and infringed.

The case involved Teva’s U.S. Patent Nos. 8,586,045, 9,884,907, and 9,884,908, which are directed to methods of treating headache using humanized anti-CGRP antagonist antibodies. The patents are associated with Teva’s migraine treatment Ajovy^® (fremanezumab). A jury previously found that Eli Lilly willfully infringed the asserted claims by selling its drug Emgality^® (galcanezumab-gnlm) and failed to prove them invalid. The U.S. District Court for the District of Massachusetts subsequently granted JMOL that the claims were invalid under 35 U.S.C. § 112 for lack of written description and enablement.

On appeal, the Federal Circuit reversed and remanded, holding that substantial evidence supported the jury’s verdict. With respect to written description, the court found that a reasonable jury could conclude that murine anti-CGRP antagonist antibodies and methods of making them were well known in the art, and that humanization techniques were routine. The court further found that the specification’s disclosure of a single humanized anti-CGRP antagonist antibody in addition to several murine anti-CGRP antagonist antibodies, in view of the prior art, disclosed a representative number of species for the claimed methods, given the specification’s disclosure that all humanized anti-CGRP antagonist antibodies are effective for treating headaches.

The Federal Circuit also reversed the district court’s enablement ruling, concluding that the claims, which are directed to methods of treatment rather than the antibodies themselves, did not require undue experimentation. The court emphasized that the specification disclosed that all humanized anti-CGRP antagonist antibodies were effective for treating headache, and that identifying such antibodies did not constitute an impermissible “research assignment” under the circumstances.

For both its written description and enablement analysis, the Federal Circuit noted that the asserted claims were not to the genus of humanized anti-CGRP antagonist antibodies themselves, but were instead directed to the use of such antibodies for the purpose of treating headache, a distinction that separated the facts of the instant case from prior written description and enablement cases.

The case was remanded for further proceedings consistent with the Federal Circuit’s opinion.

Teva reported U.S. sales of $295M for Ajovy^® in 2025.

For more information about these and other biosimilars, please visit BiologicsHQ.

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The authors would like to thank April Breyer Menon for her contributions to this article.