US Federal Circuit reinstates Teva’s patent on anti-CGRP headache drug in case against Eli Lilly

Teva Pharmaceuticals International GmbH and Teva Pharmaceuticals USA, Inc. (Israel) received a reversal from the US Court of Appeals for the Federal Circuit on April 16, 2026, reinstating jury findings that Eli Lilly and Company (US) willfully infringed three US patents covering methods of using humanized anti-CGRP antagonist antibodies to treat headache. The decision, which reversed a judgment as a matter of law entered by the US District Court for the District of Massachusetts, turns on whether Teva’s patent specifications adequately described and enabled a genus of humanized monoclonal antibodies targeting calcitonin gene-related peptide — a neuropeptide whose binding to vascular receptors drives the vasodilation and trigeminovascular activation associated with migraine.

The patents at issue — US Patent Nos. 8,586,045, 9,884,907, and 9,884,908, collectively termed the “headache patents” by the court — carry a November 2006 priority date and claim methods of reducing the incidence of or treating headache by administering a humanized anti-CGRP antagonist antibody. The specification discloses a single humanized antibody, G1—the active ingredient in fremanezumab (Ajovy), approved by the US FDA in September 2018.

Context and competitive landscape

The Teva v. Eli Lilly Federal Circuit ruling arrives in a migraine prevention market that has been defined since 2018 by a cluster of anti-CGRP monoclonal antibodies, each differentiated by molecular target, dosing interval, and route of administration.

The closest mechanistic comparator within Lilly’s portfolio is galcanezumab (Emgality), a humanized antibody approved by the US FDA in September 2018 for migraine prevention and, subsequently, for episodic cluster headache. Like fremanezumab, galcanezumab binds the CGRP ligand rather than its receptor, blocking downstream receptor activation and the trigeminovascular signaling cascade implicated in migraine pathophysiology. A Massachusetts jury found Lilly willfully infringed through Emgality’s commercialization—a finding the Federal Circuit now restores after the district court’s post-trial invalidation.

A second ligand-directed peer is eptinezumab (Vyepti), a humanized anti-CGRP monoclonal antibody developed by Lundbeck (Denmark) and administered intravenously on a quarterly basis. Eptinezumab received US FDA approval in February 2020 for preventive treatment of migraine in adults. Its intravenous delivery distinguishes it from the subcutaneous administration routes used by fremanezumab and galcanezumab, but its mechanism of peripheral CGRP ligand neutralization places it within the same pharmacological class implicated by Teva’s patent claims.

The class also includes erenumab (Aimovig), developed jointly by Amgen (US) and Novartis (Switzerland), which takes a distinct mechanistic approach by targeting the CGRP receptor rather than the ligand itself. Erenumab was the first anti-CGRP pathway antibody to receive US FDA approval, in May 2018. Because erenumab binds the canonical CGRP receptor rather than CGRP itself, it does not fall within the literal scope of claims directed to anti-CGRP antagonist antibodies, though it competes for the same preventive migraine patient population. The distinction between ligand-directed and receptor-directed strategies has been a recurring axis of differentiation in both clinical positioning and patent claim construction across this therapeutic class.

The Federal Circuit’s written description and enablement analysis in the Teva v. Eli Lilly pharmaceutical patent litigation has implications that extend beyond the immediate parties. The Federal Circuit applied established precedent distinguishing between: claims to a novel genus itself, which require disclosure of representative species or shared structural features; and claims that use a known genus as part of a different invention.

Because anti-CGRP antagonist antibodies—and methods for generating them—were, by Lilly’s own inter partes review arguments, well known by November 2006, and because antibody humanization was routine at the time, the court held that a reasonable jury could find Teva’s disclosure sufficient.

The court contrasted its reasoning with the US Supreme Court’s decision in Amgen Inc. v. Sanofi, where claims to a functionally defined genus of anti-PCSK9 antibodies were held not enabled. The headache patents, in the Federal Circuit’s analysis, do not claim the genus of humanized anti-CGRP antagonist antibodies for all purposes; they claim only the use of such antibodies for the specific, limited purpose of treating headache — a purpose the specification disclosed all members of the genus would serve. That distinction, grounded in the court’s reading of prior precedent including Ajinomoto Co. v. ITC and In re Herschler, provided the analytical basis for reversing the District Court of Massachusetts appeal outcome and remanding for further proceedings. Costs were awarded to Teva. Specific clinical results for any cohort beyond the approved Ajovy label remain undisclosed in the court record.