IP / Regulatory Law Watch Teva Pharmaceuticals Int’l GmbH v. Eli Lilly & Co. U.S. Court of Appeals for the Federal Circuit – Decided: April 16, 2026 Case Overview Teva Pharmaceuticals sued Eli Lilly for willfully infringing three patents (the “headache patents”) covering methods of treating headaches using humanized anti-CGRP antagonist antibodies. The active ingredient in Teva’s product Ajovy is one such antibody (“G1”). Eli Lilly’s product, Emgality, also uses a humanized anti-CGRP antagonist antibody, and a jury found Eli Lilly liable for willful infringement. However, the U.S. District Court for the District of Massachusetts granted Judgment as a Matter of Law (JMOL), invalidating the patents for failing to meet two requirements under 35 U.S.C. § 112. The Federal Circuit reversed, reinstating the jury verdict in Teva’s favor, and remanded for further proceedings. The “Headache Patents” – U.S. Patent Nos. 8,586,045; 9,884,907; and 9,884,908 (priority date: November 2006), claiming methods of treating headache using humanized anti-CGRP antagonist antibodies The Intellectual Property Law at Issue: 35 U.S.C. § 112 The central legal dispute involved two distinct requirements embedded in 35 U.S.C. § 112 (the patent specification statute), both of which Eli Lilly argued Teva’s patents failed to satisfy: 1. Written Description Requirement A patent’s specification must reasonably convey to a person of ordinary skill in the art that the inventors actually possessed the full scope of the claimed invention at the time of filing. For patents claiming a genus (a broad category) of compounds, this means disclosing either a representative number of species within the genus, or structural features common to all members. Eli Lilly argued that because Teva’s patents disclosed only one humanized anti-CGRP antagonist antibody (G1), they failed to adequately describe the entire genus of such antibodies claimed. The Federal Circuit disagreed, holding that where the genus itself (anti-CGRP antagonist antibodies) was already well known in the prior art, and humanization was a routine procedure, the specification’s disclosures were sufficient. The court relied on the principle that a well-known genus used as a component of a different invention requires less disclosure than a novel genus being claimed for the first time. 2. Enablement Requirement A patent’s specification must also teach those skilled in the art how to make and use the full scope of the claimed invention without undue experimentation. Eli Lilly argued that the enormous number of potential antibody candidates and the screening required to identify which ones antagonize CGRP amounted to an impermissible “research assignment” left to others. The Federal Circuit again sided with Teva, distinguishing the claims here (methods of using such antibodies to treat headache) from prior cases like Amgen v. Sanofi (2023), where the claims were to the antibodies themselves. Because all humanized anti-CGRP antagonist antibodies were shown to treat headache, no extensive screening was needed — the research assignment had already been completed. Outcome & Significance The Federal Circuit reversed the district court’s JMOL and reinstated the jury’s verdict of willful infringement. The decision reinforces an important distinction in patent law: when a patent’s invention is a new use of a well-known class of compounds (rather than the compounds themselves), the written description and enablement standards are applied with more flexibility. This ruling has notable implications for the pharmaceutical industry, particularly in biologics and antibody-based therapies, where broad genus claims are common and the line between claiming a compound and claiming its use is frequently litigated. Costs were awarded to Teva. For more: | 
