On April 16, 2026, a Federal Circuit panel in Teva Pharms. Int'l GmbH v. Eli Lilly & Company, No. 24-1094, held that patent claims directed to methods of treating headache using a certain genus of antibodies satisfied the written description and enablement requirements of 35 U.S.C. Section 112. In so holding, the Federal Circuit distinguished the Supreme Court's 2023 Amgen v. Sanofi decision (598 U.S. 594) on the ground that a method-of-treatment (MOT) claim reciting the use of a genus of antibodies differs from a composition-of-matter (COM) claim to the genus itself.
Teva suggests that, after Amgen, such MOT claims may survive Section 112 invalidity challenges where the recited antibody genus is well known in the art and its class effect in the claimed MOT is undisputed.
Background
The patents at issue in Teva claimed methods "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." Although the patents disclosed only one such antibody species-the active ingredient in Teva's AjovyR product-the patents stated that such antibodies were known in the art and could be humanized using routine procedures. Lilly did not dispute those statements.
After trial in the District of Massachusetts, a jury returned a verdict in Teva's favor on patent infringement and validity. However, the district court granted Lilly judgment as a matter of law (JMOL) of invalidity for lack of written description and enablement. On appeal, the Federal Circuit reversed JMOL, emphasizing the difference between patent claims reciting a "well-known genus used as part of a different invention" and patent claims to the genus itself.
Written Description
On written description, the Federal Circuit explained that it and its predecessor court had previously rejected written description invalidity challenges "where a claim pertains to a well-known genus that is not, itself, the invention." That precedent included Ajinomoto Co. v. ITC, 932 F.3d 1342 (Fed. Cir. 2019), wherein the invention concerned enhancing the activity of a particular gene using a "more potent promoter" to increase production of particular amino acids, and In re Herschler, 591 F.2d 693 (CCPA 1979), wherein the invention concerned enhancing skin penetration of a "physiologically active steroidal agent" using the chemical DMSO.
Analogizing to those cases, the Federal Circuit in Teva held that "the claimed invention is the use of anti-CGRP antagonist antibodies, or humanized versions thereof, to treat headache-not such antibodies themselves." (emphasis in original). And as with the "more potent promoter" genus in Ajinomoto and the "steroidal agent" genus in Herschler, the Federal Circuit in Teva concluded that the genus of anti-CGRP antagonist antibodies, and procedures for humanizing them, were well known in the prior art. The Federal Circuit further noted it was undisputed that "a reasonable jury could have found that a skilled artisan would have understood from the specification that all humanized anti-CGRP antagonist antibodies treat headache."
The Federal Circuit distinguished other written description decisions, namely Ariad Pharms., Inc. v. Eli Lilly & Co., 598 F.3d 1336 (Fed. Cir. 2010) (en banc) and Univ. of Rochester v. G.D. Searle & Co., 358 F.3d 916 (Fed. Cir. 2004), on the grounds that in those cases, no compounds were adequately disclosed by the patents or the prior art to achieve the claimed uses, and moreover that the claims in those cases recited uses for the compounds that "could not fairly be considered part of a different invention."
Enablement
On enablement, the Federal Circuit noted that the Teva case "would resemble Amgen" if Teva's claims were "to the genus of humanized anti-CGRP antagonist antibodies themselves." But the Federal Circuit again distinguished Teva's MOT claims, framing the relevant enablement inquiry as whether a skilled artisan would have had to undertake undue experimentation, in the form of a "painstaking" trial-and-error "research assignment," to determine "which humanized anti-CGRP antagonist antibodies treat headache." (emphasis in original).
The Federal Circuit answered that question in the negative, reasoning that Teva's claims were enabled because:
[t]hat assignment was completed; the [patent] specification disclosed that all such antibodies work for that purpose. Given that anti-CGRP antagonist antibodies (and methods of making them) were already well known, humanizing them would have been routine, such humanized antibodies themselves are not claimed here, and all of them work in the claimed method, undertaking to find or make all of them would-in the context of these claims-be more akin to extra credit than a necessary research assignment left to others to complete. (emphasis in original)
In reaching that conclusion, the Federal Circuit distinguished the non-enablement holding for the MOT claims at issue in Idenix Pharms. LLC v. Gilead Scis. Inc., 941 F.3d 1149 (Fed. Cir. 2019), explaining that, unlike in Idenix, in Teva "it is undisputed that a reasonable jury could have found that all humanized anti-CGRP antagonist antibodies treat headache, thereby obviating any extensive screening to determine which ones do."