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The U.S. Court of Appeals for the Federal Circuit recently affirmed a Delaware District Court’s patent invalidity determination – effectively erasing a $100 million-plus infringement award. See Wyeth LLC v. AstraZeneca Pharms. LP, 180 F.4th 1371 (Fed. Cir. 2026). This precedential decision provides another significant application of the Supreme Court’s enablement framework articulated in Amgen Inc. v. Sanofi, 598 U.S. 594 (2023). The ruling serves as an important reminder that a patent specification must provide the disclosure necessary to practice the claimed invention and cannot leave critical aspects of the invention to be discovered by a skilled artisan’s own knowledge and experimentation.

Background

In 2021, Wyeth LLC sued AstraZeneca, alleging that AstraZeneca’s marketing of Tagrisso® (osimertinib) induced infringement of Wyeth’s U.S. Patent Nos. 10,603,314 and 10,596,162. Following a jury trial, Wyeth obtained a verdict of infringement and damages of approximately $107.5 million. The district court subsequently granted AstraZeneca’s motion for judgment as a matter of law, holding the asserted claims invalid for lack of enablement under 35 U.S.C. § 112(a).

The asserted patents claim methods of treating gefitinib- and/or erlotinib-resistant non-small cell lung cancer (NSCLC) using irreversible EGFR inhibitors. EGFR (epidermal growth factor) is an important target in cancer chemotherapy, because it is implicated as causing uncontrolled cell growth in cancer cells. Representative claim 1 of the ‘314 patent recites a method of treatment comprising daily administration to a patient of a pharmaceutical composition comprising a “unit dosage” of an irreversible EGFR inhibitor.

The specifications of both the ‘314 and ‘162 patents identify only three exemplary drug compounds and define a “unit dosage” as “a predetermined quantity of active material calculated to produce the desired therapeutic effect . . .” However, the patents contain limited in vitro data and no in vivo studies, nor do the patents provide specific examples of a therapeutically effective human daily dosage. The patents further state that “[p]recise amounts of active ingredient required to be administered depend on the judgment of the practitioner and are peculiar to each individual.”

The Federal Circuit’s Analysis

Wyeth argued that the district court “improperly imported clinical safety and efficacy requirements into the claims.” The Federal Circuit rejected that argument. According to the Federal Circuit, the claims themselves required daily administration to a patient of a “unit dosage” capable of producing a therapeutic effect. The question was not whether the patents satisfied regulatory standards, but whether the specification “teach[es] those skilled in the art how to make and use the full scope of the claimed invention without undue experimentation.”

Applying the standard for enablement set forth in Amgen[1], the Federal Circuit emphasized that “the more one claims, the more one must enable.” The court concluded that the patents failed to satisfy that standard because they did not provide a meaningful bridge between the disclosed in vitro data and the claimed in vivo treatment regimen. Although the patents described the activity of certain compounds in laboratory testing, they did not disclose an actual therapeutically effective human daily dosage for any claimed compound, nor did they provide sufficient guidance for translating in vitro activity into the claimed daily dosing regimen in a patient.

The court’s discussion of this issue contains perhaps the most important lesson for patent prosecutors. Citing Genentech, Inc. v. Novo Nordisk A/S, 108 F.3d 1361, 1366 (Fed. Cir. 1997), the court reiterated that “[i]t is the specification, not the knowledge of one skilled in the art, that must supply the novel aspects of an invention.” In the court’s view, the patents left the critical task of translating the disclosed in vitro activity into a therapeutically effective daily dosage to the skilled artisan’s own knowledge and experimentation rather than teaching how to perform that task.

The Federal Circuit also found that the disclosures in the patent specifications undermined Wyeth’s argument that dosage selection was routine. Although Wyeth characterized the disclosed dosage ranges as conventional, the specifications acknowledge that dosage determination depends on numerous variables, that dosage selection is subject to the “judgment of the practitioner,” and that the appropriate dosage is “peculiar to each individual.” The Federal Circuit found that the patents admit that determining a claimed “unit dosage” was a complex and highly individualized task, yet provide no meaningful guidance. As the court observed, where a field is complex and unpredictable, the specification must provide correspondingly greater guidance. The patents instead provided only a starting point for further research and dose optimization.

The court additionally noted that the disclosed dosage ranges were merely “general” and “projected.” Also, trial testimony established that applying the dosage ranges to at least some disclosed compounds would result in doses exceeding maximum tolerated levels in humans. While the existence of inoperative embodiments was not itself dispositive, the court found that the patents failed to teach skilled artisans how to identify daily dosages for achieving a therapeutic effect. As a result, practicing the claimed invention would require further testing and screening to distinguish operative from inoperative embodiments across the claim scope, weighing heavily in favor of non-enablement.

Strategic Takeaways

The specification must supply the enabling disclosure. The central message of Wyeth is that enablement cannot be supplied by the knowledge of a person of ordinary skill in the art. Where claims are directed to administration of a therapeutically effective dosage to a patient, the specification should provide meaningful guidance connecting disclosed experimental results to the claimed treatment regimen. Simply disclosing in vitro activity and leaving dosage determination to the practitioner may invite an argument that the patent leaves the critical enabling work to the skilled artisan rather than teaching how to practice the invention.

In vitro data alone may not support in vivo treatment claims. Although the Federal Circuit acknowledged that method-of-treatment claims do not require clinical data or FDA-style proof of safety and efficacy, the decision illustrates the risks of claiming a human treatment regimen where the specification contains only laboratory data and provides little guidance regarding therapeutic dosing selection.

The patent specifications should not emphasize dosing complexity without providing corresponding guidance. Where a patent characterizes dosage selection as unpredictable or complex, applicants should provide working examples, dose-response data, pharmacokinetic information, or other guidance sufficient to reduce the need for further testing and screening.

Concluding Thoughts

Wyeth demonstrates that post-Amgen enablement scrutiny is not limited to antibody or biotechnology genus claims, but also extends to method-of-treatment claims. For pharmaceutical patentees, the decision underscores the importance of ensuring that the specification provides a meaningful bridge between disclosed experimental results and the claimed treatment regimen. Broad functional claims, in vitro data alone, and generalized dosage disclosures may be insufficient. Perhaps most importantly, the Federal Circuit reaffirmed a foundational enablement principle: the specification, not the skilled artisan, must teach how to practice the claimed invention without undue e

[1] In Amgen, the Supreme Court held that a patent must enable the full scope of the claimed invention without undue experimentation and that broader claims require broader enabling disclosure. Amgen Inc. v. Sanofi, 598 U.S. 594 (2023).