Our Patent Case Summaries provide a weekly summary of the precedential patent-related opinions issued by the Court of Appeals for the Federal Circuit and the opinions designated precedential or informative by the Patent Trial and Appeal Board.
Duke University, et al. v. Sandoz Inc.
No. 2024-1078 (Fed. Cir. (D. Colo.) Nov. 18, 2025). Opinion by Stark, joined by Dyk and Stoll.
Duke University and Allergan Sales together own all rights in a patent directed to treating hair loss using compositions containing prostaglandin F analogs. Allergan markets Latisse®, an FDA-approved topical solution for treatment of eyelash hair loss by stimulating hair growth. Sandoz manufactures and sells a generic version of Latisse.
Allergan sued Sandoz for infringement of claim 30 of the patent. The claim describes numerous compounds—1,620 compounds per Sandoz’s expert, or 4,230 compounds per Allergan’s expert—that can cause hair to grow. Sandoz stipulated to infringement but challenged the validity of claim 30, including attempting to prove that the claim is invalid for lack of adequate written description.
At trial, a jury found Sandoz had failed to prove that claim 30 was invalid and awarded Allergan $39 million in damages. Sandoz then moved for a new trial and for judgment as a matter of law, both of which the district court denied. Sandoz appealed.
In the appeal, Sandoz argued that “the specification does not provide a single example of an actual compound claimed by claim 30 and also fails to identify sufficient commonalities of structure to provide a skilled artisan with the necessary ‘blaze marks’ to lead them to the claimed compounds.” The Federal Circuit agreed and thus reversed, holding that “no reasonable juror could have found that Sandoz failed to prove, by clear and convincing evidence, that claim 30 lacks adequate written description.”
To begin, the Federal Circuit stated that “[t]he written description requirement reflects the basic premise of the patent system: an inventor may obtain a patent only if she discloses the invention to the public, in sufficient enough detail that a person of ordinary skill in the art will understand that the inventor truly possessed the invention as claimed.” Applied here, the court ruled that based on the evidence presented, including certain information agreed to by experts on both sides, “any reasonable juror had no choice but to find that the specification broadly described billions of compounds, while claim 30 was directed to between just 1,620 and 4,230 of such compounds.”
The Federal Circuit continued: “In order to have adequate written description, the specification of the [asserted] patent needs to allow a skilled artisan to understand how to identify this subgenus of claimed compounds.” The evidence presented at trial, however, confirmed that the patent “fails to describe either (i) a representative number of species of claim 30’s subgenus or (ii) structural features common to all members of that subgenus.” Accordingly, the court ruled that “the specification fails to provide the relevant artisan with sufficient blaze marks or structural commonalities among the claimed compounds to lead her to conclude that the inventor actually possessed the claimed invention.” Thus, the Federal Circuit reversed the judgment that claim 30 was not invalid for lack of a written description.