Recitation of Common Functional Groups for Genus Claims Fails Written Description Requirement

In an opinion issued on March 6, 2023, the Federal Circuit affirmed the PTAB’s holding of unpatentability because the applications from which the patent claimed priority from lacked sufficient written description under 35 U.S.C. § 112. Regents of University of MN v. Gilead Sciences, Inc., No. 2021-2168 (March 6, 2021). Because the patent could not claim the benefit of the earlier priority date, the patent was anticipated by prior art, and therefore unpatentable.

This action stemmed from an IPR petition Gilead Sciences filed challenging the claims of U.S. Patent 8,815,830 (“the ‘830 patent”). The ‘830 patent is directed to a subgenus of cancer drugs, and claims priority from U.S. Provisional App. 60/634,677 and PCT/US2005/044442, which disclose a broader genus of cancer drugs. The PTAB held that the applications from which the ‘830 patent claims priority provided neither ipsis verbis support nor sufficient blaze marks to guide the skilled artisan to the claims of the ‘830 patent. The University of Minnesota appealed to the Federal Circuit, arguing that the applications disclosed enough species to constitute a written description of the claimed subgenus.

On appeal, the Federal Circuit found no error in the Board’s determination that there was insufficient written description in the prior applications. Specifically, the Federal Circuit stated that “written description of a broad genus requires description not only of the outer limits of the genus but also of either a representative number of members of the genus or structural features common to the members of the genus, in either case with enough precision that a relevant artisan can visualize or recognize the members of the genus.” In this case, merely reciting a “laundry list” of common organic chemical functional groups was insufficient, especially when it was unclear how many compounds fell within the described genera and subgenera. Furthermore, the Court concluded that the “maze-like path…providing multiple alternative paths” failed to guide an artisan to the subgenera claimed in the ‘830 patent, so the priority applications lacked “sufficient blaze marks” as required for § 112 support.

This case is instructive for ANDA filers and patent challengers facing broad genus claims. Patentees must define the intended result with enough specificity to either actually describe the claims or describe with enough specificity that a skilled artisan would be guided to the claimed species or subgenus. ANDA filers should closely examine priority applications to determine if there is sufficient written description to support claims in subsequent child patents.