IP Alerts

March 9, 2023

On March 6, in Regents of the University of Minnesota v. Gilead Sciences, Inc., the Federal Circuit affirmed a decision by the Patent Trial and Appeal Board (PTAB) in an inter partes review (IPR) invalidating claims of the University of Minnesota’s U.S. Patent No. 8,815,830. This opinion is a cautionary tale for those asserting written description support for a claimed genus based on multiple dependent claims or similarly formatted disclosures.

In the appeal, the University challenged the PTAB’s holding that a prior art publication anticipated claims of the ’830 patent directed to phosphoramidate prodrugs for cancer and antiviral treatments. The parties did not dispute that the publication taught all features in the claims, but disagreed as to whether the claims were entitled to filing dates of priority documents that occurred before the asserted publication. The PTAB found that priority documents lacked written description sufficient to antedate the publication.

At issue on appeal, claim 1 of the ’830 patent recites a compound having a generic structural formula including variable moieties at different positions. The University argued that a series of multiple dependent claims in one of the priority documents provided either ipsis verbis support for claim 1 or provided “blaze marks” to guide a skilled artisan to the patented claim.

Like claim 1 of the ’830 patent, the claims of the asserted priority document recite a generic structural formula including variable moieties at different positions. However, the moieties are defined in a series of multiple dependent claims that depend on other multiple dependent claims. Many of the variable moieties are defined differently in separate multiple dependent claims. The parties characterized the priority claims as a genus and the patented claims as a subgenus.

The University asserted that selection of specific multiple dependent claimsin the priority documentprovided ipsis verbis support. The Federal Circuit disagreed, stating that “[f]ollowing this maze-like path, each step providing multiple alternative paths, is not a written description of what might have been described if each of the optional steps had been set forth as the only option.” The court likened the University’s argument to Yogi Berra’s famed but indeterminate statement “when one comes to a fork in the road, take it.”

The University alternatively asserted that claims of the priority document provided “blaze marks” that would guide one skilled in the art to claim 1 of the ’830 patent. The blaze mark concept is articulated in In re Ruschig and Fujikawa v. Wattanasin, where finding species or subgenera within a large genus is like finding blaze marks on trees in a forest. Quoting Fujikawa, the court found that the University’s priority documents did not direct one to the proposed tree in particular and did not teach the point where one should leave the trail to find it.

The University also alleged that the PTAB erred in not properly considering Ariad Pharms., Inc. v. Eli Lilly. However, the court found that the University mischaracterized Ariad as holding that merely disclosing structural features common to the members of a genus demonstrates possession of and support for the claimed genus. The court noted that Ariad requires more, i.e., a description of a claimed genus by disclosing either a representative number of species falling within the scope of the genus, or structural features common to the members of the genus, either of which must enable one of skill in the art to visualize or recognize the members of the genus.

The parties did not dispute that the priority documents lacked disclosure of a representative number of species of the patented subgenus. Regarding whether common structural features must exist between a claim and a putative priority disclosure, the court noted those features must constitute the near-entirety of the structures being compared. The court again focused on the claims of one of the priority documents and held that the multiple dependencies encompassed a significantly larger genus than claimed in the ’830 patent and did not provide sufficiently common structural features to provide adequate written description.

The court affirmed the PTAB’s holding that the prior art publication anticipated the claims of the ’830 patent because the claims were unsupported by the priority documents. Going forward, practitioners should examine whether compound multiple dependent claims or other analogous disclosures provide adequate written description of claims to a genus or subgenus.

For more information on this holding, please contact Fitch Even partner Giles Turner, the author of this alert.


Fitch Even IP Alert^®