A Broad Outline of a Genus's Perimeter Is Insufficient For Written Description of the Members of the Genus

April 7, 2023

The Regents of the University of Minnesota (“Minnesota”) appealed from a final decision of the U.S. PTO Patent Trial and Appeal Board (“the Board”) holding that the claims of U.S. Patent 8,815,830 were unpatentable as anticipated. The Court of Appeals for the Federal Circuit (“the Court”) affirmed.

Gilead Sciences, Inc. (“Gilead”) filed an IPR petition challenging the claims of the ’830 patent directed to phosphoramidate prodrugs of nucleoside derivatives that prevent viruses from reproducing or cancerous tumors from growing. Representative claim 1 reads:

1. A compound of formula I


     R1 is guanine, cytosine, thymine, 3-deazaadenine, or uracil, optionally substituted by 1, 2, or 3 U; wherein each U is independently halo, hydroxy, (C1-C6)alkyl, (C3-C6)cycloalkyl, (C1-C6)alkoxy, (C3-C6)cycloalkyloxy, (C1-C6)alkanoyl, (C1-C6)alkanoyloxy, trifluoromethyl, hydroxy(C1-C6)alkyl, -(CH2)1-4P(=O)(ORw)2, aryl, aryl(C1-C6)alkyl, or NRxRy;
     R2 is halo;
     R6 and R7 are independently H or (C1-C6)alkyl; R3 is hydroxy;
     R4 is hydrogen, (C1-C6)alkyl, (C3-C6)cycloalkyl, aryl, aryl(C1-C6)alkyl, or 2-cyanoethyl;
     R5 is an amino acid;
     X is oxy, thio, or methylene;
     each Rw is independently hydrogen or (C1-C6)alkyl; Rx and Ry are each independently hydrogen, (C1-C6)alkyl, (C3-C6)cycloalkyl, phenyl, benzyl, phenethyl, or (C1-C6)alkanoyl; or Rx and Ry together with the nitrogen to which they are attached are pyrrolidino, piperidino or morpholino;
     wherein any (C1-C6)alkyl of R1, R4-R7, Rw, Rx, and Ry is optionally substituted with one or more halo, hydroxy, (C1-C6)alkoxy, (C3-C6)cycloalkyloxy, (C1-C6)alkanoyl, (C1-C6)alkanoyloxy, trifluoromethyl, azido, cyano, oxo (=O), (C1-C6)alkyl, (C3-C6)cycloalkyl, (C3-C6)cycloalkyl(C1-C6)alkyl, (C1-C6)alkyl-S-(C1-C6)alkyl-, aryl, heteroaryl, alkyl(C1-C6)alkyl, or heteroaryl(C1-C6)alkyl, or NRajRak; wherein each Raj and Rak is independently hydrogen, (C1-C6)alkyl, (C3-C6)cycloalkyl, phenyl, benzyl, or phenethyl; and
     wherein any aryl or heteroaryl may optionally be substituted with one or more substituents selected from the group consisting of halo, hydroxy, (C1-C6)alkyl, (C3-C6)cycloalkyl, (C1-C6)alkoxy, (C3-C6)cycloalkyloxy, (C1-C6)alkanoyl, (C1-C6)alkanoyloxy, trifluoromethyl, trifluoromethoxy, nitro, cyano, and amino; or
     a pharmaceutically acceptable salt thereof.

Sofosbuvir falls within the claimed genus and is an FDA-approved drug marketed by Gilead for treating chronic hepatitis C infections. If the ’830 patent were found to be valid, it would be a barrier to the sale of sofosbuvir without authority. Gilead petitioned for IPR of claims 1-9, 11-21, and 23-28, arguing that these claims were not entitled to their claimed priority date and were therefore anticipated by U.S. 2010/0016251 to Sofia (“Sofia”), which was published on January 21, 2010. Sofia is a patent publication owned by Gilead and discloses every limitation of the challenged claim. The result of the IPR thus hinged on Sofia’s prior art status and the critical date of the ’830 patent. The application that issued as the ’830 patent claims priority from four applications filed on the following dates:

                        Description                                          Date

U.S. Provisional App. 60/634,677 ("P1")            Dec. 9, 2004
Int. App. PCT/US2005/044442 ("NP2")              Dec. 8, 2005
U.S. Patent App. 11/721,325 ("NP3")                 June 8, 2007
Sofia Publication                                                    Jan. 21, 2010
U.S. Patent App. 13/753,252 ("NP4")                 Jan. 29, 2013

The Board found that NP4 was filed after Sofia was published, and that NP3 contained the same disclosure as NP2. The Board focused its priority analysis on the disclosures of NP2 and P1, filed before Sofia was published. The Board held that NP2-P1 failed to provide written description sufficient to support the ’830 patent’s priority claim. According to the Board, these documents contained neither ipsis verbis support nor sufficient blaze marks to guide the skilled artisan to the claims of the ’830 patent. Thus, the challenged claims were not entitled to a priority date earlier than their own filing date of March 28, 2014, and, therefore, were anticipated by Sofia.

On appeal, Minnesota argued that the Board erred in holding that NP2-P1 did not show a written description of what was claimed in the ’830 patent. The Court disagreed. “Written description of an invention claimed as a genus of chemical compounds, as here, raises particular issues because, as we have held, 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. See Ariad Pharms., Inc. v. Eli Lilly & Co., 598 F.3d 1336, 1350−52 (Fed. Cir. 2010) (en banc). A broad outline of a genus’s perimeter is insufficient. See id.” The Court noted that Minnesota was not arguing in this case that it described a sufficient number of species to constitute a written description of the claimed subgenus. “Rather, Minnesota asserts that its earlier NP2-P1 applications literally described, or provided blaze marks to, the subgenus of the ’830 claims in its broad outlines. The Board held that they did not, and we agree.”

One issue considered by the Court on appeal was whether the Board’s finding that the later-filed ’830 patent was not entitled to the filing dates of the earlier filed NP2-P1 applications was supported by substantial evidence. The disclosure of NP2-P1, being broader than claim 1 of the ’830 patent, has a relationship of genus to the narrower subgenus of the ’830 patent claims. For genus claims, which were present here, the Court looked for blaze marks within the disclosure that guide attention to the claimed species or subgenus.

Minnesota asserted that P1 claim 47, combined with other claims of P1 reciting various substituents of the formula, provided an ipsis verbis disclosure of the subgenus claimed in the ’830 patent. Like the Board, the Court did not agree. “Following 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 noted that “all those optional choices do not define the intended result that is claim 1 of the ’830 patent.” According to the Court, this case was similar to Fujikawa v. Wattanasin, 93 F.3d 1559, 1571 (Fed. Cir. 1996), as “the claims of P1 recited a compendium of common organic chemical functional groups, yielding a laundry list disclosure of different moieties for every possible side chain or functional group. Indeed, the listings of possibilities are so long, and so interwoven, that it is quite unclear how many compounds actually fall within the described genera and subgenera.” The Court affirmed the Board’s decision that there was no ipsis verbis written description disclosure provided by P1 claim 47 sufficient to support the ’830 patent’s claims.

The Court further concluded that the Board’s finding that NP2-P1 failed to provide sufficient blaze marks to support the ’830 patent’s priority claims was supported by substantial evidence. The Board explained that an ipsis verbis disclosure of a claimed subgenus was not necessary to satisfy the written description requirement of § 112 and turned its attention to whether NP2-P1 provided sufficient blaze marks to provide written description support for the ’830 patent claims. As explained by the Board, “[t]hese blaze marks must be clear because ‘it is easy to bypass a tree in the forest, even one that lies close to the trail.’” The Board concluded that, “[i]n this case, we find the point at which one must leave the trail to find the tree is not well marked in P1 and NP2. Thus, P1 and NP2 do not provide sufficient written description support for the subgenus of challenged claim 1.” After failing to establish that P1 claim 47 constitutes an ipsis verbis disclosure, Minnesota attempted to recast this claim as a blaze mark. But the Court concluded that “again, similar to Fujikawa, even if P1 claim 47 ‘blaze[s] a trail through the forest’ that runs close by the later-claimed tree, the priority applications ‘do[] not direct one to the proposed tree in particular, and do[] not teach the point at which one should leave the trail to find it.’”

The Court further noted that Minnesota mischaracterized Ariad as holding that merely “disclosing ‘structural features common to the members of [a] genus’ demonstrates possession of, and thereby supports, the claimed genus.” “That is not what Ariad held”. “As the Board recognized, sufficiently describing a genus under Ariad requires a description of a claimed genus disclosing either (1) ‘a representative number of species falling within the scope of the genus,’ which the parties do not dispute is lacking here, or (2) ‘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 first requirement was not at issue here. As for the second, the Board addressed the question whether a skilled in the art would have been able to visualize or recognize the members of the claimed genus by “search[ing] for blaze marks that guided a skilled artisan to the claimed subgenera.” Regarding whether common structural features must exist between a claim and a putative priority disclosure, those features must constitute the near-entirety of the structures being compared. The Court agreed that the structures here were so extensive and varied that the structures of P1 claim 47, which, through its multiple dependencies, encompasses a significantly larger genus than that claimed in the ’830 patent, were not sufficiently common to that of claim 1 of the ’830 patent to provide written description support. “Finding no adequate blaze marks, the Board concluded that NP2-P1 do not provide sufficient written description to support the ’830 patent claims. Because NP3 provides the same disclosure as NP2, it too does not provide sufficient written description to support the ’830 patent claims. The Board thus determined that the claims of the ’830 patent were therefore entitled to a priority date no earlier than March 28, 2014, making Sofia prior art to them.” The Court noted that the parties did not dispute that Sofia disclosed each and every limitation of the ’830 patent claims. The Board found that the challenged claims of the ’830 patent were anticipated by Sofia. The Court affirmed.

Regents of the University of Minnesota v. Gilead Sciences, Inc., No. 21-2168 (Fed. Cir. March 6, 2023)