Efinaconazole – USA

On Mar. 13, 2020, Federal Circuit reversed PTAB’s claim construction & thus vacated final written decision and remanded matter back to the PTAB.

Acrux filed inter partes review (IPR) of all claims (1-2) of U.S. Patent No. 7,214,506. US’506 patent claims methods for topically treating fungal infections in human nails. Board issued claim construction & ultimately determined that all claims of the ’506 patent are unpatentable for obviousness. During IPR, Kaken proposed that the phrase “treating a subject having onychomycosis” means “treating the infection at least where it primarily resides in the keratinized nail plate and underlying nail bed.”  Board rejected Kaken’s construction as too narrow, concluding that “the express definition of onychomycosis includes superficial mycosis, which in turn is expressly defined as a disease that lies in the skin or visible mucosa.” Accordingly, the Board concluded, “treating onychomycosis” includes treating “superficial mycosis that involves disease of the skin or visible mucosa.” Applying that construction, the Board determined that a skilled artisan would have been motivated to combine the cited references and thus the claims are obvious.

During appeal, Kaken challenges the Board’s construction of “treating a subject having onychomycosis.” According to Kaken, the Board’s construction ignores the ’506 patent’s core innovation—“a topical treatment that can easily penetrate the tough keratin in the nail plate”. Federal Circuit said that the Board drew an unwarranted inference from the broad definition in specification. As a matter of ordinary meaning, a statement that a particular disease invades the body would not imply that it can invade any part of the body. So too, when the specification says that “onychomycosis” is a disease involving invasion of the “nail,” it does not compel the conclusion that the disease can invade any part of the defined “nail.”

Moreover, other parts of the specification, which explain that an effective topical treatment would need to penetrate the nail plate, support Kaken’s construction. The ’506 patent briefly describes topical treatments known in the prior art. It notes that those treatments were largely ineffective because they “could not sufficiently permeate the thick keratin in the nail plate.” Accordingly, the ’506 patent explains, an effective topical treatment must have “good permeability, good retention capacity and conservation of high activity in the nail plate.” Also, the prosecution history—which includes, specifically, statements made by Kaken to overcome a rejection and the examiner’s statements explaining withdrawal of the rejection based on those statements—provides decisive support for limiting the claim phrase at issue to a plate-penetrating treatment of an infection inside or under the nail plate. The Board relied on its erroneous claim construction throughout its consideration of facts that were part of its obviousness analysis. Thus, federal Circuit vacated the Board’s decision & remanded matter back to the board for reconsideration.