The US Court of Appeals for the Federal Circuit reversed a Patent Trial and Appeal Board (PTAB) obviousness decision, finding the decision was infected by an erroneous claim construction that failed to consider the purpose of the claimed invention. Kaken Pharmaceutical Co., LTD v. Iancu, Case No. 18-2232 (Fed. Cir. Mar. 13 2020)(Taranto, J.).

Kaken owns a patent claiming a method for topically treating fungal infections in nails. Fungal infections of the nail plate and nail bed are notoriously difficult to treat because topical treatments cannot penetrate the thick keratin in the nail plate. The patent describes an effective topical treatment with an antifungal, KP-103, having good permeability, retention capacity and activity in the nail plate. The patent specification notes that topical treatments known in the prior art were largely ineffective at penetrating the nail plate and treating onychomycosis.

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