Rejecting a patent owner's arguments relating to due process and structural and functional similarities regarding obviousness, the US Court of Appeals for the Federal Circuit affirmed a Patent Trial and Appeal Board (PTAB) obviousness finding. Anacor Pharmaceuticals, Inc. v. Iancu, Case No. 17-1947 (Fed. Cir., May 14, 2018) (Bryson, J).

Anacor owns a patent directed to the use of tavaborole (a specific boron heterocycle) to treat fungal infections, including onychomycosis such as tinea unguium. Tinea unguium is caused by dermatophytes, and onychomycosis can also be caused by C. albicans. During an inter partes review (IPR) proceeding, the PTAB found all claims of Anacor's patent obvious over the combination of two references. According to the PTAB, one of the two references taught that tavaborole is most effective against C. albicans among a table of compounds tested, and that tavaborole has a relatively low molecular weight. The PTAB found that molecular weight was the most important factor in predicting whether a molecule would penetrate the nail plate. The PTAB further found that the other reference taught the treatment of onychomycosis with boron heterocycles in a topical composition, where the boron heterocycles were effective against C. albicans

Acknowledging that the boron heterocycles disclosed in the two references were structurally different, and recognizing that small structural differences can cause different properties, the PTAB nevertheless concluded that a skilled artisan would have been motivated to combine the two references. Using evidence in addition to the two references, the PTAB concluded one of ordinary skill would have had a reasonable expectation that a compound with activity against C. albicans would also have activity against dermatophytes. Anacor appealed.

Anacor argued that the PTAB adopted a new theory of obviousness without giving Anacor proper notice or an opportunity to respond. The Federal Circuit disagreed, finding that the PTAB's final decision was based on the same combination of references and the same inferences drawn by the IPR petition.

Anacor also argued that the PTAB's decision improperly relied on additional references not cited in the petition. The Court rejected this argument, finding that there is no blanket prohibition on introducing new evidence in an IPR as long as the other party is given proper notice and an opportunity to respond, and that introduction of new evidence after petition is expected for replying to evidence introduced by the patent owner. The Court found that alleged additional references were discussed by Anacor in its patent owner's response and in Anacor's expert declaration.

Turning to the obviousness finding, the Federal Circuit found that Anacor inaccurately characterized the PTAB's assessment of structural similarity. While some structural similarities between the two references may be evidence of good candidates to be combined, the Court found that the PTAB appropriately attributed more significance to the functional similarities of the two groups of compounds. The Court concluded that the combination of structural and functional similarities in the references supported the PTAB's obviousness analysis, and therefore affirmed the PTAB's decision.

Obviousness Finding Properly Based On Combination Of Structural And Functional Similarities

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