PTAB

IPR2018-00171

FlatWing Pharmaceuticals, LLC v. Anacor Pharmaceuticals, Inc.

1. Case Identification

2. Patent Overview

  • Title: BORON-CONTAINING SMALL MOLECULES
  • Brief Description: The ’823 patent relates to a method for treating onychomycosis (fungal nail infection) in humans. The method involves topically applying a pharmaceutical composition containing the boron-based compound tavaborole (1,3-dihydro-5-fluoro-1-hydroxy-2,1-benzoxaborole) to treat infections caused by the dermatophytes Trichophyton rubrum or Trichophyton mentagrophytes.

3. Grounds for Unpatentability

Ground 1: Obviousness over Austin and Brehove - Claims 1 and 4-6 are obvious over Austin in view of Brehove.

  • Prior Art Relied Upon: Austin (WO 1995/033754) and Brehove (Application # 2002/0165121).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Austin disclosed the exact compound claimed in the ’823 patent, tavaborole, and established its high potency as a fungicide against Candida albicans, a known cause of onychomycosis. Brehove taught a method of treating onychomycosis in humans caused by the specifically claimed pathogens (T. rubrum and T. mentagrophytes) by topically applying different, but related, boron-containing compounds. Brehove further disclosed a once-daily application regimen, directly mapping to the limitation of dependent claim 4.
    • Motivation to Combine: A person of ordinary skill in the art (POSITA) would combine these teachings by substituting Austin’s known, potent tavaborole for the active ingredient in Brehove’s established topical treatment method. The primary motivation was the simple substitution of one known fungicide for another to improve efficacy. Petitioner argued tavaborole’s lower molecular weight compared to the compounds in Brehove would have been a strong driver, as lower weight was known to improve nail penetration.
    • Expectation of Success: A POSITA would have a reasonable expectation of success for several reasons. Both references operate in the same field of boron-based antifungals, and their compounds share structural similarities. Furthermore, Brehove provided direct evidence that an industrial biocide (BioborJF®) could be safely and effectively formulated for human topical use, directly refuting the patent owner’s prosecution argument that a POSITA would be deterred from using an "industrial" fungicide like tavaborole from Austin.

Ground 2: Obviousness over Austin and Freeman - Claims 1 and 4-6 are obvious over Austin in view of Freeman.

  • Prior Art Relied Upon: Austin (WO 1995/033754) and Freeman (WO 2003/009689).

  • Core Argument for this Ground:

    • Prior Art Mapping: The argument paralleled Ground 1. Austin again supplied the claimed compound, tavaborole, and its antifungal properties. Freeman disclosed methods of treating onychomycosis by topically applying other boron-based compounds (phenyl boronic acid derivatives) and specifically identified T. rubrum and Candida species as target pathogens. Freeman also taught a once-daily application regimen, mapping to dependent claim 4.
    • Motivation to Combine: A POSITA would be motivated to substitute the tavaborole from Austin into the topical antifungal compositions disclosed by Freeman. This was presented as a straightforward substitution of one structurally similar, boron-based antifungal for another in a known application to achieve a predictable result. Tavaborole’s high potency, as shown in Austin, provided a clear reason for its selection.
    • Expectation of Success: Success was expected because tavaborole is structurally similar to the phenyl boronic acid (PBA) derivatives in Freeman, and both exhibit fungicidal activity against pathogens causing onychomycosis. The similar molecular weight of tavaborole to Freeman's compounds would suggest comparable nail penetration and efficacy, giving a POSITA a strong basis to expect the combination would work as intended.
  • Additional Grounds: Petitioner asserted additional obviousness challenges against dependent claims 2 and 3 based on combinations including Samour (Patent 6,224,887). These grounds argued that Samour, which taught durable nail lacquer formulations for onychomycosis, supplied the remaining limitations of claims 2 and 3, including a 5% w/w concentration of the active ingredient and the use of ethanol and propylene glycol as excipients. A POSITA would have been motivated to incorporate the active ingredient from Austin/Brehove or Austin/Freeman into Samour's improved lacquer vehicle to enhance drug delivery and stability.

4. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-6 of Patent 9,572,823 as unpatentable under 35 U.S.C. § 102 and/or § 103.