Mylan Pharmaceuticals Inc v. Pfizer Inc

1. Case Identification

• Case #: IPR2018-01360
• Patent #: 9,566,290
• Filed: July 10, 2018
• Petitioner(s): Mylan Pharmaceuticals Inc.
• Patent Owner(s): Anacor Pharmaceuticals, Inc.
• Challenged Claims: 1-12

2. Patent Overview

• Title: Boron-Containing Small Molecules
• Brief Description: The ’290 patent discloses methods for treating onychomycosis (nail fungus) by topically administering a pharmaceutical composition containing tavaborole, a boron-based compound, to the nail of a human.

3. Grounds for Unpatentability

Ground 1: Claims 1, 4, 7, 9-10 are obvious over Austin in view of Brehove

• Prior Art Relied Upon: Austin (International Publication No. 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 ’290 patent (tavaborole, an oxaborole) and taught it was a "particularly effective" fungicide with high potency against Candida albicans, a known cause of onychomycosis. Brehove taught topically applying different boron-containing compounds (dioxaborinanes) to human nails to successfully treat onychomycosis caused by Trichophyton rubrum and Trichophyton mentagrophytes, the same pathogens recited in the challenged claims. Petitioner asserted that combining Austin's preferred compound with Brehove's method of treatment renders the claims obvious. The limitation requiring inhibition of an aminoacyl tRNA synthetase was argued to be an inherent property of tavaborole's known mechanism of action, not a patentable distinction.
  • Motivation to Combine: A person of ordinary skill in the art (POSITA) would combine these references because both taught using boron-containing compounds as effective fungicides for treating onychomycosis. A POSITA would have been motivated to substitute Austin's tavaborole for the active ingredients in Brehove's method for three primary reasons: (1) both references taught efficacy against onychomycosis-causing yeasts, suggesting interchangeable use; (2) tavaborole's significantly lower molecular weight (151.93 Daltons) compared to Brehove's compounds (>269 Daltons) would be expected to improve nail penetration and efficacy; and (3) Brehove demonstrated that an industrial biocide could be safely and effectively repurposed for human topical treatment, overcoming any potential hesitation about using Austin's compound.
  • Expectation of Success: A POSITA would have a reasonable expectation of success because the compounds in Austin and Brehove shared structural features (boron heterocycles) and similar fungicidal activity against Candida albicans. This known activity was argued to be predictive of efficacy against the claimed dermatophytes. The known benefits of lower molecular weight for nail penetration, coupled with Brehove's successful clinical application, would further support a high likelihood of success.

Ground 2: Claims 2-3, 5-6, 8, 11-12 are obvious over Austin in view of Brehove and Samour

• Prior Art Relied Upon: Austin (International Publication No. WO 1995/033754), Brehove (Application # 2002/0165121), and Samour (Patent 6,224,887).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground built upon the combination of Austin and Brehove to address dependent claims reciting specific formulation details. Petitioner contended that Samour taught topical nail lacquer compositions for treating onychomycosis that disclosed the remaining claim limitations. Specifically, Samour taught formulations with a 5% concentration of an active antifungal agent (meeting claims 2 and 5), and the use of ethanol and propylene glycol as carriers or plasticizers (meeting claims 3 and 6). Samour also taught once-a-day administration, corresponding to the limitation in claim 8.
  • Motivation to Combine: A POSITA, having decided to use tavaborole in a topical treatment as suggested by Austin and Brehove, would have been motivated to consult a reference like Samour to optimize the delivery vehicle. Samour explicitly taught improved nail lacquer formulations with enhanced durability, water resistance, and diffusion characteristics. A POSITA would combine Samour's improved lacquer base with Austin's superior active ingredient (tavaborole) to create a more effective and user-friendly product.
  • Expectation of Success: Success was reasonably expected because formulating topical drugs was a well-known art involving routine experimentation. Samour provided explicit examples of stable, effective 5% antifungal lacquers containing the same excipients claimed in the ’290 patent. Therefore, a POSITA would expect that substituting tavaborole for the active ingredient in Samour's formulation—especially given tavaborole's lower molecular weight compared to Samour's preferred antifungal—would result in an effective treatment for onychomycosis.

Ground 3: Claims 1, 4, 7, 9-10 are obvious over Austin in view of Freeman

• Prior Art Relied Upon: Austin (International Publication No. WO 1995/033754) and Freeman (International Publication No. WO 2003/009689).

• Core Argument for this Ground:

  • Prior Art Mapping: This ground presented a parallel argument to Ground 1, substituting Freeman for Brehove. Petitioner asserted that Freeman, like Brehove, taught a method of treating onychomycosis in humans by topically applying boron-containing compounds (phenyl boronic acids). Freeman explicitly disclosed treating infections caused by T. rubrum and Candida species and taught once-daily application until cure. The combination of Austin’s superior compound (tavaborole) with Freeman’s established method of use for a similar class of compounds was argued to render the independent claims obvious.
  • Motivation to Combine: The motivation to combine Austin and Freeman was similar to that for combining Austin and Brehove. Both references were directed to using boron compounds as topical antifungals. A POSITA would be motivated to replace the active ingredients in Freeman with tavaborole from Austin due to the structural similarities between the compounds and tavaborole's demonstrated high potency. Furthermore, tavaborole has a molecular weight similar to the compounds in Freeman, suggesting it would be an effective substitute for penetrating the nail plate.
  • Expectation of Success: A POSITA would have a reasonable expectation of success due to the structural and functional similarities between the compounds in Austin and Freeman. Both were shown to be effective against fungi that cause onychomycosis. Since Freeman already established a method for the topical use of boron compounds to treat the claimed pathogens, a POSITA would reasonably expect that substituting a more potent, structurally similar boron compound from Austin into that method would be successful.

• Additional Grounds: Petitioner asserted an additional obviousness challenge for claims 2-3, 5-6, 8, and 11-12 based on the combination of Austin, Freeman, and Samour, which paralleled the reasoning in Ground 2.

4. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claims 1-12 of the ’290 patent as unpatentable under 35 U.S.C. §103.