PTAB

IPR2013-00430

Apotex Corp v. Alcon Research Ltd

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Petition
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1. Case Identification

2. Patent Overview

  • Title: Self Preserved Aqueous Pharmaceutical Compositions
  • Brief Description: The ’941 patent discloses multi-dose, self-preserved ophthalmic compositions. The compositions contain a therapeutically effective agent and a specific preservative system comprising borate, a polyol (sorbitol and propylene glycol), and zinc ions intended to provide sufficient antimicrobial activity to meet USP preservative efficacy requirements.

3. Grounds for Unpatentability

Ground 1: Obviousness over Xia and Chowhan - Claims 1, 4, 7, and 9 are obvious over Xia in view of Chowhan.

  • Prior Art Relied Upon: Xia (International Publication No. WO 2005/097067) and Chowhan (Patent 6,143,799).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that the combination of Xia and Chowhan disclosed all elements of the claimed ophthalmic composition. Independent claim 1 recites a preservative system with specific concentration ranges for borate, polyol (sorbitol and propylene glycol), and zinc ions. Xia taught ophthalmic compositions using a soluble zinc compound to enhance preservative efficacy. Chowhan taught ophthalmic compositions using borate-polyol complexes as an antimicrobial system and identified sorbitol and propylene glycol as preferred polyols. Petitioner asserted that the concentration ranges disclosed in Xia and Chowhan for these components overlap with and render obvious the ranges recited in the challenged claims. Petitioner further argued that the limitation requiring the composition to satisfy USP 26 preservative requirements was an inherent property of the combined prior art teachings, as both references disclosed compositions that met similar or more stringent antimicrobial standards.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSA) would combine Xia and Chowhan to achieve an effective preservative system while minimizing the concentration of agents, thereby avoiding the known irritation and toxicity associated with traditional ophthalmic preservatives. Xia taught that zinc could enhance other agents, and Chowhan taught that borate-polyol systems could do the same. Combining the two known, low-irritation systems was a logical step to create a robust, self-preserved formulation.
    • Expectation of Success: A POSA would have a reasonable expectation of success because both references described stable and effective ophthalmic compositions. The components were known to be compatible, and optimizing their concentrations to achieve the desired preservative effect was considered routine experimentation. Petitioner argued that the claimed concentration ranges were merely the result of discovering an optimum within ranges already disclosed in the art.

Ground 2: Obviousness over Xia, Chowhan, and Travatan Label - Claims 2, 3, 5, 6, 8, and 10 are obvious over Xia, Chowhan, and the Travatan Label.

  • Prior Art Relied Upon: Xia (WO 2005/097067), Chowhan (Patent 6,143,799), and the FDA-approved drug label for Travatan® ("TL").

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground built upon the base composition established in Ground 1. The challenged dependent claims add limitations requiring the therapeutic agent to be a prostaglandin analog, specifically travoprost. Xia taught that its preservative system could be used with various therapeutic agents, including prostaglandins. The TL, a publicly available document for a commercial ophthalmic product, explicitly disclosed a formulation containing the specific prostaglandin analog travoprost. Petitioner contended that the TL supplied the missing element of the specific active agent recited in the dependent claims.
    • Motivation to Combine: A POSA, following Xia's teaching to formulate a composition with a prostaglandin, would naturally look to known, commercially successful prostaglandin products for a suitable agent. The TL provided a readily available example of such an agent (travoprost) used in an ophthalmic solution. Therefore, a POSA would combine the preservative system from Xia and Chowhan with the specific active agent taught by the TL.
    • Expectation of Success: Success was expected because the TL demonstrated that travoprost was safe and effective for topical ophthalmic use. Incorporating this known agent into the stable and effective preservative base taught by Xia and Chowhan would be a predictable and straightforward formulation task for a POSA.

  • Additional Grounds: Petitioner asserted additional obviousness challenges based on combinations including Kiyobayashi (Japanese Application # 2003-104870). Kiyobayashi was used to provide further teachings on ophthalmic compositions containing zinc, borate, and polyols, reinforcing the argument that using low concentrations of zinc as an antimicrobial agent was well-known in the art.

4. Key Claim Construction Positions

Petitioner proposed the broadest reasonable interpretation for several key claim terms, arguing these constructions were necessary to properly evaluate the prior art.

  • "zinc ions": Petitioner argued this term encompassed the concentration of the zinc salt (e.g., zinc chloride) added to the composition, assuming complete dissociation. This interpretation was critical for comparing the claimed concentration range to the zinc salt concentrations disclosed in the prior art.
  • "polyol": This term was construed as "any compound having at least one hydroxyl group on each of two adjacent carbon atoms that are not in trans configuration relative to each other," consistent with the patent’s specification.
  • "self-preserved": Petitioner argued a POSA would understand this term to mean a composition not susceptible to significant microbial growth due to its inherent antimicrobial properties, allowing it to be used in a multi-dose container.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-10 of the ’941 patent as unpatentable under 35 U.S.C. §103.