PTAB

IPR2019-00577

Associated British Foods v. Cornell Research Foundation Inc

Log In
Key Events
Petition

1. Case Identification

2. Patent Overview

  • Title: Overexpression of Phytase Genes in Yeast Systems
  • Brief Description: The ’300 patent describes methods for producing the enzyme Escherichia coli (E. coli) phytase, which is used as an animal feed additive. The claimed methods involve providing a polynucleotide that encodes the bacterial phytase, expressing that polynucleotide in fungal host cells, and subsequently isolating the expressed enzyme.

3. Grounds for Unpatentability

Ground I: Claims 1, 3-8, 10-13, 15-19, and 21-23 are anticipated by Kretz under 35 U.S.C. §102(e).

  • Prior Art Relied Upon: Kretz (Patent 5,876,997).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Kretz disclosed every element of the challenged claims. Kretz taught a method of producing E. coli phytase by providing its complete polynucleotide sequence, expressing it in recombinant host cells including fungal cells such as yeast, and isolating the resulting enzyme. Petitioner asserted that Kretz also disclosed the inherent thermostability of E. coli phytase, thereby anticipating dependent claims reciting specific temperature stability profiles (claims 10-12, 21-23), as these properties are a natural result of practicing the disclosed method.

Ground II: Claims 1-23 are obvious over Kretz in view of Cheng under 35 U.S.C. §103.

  • Prior Art Relied Upon: Kretz (Patent 5,876,997), Cheng (Patent 5,985,605).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner contended that Kretz taught the core invention: providing a polynucleotide for E. coli phytase and expressing it in fungal cells. Cheng was argued to supply specific, well-characterized, and industrially recognized methods for expressing bacterial phytases in high-yield fungal hosts, such as Pichia and Aspergillus, to increase efficiency.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSA) would combine the desirable, thermostable E. coli phytase from Kretz with the efficient, high-yield production methods and host cells taught by Cheng. The motivation was economic: to increase the volume and efficiency of enzyme production while reducing costs for commercial use as an animal feed additive.
    • Expectation of Success: A POSA would have a reasonable expectation of success because Kretz already suggested expressing its phytase in fungal cells generally. Cheng provided established, detailed protocols for expressing similar bacterial enzymes in specific, industrially-proven fungal hosts, making the combination a straightforward application of known techniques.

Ground III: Claims 1-23 are obvious over Greiner, Dassa, and Cheng under §103.

  • Prior Art Relied Upon: Greiner (a 1993 article in Archives of Biochemistry & Biophysics), Dassa (a 1990 article in Journal of Bacteriology), and Cheng (Patent 5,985,605).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner argued that Dassa disclosed the complete polynucleotide sequence for E. coli AppA phytase, and Greiner confirmed that the resulting enzyme has phytase activity and possesses advantageous properties, such as stability at high temperatures. As in Ground II, Cheng provided the established methods for efficiently expressing such bacterial enzymes in high-yield fungal hosts like Pichia.
    • Motivation to Combine: A POSA would be motivated to produce the specific, well-characterized, and beneficial E. coli AppA phytase described by Greiner and Dassa. To do so economically, a POSA would have turned to the efficient, industrial-scale production systems for bacterial phytases taught by Cheng.
    • Expectation of Success: Success was reasonably expected because Cheng’s methods were known to be effective for various bacterial phytases. Applying these established methods to another known bacterial phytase (E. coli AppA from Dassa/Greiner) was presented as a predictable and logical step.

  • Additional Grounds: Petitioner asserted additional obviousness challenges, including that claims 1-23 are obvious over Greiner, Dassa, Romanos, and Van Gorcom, which relied on Romanos and Van Gorcom to teach the use of high-yield fungal hosts like Pichia and Aspergillus. Further grounds (V-VII) argued that the addition of Olsen (a 1991 article) to the combinations in Grounds II-IV would have explicitly taught and motivated a POSA to express the bacterial phytase in fungal cells to achieve the increased thermostability recited in claims 10-12 and 21-23.

4. Key Claim Construction Positions

  • "Escherichia coli phytase" / "E. coli AppA phytase": Petitioner argued these terms should be construed narrowly to mean "a phytase isolated from wild type Escherichia coli." Petitioner contended this construction was supported by the patent’s specification, which describes the genes as being "isolated from a bacterial cell."
  • "purified from the growth medium": Petitioner proposed this term be construed as "removed from the growth medium at a ratio of at least 80% pure." This construction was based on the specification’s preference for purity of "at least about 80%." Petitioner argued the prior art met the claims even under these narrower constructions.

5. Arguments Regarding Discretionary Denial

  • Petitioner argued that institution should not be denied under §325(d) because the grounds presented were not cumulative of issues previously considered by the USPTO. While some of the cited references were before the examiner during prosecution of related applications, they were never applied in the combinations asserted in the petition to reject the claims that issued in the ’300 patent. Petitioner contended that the examiner never evaluated the specific invalidity theories presented, such as the direct combination of Kretz and Cheng.

6. Relief Requested

  • Petitioner requests institution of an inter partes review (IPR) and cancellation of claims 1-23 of the ’300 patent as unpatentable.