Associated British Foods v. Cornell Research Foundation Inc

1. Case Identification

• Case #: IPR2019-00578
• Patent #: 8,455,232
• Filed: January 23, 2019
• Petitioner(s): Associated British Foods PLC, AB Vista, Inc., PGP International, Inc., ABITEC Corporation, AB Enzymes, Inc., and AB Enzymes GmbH
• Patent Owner(s): Cornell Research Foundation, Inc.
• Challenged Claims: 1-4

2. Patent Overview

• Title: Overexpression of Phytase Genes in Yeast Systems
• Brief Description: The ’232 patent describes methods of producing the enzyme phytase, which is used as an animal feed additive. The claimed method involves providing a polynucleotide that encodes a phytase from the bacterium Escherichia coli (E. coli), expressing that polynucleotide in a yeast host cell, and isolating the resulting protein.

3. Grounds for Unpatentability

Ground 1: Anticipation of Claims 1, 3, and 4 under 35 U.S.C. §102(e) over Kretz

• Prior Art Relied Upon: Kretz (Patent 5,876,997).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Kretz discloses every element of the claimed method. Kretz teaches a method of producing E. coli phytase by providing a polynucleotide isolated from E. coli B, expressing it in a recombinant host cell, and isolating the expressed protein. Kretz explicitly identifies "fungal cells, such as yeast" as appropriate host cells. For claim 3, which specifies the yeast Pichia, Petitioner contended that at the time of the invention, Pichia was one of a small, well-defined class of yeasts used for expressing phytases. Therefore, a person of ordinary skill in the art (POSA) would have immediately envisaged using Pichia from Kretz’s disclosure of "yeast." For claim 4, Kretz expressly teaches incorporating the polynucleotide into a vector for expression.
  • Key Aspects: The core of this ground rested on the argument that Kretz’s disclosure of "yeast" as a host was sufficiently specific to anticipate the species Pichia given the limited number of commonly used industrial yeasts for this purpose.

Ground 2: Obviousness of Claims 1-4 under 35 U.S.C. §103 over Kretz in view of Cheng

• Prior Art Relied Upon: Kretz (Patent 5,876,997) and Cheng (Patent 5,985,605).
• Core Argument for this Ground:
  • Prior Art Mapping: Kretz taught the general method of expressing a desirable, thermostable E. coli phytase in yeast hosts. However, Kretz did not identify specific yeast species. Cheng taught detailed methods for producing other bacterial phytases in industrially recognized yeast hosts, including Pichia and Saccharomyces, and disclosed that such methods lead to high yields and increased efficiency.
  • Motivation to Combine: A POSA would combine these references to implement the superior E. coli phytase from Kretz using the specific, high-yield production methods and yeast hosts (Pichia) taught by Cheng. The motivation was to increase the volume and efficiency of enzyme production and reduce costs, which were known benefits of using Cheng's methods.
  • Expectation of Success: A POSA would have a reasonable expectation of success because Kretz established that E. coli phytase could be expressed in yeast, and Cheng demonstrated that other bacterial phytases could be successfully expressed in Pichia with high yields.

Ground 3: Obviousness of Claims 1-4 under §103 over Greiner, Dassa, and Cheng

• Prior Art Relied Upon: Greiner (a 1993 journal article), Dassa (a 1990 journal article), and Cheng (Patent 5,985,605).
• Core Argument for this Ground:
  • Prior Art Mapping: Dassa disclosed the complete polynucleotide sequence for the E. coli appA gene. Greiner confirmed that the enzyme produced by this gene was, in fact, an E. coli AppA phytase with highly desirable properties, including stability at high temperatures and across a wide pH range. This combination provided the specific phytase of claim 2. Cheng, as in Ground 2, taught the efficient, industrial-scale methods for expressing bacterial phytases in yeast hosts like Pichia.
  • Motivation to Combine: A POSA would be motivated to produce the specific, advantageous E. coli AppA phytase identified by Greiner and Dassa using the efficient and economically viable yeast expression system disclosed by Cheng. This would address known issues with other phytases (e.g., inactivity of Aspergillus phytase at certain pH levels).
  • Expectation of Success: Success was reasonably expected because Cheng taught methods for expressing various bacterial phytases in industrially-recognized yeast hosts, making it predictable that the E. coli phytase from Greiner/Dassa could also be produced using these established techniques.

Ground 4: Obviousness of Claims 1-4 under §103 over Greiner, Dassa, Romanos, and Van Gorcom

• Prior Art Relied Upon: Greiner (1993 article), Dassa (1990 article), Romanos (1995 article), and Van Gorcom (Patent 5,436,156).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground presented an alternative combination for production methods. Greiner and Dassa again provided the target E. coli AppA phytase and its gene. Romanos identified Pichia as a "mainstream expression host" known to produce "extremely high yields" of proteins, making it a superior choice to other yeasts like Saccharomyces. Van Gorcom taught general, industrially-viable methods of expressing phytase genes from various microbes in fungal cells, including yeast, and taught the use of vectors.
  • Motivation to Combine: A POSA would be motivated to combine the superior phytase from Greiner/Dassa with the high-yield Pichia host system praised by Romanos, using the established industrial production methods taught by Van Gorcom. The goal was to achieve efficient, high-yield production of a better-performing phytase.
  • Expectation of Success: A POSA would have a reasonable expectation of success based on Van Gorcom's teaching that phytase genes share a high degree of homology across species and Romanos's teaching that Pichia is a suitable host for expressing bacterial enzymes.

4. Key Claim Construction Positions

• Petitioner asserted that the claim terms "a phytase from Escherichia coli" and "Escherichia coli AppA phytase" should be construed narrowly to mean a phytase isolated from wild type Escherichia coli. This is in contrast to the Patent Owner's proposed broader construction of any phytase "derived from" E. coli. Petitioner argued its narrower construction was supported by the patent's specification and still rendered the claims unpatentable, which would necessarily prove unpatentability under the broader construction as well.

5. Arguments Regarding Discretionary Denial

• Petitioner argued that the grounds presented in the petition were not cumulative of issues previously considered by the USPTO during prosecution of the ’232 patent or related applications. Petitioner contended that the Examiner never applied key prior art references like Kretz or Cheng to the claims. Furthermore, Petitioner argued that the specific combinations and invalidity theories—such as combining Kretz and Cheng to arrive at the claimed invention—were not previously evaluated by the Office.

6. Relief Requested

• Petitioner requested institution of an inter partes review and cancellation of claims 1-4 of the ’232 patent as unpatentable.