Associated British Foods v. Cornell Research Foundation Inc

1. Case Identification

• Case #: IPR2019-00580
• Patent #: 7,312,063
• 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: 1-3 and 5-8

2. Patent Overview

• Title: Overexpression of Phytase Genes in Yeast Systems
• Brief Description: The ’063 patent discloses methods for producing the enzyme phytase, which is used as an animal feed additive. The method involves expressing a heterologous polynucleotide from a non-yeast organism, specifically Escherichia coli (E. coli), in a yeast host cell and then isolating the resulting protein, which is claimed to have increased thermostability compared to the same protein expressed in a non-yeast host.

3. Grounds for Unpatentability

Ground 1: Anticipation Under 35 U.S.C. § 102(e) - Claims 1-3, 5, 7, and 8 are anticipated by Kretz.

• Prior Art Relied Upon: Kretz (Patent 5,876,997).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Kretz teaches every element of the claimed method. Kretz discloses a polynucleotide encoding an E. coli phytase, teaches expressing this gene in recombinant host cells including yeast, and discloses methods for isolating the expressed protein. For dependent claims 2 and 3, which specify Pichia yeast, Petitioner contended that Kretz's disclosure of the genus "yeast" anticipates the species Pichia because, at the time of the invention, Pichia was one of a small, well-defined, and commonly used class of yeasts for such purposes, which a POSITA would have immediately envisaged.
  • Key Aspects: The central argument for this ground rested on inherency. Petitioner asserted that the claimed "increased thermostability" is a necessary and inherent result of expressing an E. coli phytase in a yeast host. This increased stability is due to glycosylation, a post-translational modification that occurs in yeast but not in bacterial hosts like E. coli. Therefore, practicing the method disclosed by Kretz would inherently produce a phytase with the claimed thermostability.

Ground 2: Obviousness Under 35 U.S.C. § 103(a) - Claims 1-3 and 5-8 are obvious over Kretz, Cheng, and Olsen.

• Prior Art Relied Upon: Kretz (Patent 5,876,997), Cheng (Patent 5,985,605), and Olsen (a 1991 article in J. Gen. Microbiology).
• Core Argument for this Ground:
  • Prior Art Mapping: Kretz provided the foundational teaching of expressing an E. coli phytase in yeast. While Kretz did not specify a particular yeast species, Cheng taught specific methods for producing high yields of bacterial phytases in well-characterized industrial yeasts, including Pichia. Olsen taught that expressing bacterial enzymes in yeast results in glycosylation, which confers substantially higher thermostability compared to expression in the native bacterial host.
  • Motivation to Combine: A POSITA would combine Kretz’s disclosure of a useful E. coli phytase with Cheng’s methods for efficient, high-yield production in a specific yeast host like Pichia to improve production volume and reduce costs. Olsen provided the explicit motivation to use a yeast host to achieve the desired property of increased thermostability, teaching that this was a known benefit of yeast expression systems.
  • Expectation of Success: Petitioner argued a POSITA would have a high expectation of success because Kretz and Cheng both involved expressing phytases in yeast, and Olsen explained the scientific basis (glycosylation) for the expected increase in thermostability.

Ground 4: Obviousness Under 35 U.S.C. § 103(a) - Claims 1-3 and 5-8 are obvious over Greiner, Dassa, Romanos, Van Gorcom, and Olsen.

• Prior Art Relied Upon: Greiner (a 1993 article in Archives of Biochemistry & Biophysics), Dassa (a 1990 article in J. Bacteriology), Romanos (a 1995 article in Current Opinion in Biotechnology), Van Gorcom (Patent 5,436,156), and Olsen (a 1991 article in J. Gen. Microbiology).

• Core Argument for this Ground:

  • Prior Art Mapping: This ground established the obviousness of the claimed invention starting from a different set of primary references. Dassa disclosed the gene sequence for E. coli AppA phytase, and Greiner confirmed its high phytase activity and inherent stability. Romanos taught that Pichia was a "mainstream expression host" known to produce "extremely high yields" of proteins. Van Gorcom taught industrially-viable methods for expressing phytases in various fungal cells, including yeast, and noted the high degree of homology among microbial phytase genes.
  • Motivation to Combine: A POSITA, knowing of the beneficial E. coli phytase from Greiner and Dassa, would combine it with the efficient, high-yield yeast expression systems taught by Romanos and Van Gorcom to produce the enzyme economically. Romanos's teaching of Pichia as a superior host would have directly motivated its selection. Olsen again supplied the reason to expect increased thermostability from this combination.
  • Expectation of Success: Success was expected because Romanos and Van Gorcom provided detailed methods for expressing heterologous proteins in yeast, and Van Gorcom explicitly noted the homology across phytase genes, suggesting that techniques for one would likely work for another, such as the E. coli phytase from Dassa and Greiner.

• Additional Grounds: Petitioner also asserted Ground III, alleging claims 1-3 and 5-8 are obvious over Greiner, Dassa, Cheng, and Olsen. This ground used a similar logic to Ground IV but relied on Cheng instead of Romanos and Van Gorcom to teach the high-yield yeast expression system.

4. Key Claim Construction Positions

• Petitioner argued that the term "a phytase from Escherichia coli" should be construed as "a phytase isolated from wild type Escherichia coli." This construction was presented as narrower than the Patent Owner's proposed construction ("Any phytase derived from Escherichia coli"). Petitioner contended that the prior art meets even this narrower construction, and therefore the claims are unpatentable under any plausible interpretation.

5. Arguments Regarding Discretionary Denial

• Petitioner argued that the grounds presented were not cumulative of issues previously considered by the USPTO, making discretionary denial under §325(d) inappropriate. Petitioner asserted that the examiner never considered the specific prior art combinations presented in the petition. For instance, the record did not show that the examiner considered Greiner’s disclosure of phytase activity for the Dassa enzyme. Crucially, Petitioner argued that the examiner was not presented with Olsen, which teaches that increased thermostability is an expected outcome of expressing a bacterial enzyme in yeast, directly contradicting the patentee’s arguments of unexpected results during prosecution.

6. Relief Requested

• Petitioner requested the institution of an inter partes review and the cancellation of claims 1-3 and 5-8 of Patent 7,312,063 as unpatentable.