PTAB

IPR2021-00528

Pfizer Inc v. Amgen Inc

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Key Events
Petition

1. Case Identification

2. Patent Overview

  • Title: PROCESS FOR PURIFYING PROTEINS
  • Brief Description: The ’707 patent claims methods for purifying proteins using hydrophobic interaction chromatography (HIC). The process involves using a specific two-salt combination to increase the dynamic binding capacity (DBC) of the HIC column compared to using a single salt alone.

3. Grounds for Unpatentability

Ground I: Anticipation - Claims 1, 2, 4, 8, 10, and 11 are anticipated by Builder.

  • Prior Art Relied Upon: Builder (Patent 5,446,024).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Builder discloses a process for purifying a protein (IGF-I) using HIC that meets every limitation of the challenged claims. Builder expressly teaches "maximizing capacity" and discloses mixing a protein with a combination of ammonium sulfate and ammonium citrate (a claimed sulfate/citrate combination) at concentrations between 0.1M and 1M. Petitioner asserted that the claimed benefit of "increased dynamic capacity" is an inherent result of Builder's disclosed process, pointing to the ’707 patent’s own specification and a subsequent publication by its inventors stating the effect is a "universal phenomenon" for such dual-salt systems. Builder also discloses a pH range of "about 6-8," which overlaps the claimed range of pH 5-7, and teaches formulating the purified protein for pharmaceutical use.

Ground III: Obviousness over Builder and El Rassi - Claims 1, 2, 4, 8, 10, and 11 are obvious over Builder in view of El Rassi 1990 and a POSA's general knowledge.

  • Prior Art Relied Upon: Builder (Patent 5,446,024), El Rassi 1990 (a 1990 journal article on HIC salt gradients).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that to the extent Builder's disclosure of "maximizing capacity" is not an express teaching of "increasing dynamic capacity," this limitation would have been obvious. El Rassi 1990 teaches that using a dual-salt combination of sulfate and citrate—the same combination used in Builder—results in increased protein retention on an HIC column compared to using a single salt at a higher concentration.
    • Motivation to Combine: A POSA would have looked to references like El Rassi 1990 to understand the effects of the salt combinations taught in Builder. The well-understood correlation between increased protein retention and increased DBC would have motivated a POSA to apply El Rassi's findings to Builder's process to achieve the predictable result of increased column capacity.
    • Expectation of Success: A POSA would have reasonably expected that implementing the dual sulfate/citrate salt system taught by Builder, which El Rassi showed increases protein retention, would result in an increased DBC for the HIC column, as increased retention was known to correlate directly with increased binding capacity.

Ground IV: Obviousness over El Rassi and Pharmacia - Claims 1, 2, 4, 8, 10, and 11 are obvious over El Rassi 1990 in view of Pharmacia and a POSA's general knowledge.

  • Prior Art Relied Upon: El Rassi 1990, Pharmacia (a 1993 HIC handbook).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner asserted that El Rassi 1990 discloses using a claimed two-salt combination (ammonium sulfate and sodium citrate) within the claimed concentration range, which demonstrably increased protein retention. El Rassi's experiments were performed at pH 6.5, squarely within the claimed pH range. However, El Rassi describes a lab-scale process where the protein is dissolved in water before loading onto a pre-equilibrated column.
    • Motivation to Combine: A POSA would combine El Rassi's teachings on dual-salt benefits with Pharmacia's guidance on scaling up HIC processes for industrial use. Pharmacia teaches that for preparative-scale purification, unlike lab-scale, it is necessary to mix the protein with the salt solution before loading to prevent the large sample volume from diluting the salt on the column and causing premature elution. This routine modification would lead directly to the claimed process.
    • Expectation of Success: A POSA would have reasonably expected that scaling up El Rassi's process according to the standard techniques described in Pharmacia would result in increased DBC. This is because the known correlation between increased retention (taught by El Rassi) and increased DBC would be expected to hold true in a properly scaled-up industrial process.

  • Additional Grounds: Petitioner asserted anticipation of claims 1 and 10 over Memoli (a 1975 journal article) and obviousness of all challenged claims over Memoli in view of Pharmacia and a POSA's general knowledge.

4. Key Claim Construction Positions

  • "such that the dynamic capacity of the column is increased for the protein": Petitioner argued this term is indefinite under the Patent Owner's proposed construction in co-pending litigation. The proposed construction requires comparison to a single salt at a "higher concentration" without specifying how much higher, rendering the claim scope unclear. For the purposes of the IPR, Petitioner adopted Patent Owner's constructions to demonstrate invalidity even under that framework.
  • "mixing a preparation containing the protein with a combination of a first salt and a second salt": Petitioner argued for its plain and ordinary meaning, contending that Patent Owner's proposed construction (requiring "no other salts") would render the claims indefinite and improperly import limitations.

5. Arguments Regarding Discretionary Denial

  • Petitioner argued against discretionary denial under Fintiv. It contended that the trial date in the parallel district court case, while scheduled one month before the Final Written Decision deadline, was likely to be postponed. More critically, Petitioner stipulated that if the IPR is instituted, it will not pursue in the district court litigation any invalidity ground that was raised or reasonably could have been raised in the IPR. Petitioner asserted this stipulation eliminates concerns of duplicative efforts and ensures the IPR is a true alternative to district court litigation, weighing strongly against discretionary denial.

6. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1, 2, 4, 8, 10, and 11 of the ’707 patent as unpatentable.