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IPR2022-00041

JSR Corp v. Cytiva BioProcess R&D Ab

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Petition
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1. Case Identification

2. Patent Overview

  • Title: Process for Isolating Target Compounds
  • Brief Description: The ’142 patent is directed to a process for isolating target compounds using an affinity chromatography matrix. The matrix comprises a ligand based on the naturally-occurring C domain of Staphylococcal protein A (SPA), where the ligand is engineered with a G29A mutation (glycine at position 29 replaced by alanine) to improve alkali-stability for cleaning-in-place procedures.

3. Grounds for Unpatentability

Ground 1: Obviousness over Linhult and Abrahmsén - Claims 1-4, 12, 14-17, 25, and 27-30 are obvious over Linhult in view of Abrahmsén.

  • Prior Art Relied Upon: Linhult (a 2004 journal article) and Abrahmsén (Patent 5,143,844).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Linhult disclosed the fundamental elements of the claimed process, including using SPA-based chromatography matrices to isolate target compounds. Linhult specifically identified the asparagine-glycine sequence at positions 28-29 (Asn28-Gly29) as the "most sensitive amino acid sequence to alkaline conditions" and acknowledged that a G29A mutation was a known solution to this problem. Although Linhult did not explicitly describe a ligand based on the C domain with a G29A mutation (a "C(G29A)-based SPA ligand"), Abrahmsén did. Abrahmsén expressly taught making a G29A mutation to any of the SPA domains, including the C domain, to improve stability.
    • Motivation to Combine: A POSITA would combine Linhult's known problem of alkali sensitivity with Abrahmsén's explicit solution. Petitioner asserted a POSITA would have been motivated to apply the G29A mutation taught in Abrahmsén to the C-domain-based chromatography process described in Linhult to achieve the predictable benefit of increased alkali-stability, a desirable property for industrial-scale purification. Linhult itself stated that relying on C-domain-specific residues to improve stability was an "obvious" decision.
    • Expectation of Success: Abrahmsén confirmed that the G29A mutation "would not interfere with folding [of SPA] or binding to [antibodies]," which provided a POSITA with a reasonable expectation of success in making the combination without losing the ligand's essential function.

Ground 2: Obviousness over Linhult and Hober - Claims 1-7, 10-20, and 23-30 are obvious over Linhult in view of Hober.

  • Prior Art Relied Upon: Linhult (a 2004 journal article) and Hober (WO 03/080655).

  • Core Argument for this Ground:

    • Prior Art Mapping: As in Ground 1, Linhult provided the foundational chromatography process and identified the alkali-sensitivity of the Asn28-Gly29 sequence. Hober, like Abrahmsén, provided the missing element. Hober taught that a G29A mutation is "advantageous for structural stability reasons" and could be performed on any of the SPA domains, including the C domain. Hober further disclosed data from an alkali-stability study on Z-domain ligands (which contain a G29A mutation on the B domain) that incorporated C-domain-specific residues, demonstrating their stability.
    • Motivation to Combine: A POSITA would combine Linhult's teaching of the problem with Hober's clear disclosure of the solution. The motivation was to create an alkali-stabilized ligand by avoiding the troublesome Asn28-Gly29 sequence. Hober's data showing that ligands with a G29A mutation achieved at least 95% binding capacity after 5 hours in 0.5M NaOH—matching a limitation in dependent claims 3 and 16—would have further motivated the combination to achieve a commercially desirable, reusable chromatography matrix.
    • Expectation of Success: Petitioner argued that combining known elements (Linhult's process, Hober's mutation) for a predictable purpose (increased stability) would lead to a reasonable expectation of success. Hober's stability data for similar ligands would have reinforced this expectation.

  • Additional Grounds: Petitioner asserted that claims 1-7, 10-20, and 23-30 are also obvious over the three-way combination of Linhult, Abrahmsén, and Hober. A fourth ground asserted the same claims are obvious over Abrahmsén in view of Hober, arguing a POSITA would apply the specific C(G29A) ligand from Abrahmsén to the general affinity chromatography context taught by Hober.

4. Key Claim Construction Positions

  • The petition proceeded based on the Patent Owner's implicit construction from related district court litigation.
  • Petitioner argued that the claim term "the ligand comprising at least two polypeptides" refers to a multimeric ligand (e.g., a dimer, tetramer, or pentamer) comprised of multiple polypeptide monomers. This construction was central to mapping prior art that disclosed the multimerization of SPA domains to create affinity ligands.

5. Arguments Regarding Discretionary Denial

  • §314(a) (Fintiv): Petitioner argued against discretionary denial under Fintiv, stating that the parallel district court case was in its early stages, with a trial date more than two years after the petition's filing. Petitioner asserted that a stay of the litigation was likely upon institution, and that because invalidity contentions had not yet been presented in court, there was no significant overlap in arguments that would favor denial.
  • §325(d): Petitioner contended that denial under §325(d) was inappropriate because the core prior art references, Linhult and Abrahmsén, were never considered during the prosecution of the ’142 patent. While Hober was cited in an Information Disclosure Statement (IDS), it was never used in a rejection, meaning the Examiner did not substantively review its teachings. Therefore, the petition raised new arguments based on art not previously considered by the USPTO.

6. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-7, 10-20, and 23-30 of the ’142 patent as unpatentable.