Beckman Coulter Inc v. Sirigen II Ltd

1. Case Identification

• Case #: IPR2022-01208
• Patent #: 8,575,303
• Filed: June 29, 2022
• Petitioner(s): Beckman Coulter, Inc.
• Patent Owner(s): Sirigen II Limited
• Challenged Claims: 1-15, 17-37, and 40-41

2. Patent Overview

• Title: Water Soluble Conjugated Polymers
• Brief Description: The ’303 patent discloses a class of water-soluble conjugated polymers intended for use as fluorescent dyes in biological assays. The patent claims a generic polymer structure (Formula Ia) comprising a fluorene backbone, non-ionic side groups (e.g., polyethylene glycol or PEG) to impart water solubility, and various optional modifying, linking, and end-group units.

3. Grounds for Unpatentability

Ground 1: Anticipation - Claims 1, 4-5, 7, 13, 23-24, 27, 35-37, and 40 are anticipated by Xue.

• Prior Art Relied Upon: Xue (Cuihua Xue et al., a 2009 journal article).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Xue discloses water-soluble, fluorene-based conjugated polymers, specifically "Polymers B and C," that meet every limitation of the challenged claims. Petitioner asserted that Polymers B and C are alternating copolymers of fluorene and phenyl units, which satisfy the claimed Formula (Ia). The fluorene units are substituted with PEG chains, meeting the "non-ionic side group" (R) limitation for water solubility. The phenyl repeat unit functions as the claimed "polymer modifying unit" (MU). Because the claimed linker units (L1 and L2) are optional, their absence in Xue does not preclude anticipation. Petitioner further contended that the stochastic polymerization process in Xue results in polymer end-groups (G1 and G2) that are either fluorene (with a sugar biomolecule attached via a thiol group) or phenyl (terminating in hydrogen or a boronic acid/ester), all of which fall within the claimed options. The molar percentages and polymer length disclosed in Xue also fall within the claimed ranges.
  • Key Aspects: Petitioner contended that Xue’s explicit disclosure of highly water-soluble polymers for detecting E. coli provides a direct structural and functional anticipation of the patent’s core claims.

Ground 2: Anticipation - Claims 1-2, 4-5, 7, 10, 12, 14-15, 17, 20-24, 26-37, and 40-41 are anticipated by Gaylord.

• Prior Art Relied Upon: Gaylord (Application # 2008/0293164).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Gaylord, an application from the same patent owner with overlapping inventors, describes the same class of water-soluble conjugated polymers and anticipates the challenged claims. Gaylord’s general formula and specific examples, "Gaylord Polymer 1" and "Gaylord Polymer 2," were alleged to satisfy the claimed Formula (Ia). These polymers contain fluorene units substituted with non-ionic PEG side groups (R), meeting the solubility requirement. Gaylord explicitly teaches using "low bandgap repeat units" (e.g., difluorophenyl), which function as the claimed "polymer modifying unit" (MU), and teaches the inclusion of linker units with bioconjugation sites (e.g., a phenyl group with a maleimide-terminated pendant chain), which meet the L1 and L2 limitations. Petitioner asserted Gaylord’s disclosure of Suzuki coupling polymerization results in end groups (G1 and G2) of hydrogen, halogen, or boronic acid/esters, satisfying that limitation. The molar percentages for the various units, either explicitly or through incorporation by reference, were also alleged to fall within the claimed ranges.

Ground 3: Obviousness over Gaylord in view of Bazan and others - Claims 1-2, 4-5, 7, 10, 12, 14-15, 17, 20-24, 26-37, and 40-41 are obvious over Gaylord, optionally in view of Bazan.

• Prior Art Relied Upon: Gaylord (Application # 2008/0293164) and Bazan (Application # 2006/0183140).

• Core Argument for this Ground:

  • Prior Art Mapping: Petitioner argued that even if Gaylord does not anticipate every claim, it provides the foundational disclosure for the claimed invention. Gaylord teaches the core polymer structure, including fluorene units, non-ionic PEG side groups, low bandgap modifying units (MU), and bioconjugation linkers (L1/L2).
  • Motivation to Combine: Petitioner asserted that a Person of Ordinary Skill in the Art (POSITA) would have been motivated to combine Gaylord with Bazan because Gaylord expressly incorporates Bazan by reference for "details related to multichromophores" and their synthesis. This express instruction would lead a POSITA to consult Bazan for specific parameters, such as the molar percentage ranges for the various repeat units, to optimize polymer properties like bandgap and water solubility. Petitioner also argued a POSITA would be motivated to select non-ionic side groups, as taught in Gaylord, to avoid the known problem of non-specific binding associated with charged groups in biological assays.
  • Expectation of Success: A POSITA would have had a reasonable expectation of success because combining the teachings involved applying known principles (e.g., adjusting monomer ratios) to achieve predictable results (e.g., modified polymer properties) using established synthetic chemistries disclosed in the references.

• Additional Grounds: Petitioner asserted additional obviousness challenges, including claims 10 and 41 as obvious over Xue in view of Gaylord, and claim 25 as obvious over Xue in view of Sumranjit. Further grounds combined Gaylord with various secondary references (e.g., Gauthier, Gordon, Lou, Haugland, Hermanson) to teach specific dependent claim limitations, such as particular end-group structures and methods of conjugation to antibodies.

4. Key Technical Contentions (Beyond Claim Construction)

• Disputed Priority Date: Petitioner argued the ’303 patent is not entitled to the priority date of its provisional application (’379 provisional). Petitioner contended the provisional lacks adequate written description for the claims, as it fails to disclose the recited Formula (Ia), any species falling within the formula, or the claimed molar percentage ranges for the polymer’s constituent units. This contention is critical, as a later priority date makes Xue (published in 2009) prior art under pre-AIA 35 U.S.C. §102(b).

5. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial under §325(d) would be inappropriate. The primary reference Xue was never presented to or considered by the Examiner during prosecution. Regarding Gaylord, Petitioner asserted that although it was cited in an IDS for the ’303 patent’s application and considered in the prosecution of related family members with narrower claims, the Examiner never substantively analyzed Gaylord against the broader claims of the ’303 patent. Furthermore, Petitioner argued the Examiner materially erred in its previous evaluations of Gaylord in the related applications, warranting reconsideration.

6. Relief Requested

• Petitioner requests institution of inter partes review and cancellation of claims 1-15, 17-37, and 40-41 of the ’303 patent as unpatentable.