Beckman Coulter Inc v. Sirigen II Ltd

1. Case Identification

• Case #: IPR2022-01205
• Patent #: 10,955,417
• Filed: June 28, 2022
• Petitioner(s): Beckman Coulter, Inc.
• Patent Owner(s): Sirigen II Limited
• Challenged Claims: 1-18 and 20

2. Patent Overview

• Title: Water-Soluble Conjugated Polymers
• Brief Description: The ’417 patent discloses water-soluble, fluorescent conjugated polymers for use as probes in biological assays, such as flow cytometry. The polymers are defined by a generic structure ("Formula Ar") comprising various repeating units, including an aryl unit (Ar) substituted with an ethylene glycol oligomer side group to enhance water solubility, and end groups (G1, G2) for conjugation to biomolecules like antibodies.

3. Grounds for Unpatentability

Ground 1: Anticipation over Xue - Claims 1-6 and 11-16 are anticipated by Xue under 35 U.S.C. §102.

• Prior Art Relied Upon: Xue (a 2009 journal article titled Highly Water-Soluble, Fluorescent, Conjugated Fluorene-Based Glycopolymers...).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Xue's "Polymer B" and "Polymer C" inherently disclose every limitation of the challenged claims. These polymers are described as water-soluble, alternating copolymers with a fluorene unit (the claimed "Ar" unit) and a phenyl unit (the claimed "MU" or polymer modifying unit). Petitioner asserted that the fluorene units are substituted with polyethylene glycol (PEG) side chains, meeting the "ethylene glycol oligomer side group" limitation. Furthermore, the polymers are terminated with sugar groups (β-glucose or α-mannose), which Petitioner contended are "conjugated biomolecules" attached at the polymer ends, satisfying the requirements for the G1/G2 end groups in claims 1 and 11.
  • Key Aspects: The argument relies on the inherent result of Xue's stochastic polymerization process, which would produce a population of polymer molecules where at least some terminate with a fluorene unit bearing a biomolecule, thus satisfying the claim limitations.

Ground 2: Anticipation over Gaylord - Claims 11-17 are anticipated by Gaylord under 35 U.S.C. §102.

• Prior Art Relied Upon: Gaylord (Application # 2008/0293164).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Gaylord, a patent application from the same inventors, discloses the entire claimed invention. Gaylord's general formula for "multichromophores" and specific examples ("Gaylord Polymer 1" and "Gaylord Polymer 2") were alleged to satisfy the claimed Formula Ar. Gaylord expressly teaches fluorene-based polymers (the "Ar" unit) substituted with non-ionic PEG side chains for water solubility. It also teaches incorporating "bandgap-lowering" units (the "MU" unit) and "bioconjugation sites" within internal linkers (the "L1/L2" units). Petitioner contended that Gaylord's use of Suzuki coupling for polymerization would result in polymer ends (G1/G2) terminated with hydrogen, halogen, or boronic acid/ester groups, all of which fall within the claimed options for the end groups.

Ground 3: Obviousness over Gaylord Combination - Claims 1-10, 18, and 20 are obvious over Gaylord in view of Gauthier, Gordon, or Lou, and further in view of Haugland.

• Prior Art Relied Upon: Gaylord (Application # 2008/0293164), Gauthier (a 2008 review article), Gordon (a 1999 journal article), Lou (a 2007 journal article), and Haugland (a 2000 book chapter).

• Core Argument for this Ground:

  • Prior Art Mapping: Petitioner argued that Gaylord discloses the foundational water-soluble conjugated polymer. The key difference between the polymer disclosed in Gaylord and independent claim 1 is the requirement that at least one end group (G1 or G2) comprises a conjugated biomolecule. Gaylord primarily teaches attaching biomolecules to internal linkers.
  • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine these references to improve upon Gaylord's polymer design. Gauthier, Gordon, and Lou were cited to show that end-group functionalization was a well-known, alternative strategy for attaching molecules to polymers. A POSITA would have been motivated to place the antibody attachment site at the polymer's end, rather than on an internal linker, to ensure a 1:1 fluorophore-to-antibody ratio. Haugland teaches that optimizing this ratio is desirable, and end-labeling prevents a single polymer (fluorophore) from cross-linking multiple antibodies, which could occur with side-chain attachment.
  • Expectation of Success: A POSITA would have had a high expectation of success because end-group functionalization was one of only two primary, predictable strategies for attaching molecules to polymers, and the necessary chemical techniques were conventional.

• Additional Grounds: Petitioner asserted additional obviousness challenges, including that claims 11-17 are obvious over Gaylord in view of Bazan, and that claims 7 and 17 are obvious over combinations including Gaylord, Zalipsky, Hermanson, Xue, and Sumranjit based on routine optimization of PEG side chain length and composition.

4. Key Claim Construction Positions

• Petitioner argued that the claim term "the polymer comprises at least 1 functional group ... within G1, G2, L1 or L2, or a conjugated organic dye or biomolecule" should be interpreted with its plain meaning. Specifically, Petitioner contended that the locational limitation "within G1, G2, L1 or L2" applies only to the list of functional groups and does not apply to "a conjugated organic dye or biomolecule." Therefore, the biomolecule could be located anywhere on the polymer. This construction is central to the anticipation arguments, as the biomolecules in the prior art are not necessarily within a specific, defined G1/G2 group structure.

5. Key Technical Contentions (Beyond Claim Construction)

• Petitioner dedicated significant argument to contending that the ’417 patent is not entitled to its claimed priority date of January 19, 2010. It was argued that the ’379 provisional application lacks adequate written description under 35 U.S.C. §112 to support the full scope of the challenged claims. Specifically, Petitioner asserted the provisional fails to disclose the generic Formula Ar, the claimed mol % ranges for the polymer units (a, b, c, d), or a representative number of species within the claimed genus. This contention is critical, as it establishes a later effective filing date, thereby qualifying references like Xue as prior art under §102(b).

6. Arguments Regarding Discretionary Denial

• Petitioner argued that the Board should not exercise its discretion to deny institution under 35 U.S.C. §325(d). The primary basis for this argument was that the main prior art reference, Xue, was never presented to or considered by the Examiner during the prosecution of the ’417 patent or any related family member. Regarding the Gaylord reference, Petitioner argued that although it was cited in an Information Disclosure Statement (IDS) during prosecution of the application leading to the ’417 patent, it was never substantively discussed. Petitioner further alleged that in related prosecutions where Gaylord was considered, the Examiner made material errors in its analysis, warranting reconsideration by the Board.

7. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claims 1-18 and 20 of the ’417 patent as unpatentable.