PTAB

IPR2018-00602

Merck Sharp & Dohme Corp. v. Microspherix LLC

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1. Case Identification

2. Patent Overview

  • Title: Implantable Drug-Eluting Seed with Radiopaque Marker
  • Brief Description: The ’835 patent discloses an implantable "seed" for localized therapy, such as brachytherapy. The seed contains a therapeutic or diagnostic agent and includes a radiopaque marker component to allow for determination of its position within a subject's body.

3. Grounds for Unpatentability

Ground 1: Anticipation of Claims 1-4, 9-12, and 15-19 by Zamora

  • Prior Art Relied Upon: Zamora (Patent 6,575,888).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Zamora teaches every element of the challenged claims. Zamora describes a bioabsorbable brachytherapy device comprising a tubular polymeric housing (a "substantially continuous wall bounding a hollow interior") that contains a radioactive material and may further include a radiopaque medium (a "marker component") and therapeutic drugs (a "therapeutic agent"). Petitioner contended that Zamora’s tubular device, which can be sealed or left with at least one open end, meets the limitations for an implantable "seed" with an opening to allow an agent to pass out.
    • Key Aspects: The anticipation argument relied on Zamora’s explicit disclosure of combining a therapeutic drug, a radiopaque marker, and a polymeric housing in a single implantable brachytherapy device.

Ground 2: Obviousness of Claims 1-4, 9-12, and 14-20 over Zamora in view of Brem

  • Prior Art Relied Upon: Zamora (Patent 6,575,888) and Brem (Patent 5,626,862).
  • Core Argument for this Ground:
    • Prior Art Mapping: To the extent Zamora was found not to anticipate every limitation, Petitioner asserted the claims are obvious over Zamora combined with Brem. Brem teaches localized delivery of chemotherapeutic agents from polymer reservoirs, including those with a "micropore lattice" that allows drug release via diffusion. Petitioner argued Brem’s disclosure of drug release through a porous polymer structure explicitly teaches the "plurality of pores" limitation of claim 14, which may not be expressly disclosed in Zamora.
    • Motivation to Combine: A POSITA would combine Zamora and Brem because both are directed to implantable polymer devices for cancer treatment. A POSITA would be motivated to incorporate Zamora’s radiopaque marker into Brem’s reservoir design to gain the known benefit of tracking the implant's location, while using Brem’s diffusion-based release mechanism to achieve a more constant drug release rate.
    • Expectation of Success: A POSITA would have a reasonable expectation of success because both references teach implant embodiments with a polymer housing surrounding an interior reservoir, a well-known design paradigm. The similar applications and materials would make the combination straightforward.

Ground 3: Obviousness of Claims 1-4, 10, 14, 16-17, and 20 over De Nijs in view of Schopflin

  • Prior Art Relied Upon: De Nijs (Patent 5,150,718) and Schopflin (Patent 4,012,497).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground addresses the ’835 patent’s applicability to non-brachytherapy devices, such as contraceptive implants, which Patent Owner asserted in related litigation. De Nijs teaches a rod-shaped contraceptive implant (a "seed") comprising a core material with a hormone (a "therapeutic agent") encased in a polymer membrane (a "substantially continuous wall"). However, De Nijs does not teach an imageable marker. Schopflin remedies this deficiency by teaching the inclusion of a radiopaque agent, such as barium sulfate, into similar polymer drug-delivery implants for "improved X-ray localization."
    • Motivation to Combine: A POSITA would combine the references as both relate to long-term, implantable polymer drug-delivery systems. It would have been obvious to add Schopflin's radiopaque marker to De Nijs's implant to solve the known problem of locating non-biodegradable implants for removal, a significant concern for contraceptive devices that may migrate over time.
    • Expectation of Success: A POSITA would expect success due to the substantial overlap between the references. Both teach cylindrical, polymer-based implants of similar dimensions for long-term hormone release, making the addition of a known radiopaque material a simple and predictable modification.

  • Additional Grounds: Petitioner asserted an additional obviousness challenge (Ground 4) against claims 14 and 20 based on the combination of De Nijs, Schopflin, and Brem, arguing Brem's teachings on porous polymers (specifically EVA) further support the "plurality of pores/openings" limitations.

4. Key Claim Construction Positions

  • Petitioner argued that the broadest reasonable interpretation (BRI) for the term "seed," recited in the preamble of all challenged claims, should be an implant with a size and shape suitable for passing through a needle, including elongated "cylinder (or rod)" structures up to 40 mm long. This construction was based on language in the ’835 patent’s specification and, critically, on the Patent Owner's own position in a parallel district court infringement suit where it accused a 4 cm long contraceptive rod of infringing the claims. Adopting this broad construction was central to Petitioner's ability to rely on prior art for contraceptive rods (e.g., De Nijs), which are structurally analogous to the accused product but distinct from traditional, smaller brachytherapy seeds.

5. Arguments Regarding Discretionary Denial

  • Petitioner argued that institution was warranted because the asserted grounds were not redundant and relied on prior art that had not been substantively considered during prosecution. It was argued that the grounds presented distinct invalidity theories based on different fields of use (brachytherapy vs. contraception), reflecting the broad scope of the claims asserted by the Patent Owner. Furthermore, Petitioner noted that key references, such as Schopflin, were never cited by the Examiner. While Zamora was considered in a related application, it was not discussed in the prosecution history of the ’835 patent itself, indicating the Examiner had not previously evaluated the specific anticipation arguments presented in the petition.

6. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-4, 9-12, and 14-20 of the ’835 patent as unpatentable under 35 U.S.C. §§ 102 and 103.