PTAB

IPR2018-00393

MERCK SHARP & DOHME CORP. v. Microspherix LLC

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1. Case Identification

2. Patent Overview

  • Title: Imageable, Drug-Eluting Implantable Strands
  • Brief Description: The ’402 patent discloses a non-radioactive, drug-eluting implantable strand containing a radiopaque marker. The marker allows the strand's location to be identified within a patient's body using external imaging techniques like X-rays.

3. Grounds for Unpatentability

Ground 1: Claims 1-19 are obvious 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: Petitioner argued that Zamora teaches most of the challenged claim limitations, including a bioabsorbable brachytherapy device in the form of a rod or cylinder. This device comprises a therapeutic agent, a biocompatible polymer, and a radiopaque material encapsulated within the polymer housing. The key missing element in Zamora is the explicit exclusion of a radioisotope. Petitioner asserted that Brem, which discloses a non-radioactive implant for localized delivery of chemotherapeutic agents, remedies this deficiency. Brem teaches implants that release a drug over time and explicitly states that radiation therapy is optional, thereby teaching a non-radioactive therapeutic implant.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine Zamora and Brem because both are directed to the same field of implantable polymer devices for cancer treatment. Petitioner contended a POSITA would be motivated to modify Zamora’s device to be non-radioactive as taught by Brem to gain flexibility in treatment protocols (i.e., separating chemotherapy from radiotherapy) and to avoid the known safety hazards of handling radioactive materials. Conversely, a POSITA would add Zamora's radiopaque marker to Brem's implant to allow for verification of placement and tracking within the body, a known solution for a known problem.
    • Expectation of Success: A POSITA would have a reasonable expectation of success in removing the radioisotope from Zamora’s device. Brem explicitly teaches that its therapeutic implants may optionally be combined with radiation, demonstrating the feasibility of decoupling the two. Petitioner noted that the Patent Trial and Appeal Board (PTAB) in a related proceeding had already found it was recognized in the art that including a radionuclide in an implantable device was optional.

Ground 2: Claims 6-9, 11-12, 14, and 18 are obvious over Zamora in view of Brem and De Nijs.

  • Prior Art Relied Upon: Zamora (Patent 6,575,888), Brem (Patent 5,626,862), and De Nijs (Patent 5,150,718).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground built upon the combination of Zamora and Brem, adding De Nijs to provide teachings for specific limitations in dependent claims. Petitioner argued that to the extent Zamora and Brem do not explicitly teach limitations such as a rod with pores, cavities, or open ends (claims 6 and 9) or specific dimensions like a 40 mm length (claims 7, 11, 14, and 18), De Nijs provides these teachings. De Nijs discloses a non-radioactive, cylindrical contraceptive implant with open ends and teaches specific dimensions, including a length of up to 4 cm (40 mm) and a diameter of about 2 mm.
    • Motivation to Combine: A POSITA would be motivated to incorporate the teachings of De Nijs because it is in the same field of endeavor (biocompatible polymer implants for controlled drug delivery). Petitioner pointed out that both Zamora and Brem acknowledge contraceptive implants as relevant background art. Given the similar geometries and purpose, a POSITA would look to a reference like De Nijs for teachings on specific configurations and dimensions to apply to the non-radioactive, radiopaque implant derived from Zamora and Brem.
    • Expectation of Success: The significant overlap in implant technology (biocompatible polymers, drug delivery, cylindrical shape) between the Zamora/Brem combination and De Nijs would provide a POSITA with a reasonable expectation that the specific configurations from De Nijs could be successfully incorporated.

Ground 3: Claims 1-19 are obvious 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 presented an alternative invalidity theory based on contraceptive implant technology. Petitioner asserted De Nijs teaches nearly every claim limitation, including a non-radioactive, cylindrical, rod-like implant made of a biocompatible polymer (EVA), delivering a therapeutic agent (a hormone), and having a polymeric coating. The primary element De Nijs lacks is a radiopaque material. Petitioner argued Schopflin fills this gap by teaching the inclusion of a radiopaque material (barium sulfate) into a similar non-radioactive, hormone-releasing silicone implant for the express purpose of "improved X-ray localization in the body."
    • Motivation to Combine: A POSITA would combine De Nijs and Schopflin because both references are directed to the same application: non-radioactive, long-term contraceptive implants. A POSITA working with De Nijs's non-biodegradable implant, which must eventually be located and removed, would be motivated to incorporate Schopflin's known solution of adding a radiopaque marker to track the implant's location and mitigate the known risk of migration.
    • Expectation of Success: Petitioner argued for a high expectation of success due to the substantial overlap between the references. Both teach non-radioactive, cylindrical implants of similar dimensions (e.g., ~1.5-2 mm diameter, 1-4 cm length) that deliver contraceptive hormones and are covered by a polymeric coating. This high degree of similarity would lead a POSITA to expect that Schopflin's radiopaque feature could be successfully integrated into De Nijs's device.

4. Key Claim Construction Positions

  • "encapsulated": Petitioner argued that for the purposes of this IPR, the broadest reasonable interpretation of "encapsulated" (recited in claims 1, 10, and 16) is "enclosed." This interpretation is based on dictionary definitions and the patent’s use of the term interchangeably with "containing" when describing the placement of a therapeutic component within a strand. This construction is important for mapping prior art that teaches admixing or blending a radiopaque material with a polymer, which would then be considered "enclosed" by the polymer.

5. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1-19 of the ’402 patent as unpatentable under 35 U.S.C. §103.