PTAB

IPR2018-00393

Merck Sharp & Dohme Corp v. Microspherix LLC

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Key Events
Petition

1. Case Identification

2. Patent Overview

  • Title: Drug-Eluting Implantable Strand with Radiopaque Marker
  • Brief Description: The ’402 patent discloses an implantable, non-radioactive drug delivery strand for administration of a therapeutic agent. The strand comprises the agent and a radiopaque material encapsulated in a biocompatible polymeric component, allowing the strand's position to be determined by external imaging.

3. Grounds for Unpatentability

Ground 1: Claims 1-19 are obvious over Zamora in view of Brem

  • Prior Art Relied Upon: Zamora (6,575,888) and Brem (5,626,862).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Zamora taught nearly all limitations of the challenged claims, including a bioabsorbable brachytherapy device in the form of a strand or rod, a therapeutic agent, a polymeric housing, and a radiopaque material encapsulated within the housing. The primary element Zamora did not teach was the absence of a radioisotope. Petitioner asserted that Brem remedied this deficiency by teaching a non-radioactive, polymer-based implant for the localized delivery of a chemotherapeutic agent, which could optionally be combined with radiation therapy. The combination of Zamora's structural features with Brem's non-radioactive nature allegedly rendered the claims obvious.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSA) would combine Zamora and Brem because both relate to implantable polymer devices for cancer treatment. A POSA would have been motivated to modify Zamora's device to be non-radioactive as taught by Brem for several reasons: (1) to provide greater flexibility in treatment protocols by decoupling chemotherapy from mandatory concurrent radiation therapy; (2) to avoid the known safety hazards associated with handling radioactive materials; and (3) to incorporate Zamora's radiopaque marker into Brem's implant to improve tracking and placement verification.
    • Expectation of Success: A POSA would have had a high expectation of success. The references use similar polymers and therapeutic agents for the same purpose. Brem's teaching that radiation is an optional addition to its therapy confirmed that removing the radioisotope from Zamora's device was a predictable and straightforward modification that would result in a functional, non-radioactive drug-eluting implant.

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 (6,575,888), Brem (5,626,862), and De Nijs (5,150,718).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground built upon the combination of Zamora and Brem. Petitioner argued that to the extent the primary combination was deemed insufficient to teach certain dependent claim limitations, De Nijs provided the missing elements. De Nijs taught a non-radioactive, cylindrical polymer implant for hormone delivery, expressly disclosing features such as open ends (teaching "pores or cavities" of claim 6 and "open ends" of claim 9) and specific dimensions falling within the ranges claimed (e.g., diameter between 0.5 and 3 mm and length of 40 mm).
    • Motivation to Combine: A POSA would combine De Nijs with the Zamora/Brem combination because all three references are in the same field of endeavor: biocompatible polymer implants for controlled drug delivery. Zamora and Brem themselves refer to contraceptive hormone implants like those in De Nijs as relevant background art. A POSA would look to analogous art like De Nijs for known and successful implant configurations and dimensions, making it an obvious source for design choices.
    • Expectation of Success: Success was expected because the technologies are highly similar. The implant geometry (filled cylinder), composition (biocompatible polymer), and purpose (drug delivery) of the Zamora/Brem combination were analogous to De Nijs, ensuring that incorporating De Nijs's specific dimensional and structural features would be a predictable modification.

Ground 3: Claims 1-19 are obvious over De Nijs in view of Schopflin

  • Prior Art Relied Upon: De Nijs (5,150,718) and Schopflin (4,012,497).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground provided an alternative invalidity theory based entirely on contraceptive implant art. Petitioner contended that De Nijs taught every limitation of the claims except for the radiopaque marker. De Nijs disclosed a non-radioactive, cylindrical, polymer-based implant (e.g., ethylene-vinyl acetate copolymer) that elutes a therapeutic agent (a hormone). Schopflin, in the same field, taught that a radiopaque material like barium sulfate could be blended into a similar polymer implant to allow for "improved X-ray localization in the body."
    • Motivation to Combine: A POSA would combine these references because they are in the same field (implantable contraceptive hormone delivery), describe nearly identical implant configurations, and solve the same general problem. A POSA would have been motivated to add Schopflin's radiopaque marker to De Nijs's implant for the known benefit of tracking its location. This was particularly relevant for the non-biodegradable implants of De Nijs, which would eventually require removal and could be difficult to locate if they migrated.
    • Expectation of Success: A POSA would have had a strong expectation of success due to the substantial overlap between the references. Both taught non-radioactive, cylindrical strands of similar dimensions (approx. 1.5-2 mm diameter, 1-4 cm length) delivering the same class of therapeutic agent. Adding a known, inert radiopaque marker from Schopflin to the similar device of De Nijs was a simple, predictable combination.

4. Key Claim Construction Positions

  • "encapsulated": Petitioner proposed that the broadest reasonable interpretation of "encapsulated" is "enclosed."
    • Argument: This construction was supported by the dictionary definition ("to enclose in or as if in a capsule") and the patent's own usage. The specification consistently used the term with the preposition "in" (e.g., "encapsulated in a biocompatible component") and equated "encapsulating" with "containing," indicating the term's plain meaning of enclosing or surrounding.

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.