PTAB

IPR2018-00402

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 ’401 patent describes a flexible, non-radioactive implantable strand for delivering a therapeutic agent to a subject. The strand includes a marker component, such as a radiopaque material, to allow for its position to be determined within a target tissue using external imaging.

3. Grounds for Unpatentability

Ground 1: Claims 1-5 and 9-25 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 taught most of the claimed elements, including a bioabsorbable, tubular implant for brachytherapy containing a therapeutic agent and a radiopaque marker to aid visualization. However, Zamora’s device also included a radioisotope. Petitioner asserted that Brem taught a non-radioactive polymer implant for localized delivery of chemotherapeutic agents, thus supplying the “non-radioactive” limitation of the challenged claims. Brem also taught that its implants could be flexible.
    • Motivation to Combine: A POSITA would combine Zamora and Brem as both relate to implantable polymer devices for cancer treatment and address targeted drug delivery. The primary motivation would be to modify Zamora’s device to be non-radioactive, as taught by Brem, to provide greater flexibility in treatment protocols (e.g., chemotherapy without concurrent radiation) and to avoid the known safety hazards of handling radioactive materials. A secondary motivation would be to add Zamora’s radiopaque marker to Brem’s non-radioactive implant to solve the known problem of tracking an implant’s location within the body.
    • Expectation of Success: A POSITA would have a reasonable expectation of success in this combination due to the significant overlap in the technologies, including the use of similar polymers and therapeutic agents for the same purpose (cancer treatment). Petitioner noted that the Board, in a related proceeding, had already found it was optional and obvious in the art to include or exclude a radionuclide in an implantable device.

Ground 2: Claims 1-5 and 9-25 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 asserted that to the extent the combination of Zamora and Brem was deemed insufficient, De Nijs provided the missing teachings. De Nijs taught a non-radioactive, cylindrical polymer implant for delivering contraceptive hormones. Petitioner argued De Nijs explicitly disclosed an implant with at least one open end to allow an agent to pass out of its hollow interior, a limitation of claims 1 and 14. Further, De Nijs taught specific implant dimensions (e.g., 1-4 cm length, ~2 mm diameter) that fall within the ranges recited in dependent claims 2 and 3.
    • Motivation to Combine: A POSITA would be motivated to incorporate the teachings of De Nijs into the Zamora/Brem combination because all three references are in the same field of endeavor: biocompatible polymer implants for controlled drug delivery. Both Zamora and Brem acknowledged contraceptive implants as relevant prior art. The similar geometries (elongated cylinders) and purpose would lead a POSITA to look to De Nijs for specific design choices regarding implant dimensions and drug-release configurations.
    • Expectation of Success: A POSITA would expect to successfully combine these references, as De Nijs’s teachings on specific dimensions and open-ended structures represented known design parameters for the type of drug-eluting implants disclosed in Zamora and Brem.

Ground 3: Claims 1-5, 9-10, 13-21, and 23-25 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 provided an alternative invalidity theory based on art focused on contraceptive implants. Petitioner contended that De Nijs, as the primary reference, taught a flexible, non-radioactive, cylindrical implant containing a therapeutic agent (hormone) within a hollow polymer structure, meeting nearly all claim limitations except for an imageable marker. Schopflin was asserted to cure this deficiency by expressly teaching a non-radioactive implant that includes a "radiopaque amount of barium sulfate" for the specific purpose of "improved X-ray localization in the body."
    • Motivation to Combine: A POSITA would combine De Nijs and Schopflin because both disclose polymer implants for the same application: contraceptive hormone delivery. The motivation would be to add Schopflin's known radiopaque marker to De Nijs's implant to solve the well-understood problem of locating and tracking an implant within the body. This was particularly relevant for the non-biodegradable implants of De Nijs, which would eventually require removal and were known to be at risk of migrating.
    • Expectation of Success: A POSITA would have a high expectation of success due to the substantial technical overlap between the references. Both taught non-radioactive, cylindrical implants of similar dimensions (e.g., 1.5-2 mm diameter, 1-4 cm length), used for the same purpose, and suitable for implantation with a hypodermic needle.

4. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1-5 and 9-25 of the ’401 patent as unpatentable.