PTAB

IPR2018-00402

MERCK SHARP & DOHME CORP. v. Microspherix LLC

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1. Case Identification

2. Patent Overview

  • Title: Implantable Strands for Drug Delivery
  • Brief Description: The ’401 patent relates to a flexible, non-radioactive, implantable strand for delivering a therapeutic agent. The strand comprises a marker component for imaging, a biocompatible component, and a therapeutic agent, all of which may be disposed within a hollow interior.

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 brachytherapy device with a tubular housing, a therapeutic drug, and a radiopaque marker for imaging. However, Zamora’s device was radioactive. Petitioner asserted that Brem remedied this deficiency by teaching a non-radioactive implant for the localized delivery of a chemotherapeutic agent. The combination of Zamora's structure and Brem's non-radioactive approach allegedly rendered the claims of the ’401 patent obvious.
    • Motivation to Combine: A POSITA would combine Zamora and Brem because they address related technologies—implantable polymer devices for cancer treatment. Petitioner contended a POSITA would be motivated to remove the radioisotope from Zamora’s device, as taught by Brem, to provide greater flexibility in treatment protocols (e.g., allowing chemotherapy without concurrent radiation) and to avoid safety hazards associated with radioactive materials. A POSITA would also be motivated to add Zamora's radiopaque marker to Brem's device to facilitate placement and tracking, a known solution for a known problem.
    • Expectation of Success: Petitioner asserted a high expectation of success, as both references use similar polymers (e.g., PLA) and chemotherapeutic agents (e.g., paclitaxel) for the same purpose. Brem’s explicit teaching of an optional, rather than required, use of radiation therapy would have made the modification of Zamora’s device predictable.

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 built upon the combination of Zamora and Brem, with De Nijs added to provide further teachings on specific implant configurations. Petitioner argued that to the extent Zamora and Brem did not explicitly teach certain dimensional or structural limitations (e.g., specific lengths between 1 and 50 cm, or open-ended structures for drug release), De Nijs supplied these missing elements. De Nijs taught cylindrical, non-radioactive contraceptive implants with open ends, a length of 1-4 cm, and a diameter of approximately 2 mm.
    • Motivation to Combine: A POSITA would combine De Nijs with the Zamora/Brem combination because all three references are in the same field of biocompatible polymer implants for drug delivery. Both Zamora and Brem acknowledged contraceptive implants as relevant background art. Given the Patent Owner’s litigation position that the ’401 patent’s claims encompass contraceptive devices, De Nijs was presented as highly relevant art. The similar geometries and purpose would have motivated a POSITA to incorporate the specific design parameters from De Nijs.
    • Expectation of Success: Petitioner argued a POSITA would have an expectation of success in combining the teachings due to the overlapping technologies and the common goal of creating an implantable drug delivery device. Modifying the dimensions of the Zamora/Brem implant to align with those taught in De Nijs would have been a routine design choice.

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 asserted obviousness from the perspective of contraceptive implants. Petitioner argued De Nijs taught every element of the challenged claims except for the imageable marker component. De Nijs disclosed a non-radioactive, flexible, cylindrical implant for delivering contraceptive hormones. Petitioner contended that Schopflin filled the gap by teaching the addition of a radiopaque marker (barium sulfate) to a similar polymer-based, non-radioactive implant to allow for "improved X-ray localization."
    • Motivation to Combine: A POSITA would combine De Nijs and Schopflin because both are directed to the same application: implantable polymer devices for delivering contraceptive hormones. It was known in the art to use radiopaque markers to track implants for precise placement and subsequent removal. This was particularly relevant for the non-biodegradable implant of De Nijs, which would need to be located for removal. Adding Schopflin’s marker to De Nijs’s implant was therefore an obvious solution to a known problem.
    • Expectation of Success: Petitioner argued for a very high expectation of success due to the substantial overlap between the references. Both taught non-radioactive, cylindrical strands of similar dimensions (e.g., ~1.5 mm diameter, 1-4 cm length) containing similar therapeutic agents (hormones). The combination was presented as a simple and predictable substitution of known elements for their intended purpose.

4. Key Technical Contentions (Beyond Claim Construction)

  • Petitioner’s arguments relied on the assertion that the claims of the ’401 patent are not limited to brachytherapy. This contention was supported by referencing the Patent Owner's position in parallel district court litigation, which allegedly asserted that the claims were broad enough to encompass contraceptive implants. This framed the prior art related to contraceptive devices (De Nijs and Schopflin) as highly analogous and relevant.

5. Arguments Regarding Discretionary Denial

  • Petitioner argued that the asserted grounds were not redundant or cumulative to the art considered during prosecution. It was noted that while Zamora was addressed by the Examiner, Brem was not discussed in the prosecution of the ’401 patent. Furthermore, Schopflin was never cited, and De Nijs was one of over 600 references submitted in an IDS without being substantively addressed. This suggests the core combinations presented in the petition were not previously considered by the USPTO.

6. 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.