Nevro Corp v. Boston Scientific Corp

1. Case Identification

• Case #: IPR2017-01812
• Patent #: 6,895,280
• Filed: July 21, 2017
• Petitioner(s): Nevro Corp.
• Patent Owner(s): Boston Scientific Neuromodulation Corp.
• Challenged Claims: 22-24 and 26-30

2. Patent Overview

• Title: Spinal Cord Stimulation System
• Brief Description: The ’280 patent is directed to a spinal cord stimulation (SCS) system for treating chronic pain. The patent purports to improve on prior art by providing a "multi-channel" implantable pulse generator (IPG) with a replenishable power source, where the IPG features multiple, independently programmable stimulation channels that can provide concurrent, unique stimulation fields, as distinguished from prior art single-channel, multiplexed systems.

3. Grounds for Unpatentability

Ground 1: Obviousness of Claims 22-24 over Holsheimer, Munshi, and Wang

• Prior Art Relied Upon: Holsheimer (Patent 5,501,703), Munshi (Patent 5,411,537), and Wang (Patent 5,702,431).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Holsheimer disclosed the foundational multi-channel IPG capable of delivering simultaneous or alternating pulses from independent sources, meeting the core requirement of the ’280 patent. Munshi addressed the known problem of limited battery life in implants by teaching a "bioimplantable device" with a replenishable power source (rechargeable battery) and transcutaneous recharging. Wang further refined this by teaching alignment circuitry to ensure efficient energy transfer between the external charger and the implant, including monitoring reflected impedance to detect alignment. The combination of these references allegedly taught all elements of claims 22-24, including the multi-channel IPG, replenishable power source, external charger, and alignment monitoring.
  • Motivation to Combine: A person of ordinary skill in the art (POSA) would combine Holsheimer with Munshi to solve the well-known problem of finite battery life in implantable devices, thereby avoiding repeat surgeries for battery replacement. A POSA would have been further motivated to add Wang’s alignment circuitry to the Holsheimer/Munshi combination to address the consequential problem of ensuring efficient and reliable recharging, which was a known challenge for transcutaneous energy transfer systems.
  • Expectation of Success: The combination involved applying known solutions (rechargeable batteries, alignment circuits) to known problems (finite power, inefficient charging) in analogous implantable electrical stimulation systems. Therefore, a POSA would have had a high expectation of success.

Ground 2: Obviousness of Claim 26 over Holsheimer and Alo

• Prior Art Relied Upon: Holsheimer (Patent 5,501,703) and Alo (a 1998 journal article titled "Computer Assisted and Patient Interactive Programming of Dual Octrode Spinal Cord Stimulation...").
• Core Argument for this Ground:
  • Prior Art Mapping: Holsheimer disclosed the implantable multi-channel SCS system. Alo described what was argued to be the industry-standard method for implanting such systems: a trial period where leads are implanted and "externalized" through the skin to connect to an external trial stimulator. This allows the patient and physician to test stimulation parameters and confirm efficacy before committing to the surgical implantation of the permanent IPG. Petitioner asserted that claim 26 recites the precise steps of this conventional trial-to-permanent implantation procedure taught by Alo.
  • Motivation to Combine: A POSA implementing the Holsheimer IPG would have been motivated to employ the trial method from Alo for a clear, well-understood clinical benefit: confirming the therapy's effectiveness for a specific patient before performing the more invasive and costly permanent implantation. This was a standard practice to avoid unnecessary medical procedures and costs.
  • Expectation of Success: As Alo taught a standard implantation protocol for analogous SCS systems, a POSA would have had a high expectation of success in applying this method to the implantation of Holsheimer’s IPG.

Ground 3: Obviousness of Claims 27-30 over Barreras, Wang, and Engebretson

• Prior Art Relied Upon: Barreras (Patent 5,733,313), Wang (Patent 5,702,431), and Engebretson (Patent 5,024,224).

• Core Argument for this Ground:

  • Prior Art Mapping: This ground challenged method claims for charging the IPG. Barreras (’313 patent, not cited during prosecution) taught a rechargeable implantable medical device system where the implant telemeters a "stop" command to an external charger upon reaching full charge. Wang was cited for its teaching of using an alignment circuit to ensure efficient charging, as in Ground 1. For claims 28-29, Engebretson taught a method of communicating from an implant to an external device by switching the implant’s rectifier between full-wave and half-wave modes. This change in rectification creates a change in impedance, which can be detected by the external device to convey information, such as a "fully charged" status. For claim 30, Barreras disclosed an audible alarm in the external transmitter to alert the user.
  • Motivation to Combine: A POSA would combine Barreras and Wang to create an efficient recharging system. To improve the reliability of the "fully charged" signal, a POSA would replace Barreras' RF telemetry with Engebretson’s impedance-based communication method, which is less susceptible to electromagnetic interference. It would have been an obvious design choice to then use this reliable signal to trigger the audible alarm taught in Barreras to alert the user that charging is complete.
  • Expectation of Success: The combination used known communication and alert mechanisms from analogous implantable device systems to improve the functionality and reliability of a basic recharging system. A POSA would have expected the combination to work predictably.

• Additional Grounds: Petitioner asserted additional obviousness challenges, including claim 27 over Barreras and POSA knowledge alone, and claim 27 over Barreras in view of Wang. These grounds relied on the same core teachings from Barreras and Wang detailed above.

4. Key Claim Construction Positions

• "multi-channel implantable pulse generator (IPG)" (claims 22, 26): Petitioner argued this term must be construed as "an IPG that can simultaneously provide stimulation to two or more channels with different stimulation parameters." This construction was based on the ’280 patent’s explicit disavowal of prior art systems that used a single voltage source and multiplexing, characterizing them as not being true "multi-channel" systems.
• "sunning [sic] the change in rectification..." (claim 28): Petitioner argued "sunning" is a typographical error that should be read as "sensing." This term was construed as a means-plus-function limitation under §112. The claimed function is "sensing the change in rectification in the IPG," and the corresponding structure disclosed in the ’280 patent is a charge-complete detection circuit in the external charger that senses reflected impedance changes caused by the implant's rectifier switching from full-wave to half-wave.

5. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial under §325(d) would be inappropriate. While the Holsheimer reference was before the Examiner during prosecution, the petition presented it in new combinations with Munshi, Wang, and Alo, which were not previously considered. More significantly, Petitioner presented entirely new primary references, namely Barreras ’313 and Engebretson, which were not before the Examiner and allegedly teach the very features (e.g., stopping charge at a prescribed level, communicating via rectification change) that formed the basis for the patent's allowance.

6. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claims 22-24 and 26-30 of the ’280 patent as unpatentable.